Nanozymes: recent advances for sustainable agricultural development

Abstract

Agricultural production is currently facing numerous abiotic and biotic stresses. To mitigate the impacts of these stresses on crop yields, conventional agrochemicals have been widely employed to support farming practices. However, these chemicals exhibit limited functionality and are prone to overuse and residue accumulation on agricultural products, leading to environmental concerns such as pollution and bioaccumulation, which may hinder the development of sustainable agriculture. These drawbacks restrict their broader application in future sustainable agricultural systems. Notably, nanozymes possess unique advantages, including enhanced stability, tunable catalytic activity, and functional versatility. They exhibit significant potential in optimizing plant growth environments, mitigating stress conditions and enhancing crop stress resistance. As a promising alternative, nanozymes demonstrate the capability to address the limitations of conventional agrochemicals while advancing sustainable agricultural practices. Building on this progress, this review first explores the essential properties required for nanozyme applications in agriculture. It further categorizes nanozymes based on their diverse catalytic activities and discusses their roles in sustainable agricultural practices. Additionally, this review addresses current challenges in the field and proposes future directions for nanozyme-based agrochemicals. The goal is to deepen readers’ understanding of recent advances in agricultural nanozymes and stimulate broader scientific interest to explore their potential to advance sustainable agriculture. It is also hoped to provide some constructive inspirations for subsequent scientific research.

---

1. Introduction

Agricultural production is facing various abiotic and biotic stresses (such as pathogen infection, extreme temperatures, drought and heavy metal exposure). These stressors will affect the homeostasis of reactive oxygen species (ROS) in plant systems, leading to the overproduction of ROS in plants, including hydrogen peroxide (H₂O₂), hydroxyl radicals (˙OH) and superoxide radicals (O₂˙⁻). These ROS predominantly accumulate in plant cellular organelles, notably mitochondria and chloroplasts. Such ROS imbalance can critically impair the redox equilibrium, with severe cases manifesting as significant inhibition of plant growth and developmental processes, ultimately leading to substantial reductions in crop yield.^1–4 Conventional agrochemicals have been extensively employed to enhance agricultural productivity, yet their unsustainability poses significant challenges to the advancement of sustainable agricultural systems. These chemical inputs are prone to trigger cascading ecological disturbances, including overapplication scenarios, bioaccumulation phenomena, resistance development in target organisms, and persistent environmental contamination. Such multifaceted limitations have substantially constrained their broad-spectrum applicability within modern sustainable agricultural paradigms.^5–7

Nanotechnology and nanomaterials (NMs) currently represent the most promising approaches reported to address these issues, with nanotechnology playing a pivotal role in the development of sustainable agriculture and precision agriculture. In recent years, driven by continuous advancements in nanotechnology-enabled pesticide applications, a new generation of nano-pesticides has emerged. These innovative formulations exhibit enhanced characteristics including higher biocompatibility, environmental friendliness, superior stability, and stimuli-responsive targeting capabilities (intelligent responsiveness).^8–11 Nano-pesticides refer to organic or inorganic chemical agents prepared through nanotechnology for treating or preventing pests, bacteria, fungi, and plant diseases. They can be categorized into two primary classes:^12,13 the first class comprises pesticide delivery systems utilizing NMs as encapsulation vectors, including metal–organic frameworks (MOFs) as representative organic/inorganic hybrid materials. These systems focus on stimuli-responsive nano-carriers capable of achieving targeted release of active ingredients, which can encapsulate conventional pesticides for delivery to plant infection sites. Current advancements have led to various intelligent-responsive nano-carriers for sustained pesticide release.^14–16 While these smart nano-carriers have realized on-demand pesticide release with enhanced spatial and temporal resolution compared to traditional controlled-release systems, their core functional components remain conventional pesticides. Consequently, they cannot circumvent limitations of traditional pesticides, such as growth resistance from prolonged usage. Furthermore, environmental contamination caused by pesticide runoff persists as a critical challenge. The second category of nano-pesticides encompasses NMs possessing inherent pest-resistant and disease-suppressing functionalities, such as metal-based nanomaterials and carbon-based NMs. These materials exhibit therapeutic or defensive properties for plants, which can effectively mitigate the issues in the first category.^9,17 Notably, emerging nanozymes capable of mimicking natural enzymatic activities have garnered significant attention. Some of them have excellent properties such as small size, high biocompatibility and excellent stability, and have great potential in addressing the problems of agricultural production such as alleviating oxidative stress in plants and in promoting crop growth.^18–20

In response to the imperatives of sustainable agriculture, researchers have dedicated research efforts to developing agricultural nanozymes. In 2004, Manea et al. first designated gold NPs (Au NPs) with ribonuclease-like activity as “nanozymes”.^21,22 Subsequently, Yan and colleagues in 2007 first reported that Fe₃O₄ NPs exhibit peroxidase-like catalytic properties, marking the advent of a new era in nanozyme research.²³ Nanozymes are synthetic enzymes with enzyme-like nanocatalytic materials that can simulate the activity of natural enzymes. Compared with traditional natural enzymes, nanozymes have higher stability, persistence, tolerance and multi-enzymatic activity, so they are widely used in agriculture, environmental protection, biomedicine and other fields.^24–26 Nowadays, many relevant studies have reported that the enzyme-like activity of nanozymes can improve the growth environment of plants, help alleviate various biotic and abiotic stresses faced by crops, and further promote the growth of crops.^27–29 According to their different mimetic enzyme activities, nanozymes can be divided into two categories: (1) the oxidoreductase family, including peroxidase (POD), laccase (LAC), catalase (CAT), oxidases (OXD) and superoxide dismutase (SOD); (2) the hydrolase family, including esterase, urease, protease, and nuclease.^18,29

It is evident that there are relatively few review articles on the role of nanozymes in promoting sustainable agricultural development. Based on this, this work firstly discusses the characteristics of nanozymes when they are applied in agriculture; and then summarizes the classification of nanozymes based on their different catalytic activities, such as SOD-like, OXD-like, POD-like, CAT-like, LAC-like, and multi-enzymatic activities, etc.; while discussing their applications in sustainable agriculture. Finally, some problems existing in the current research are pointed out, and suggestions are made for the future development direction of nanozyme pesticides. The aim is to deepen the understanding of the latest achievements in agricultural nanozymes, so as to draw more and more researchers’ attention to explore the great potential of nanozymes in promoting sustainable agriculture. Meanwhile, it is hoped to provide some constructive inspiration for the subsequent scientific research.

2. Physicochemical properties of agricultural nanozymes

Nanozymes, as a class of nanoscale materials with enzyme-like activities, integrate some of the advantages of enzymes and NMs. They exhibit excellent stability in various external environments, as well as highly efficient and tunable catalytic activities. With the continuous development of synthesis technologies, researchers have gained a deeper understanding of the physicochemical properties of nanozymes, such as their morphology, size, and structure. They are also able to customize nanozymes according to specific requirements to meet diverse application needs. The physicochemical properties of nanozymes largely determine their application potential and possible impacts on agricultural ecosystems. Moreover, these properties may be directly related to their efficacy, stability, and impacts on the environment and humans. This inspires us that in order to better exploit their application value and contribute to the sustainable development of agriculture, it is necessary to conduct in-depth investigations into their basic physicochemical properties to prepare more efficient and controllable agricultural nanozymes. In the following, we will introduce the basic physicochemical properties of nanozymes from the aspects of their special structure, particle size and surface charge characteristics, stability, and biocompatibility.

2.1 Special structure

Creating a specific nanozyme structure helps to enhance its catalytic function. Nanozymes with different structural characteristics usually exhibit different efficacies.^30–32 For example, in metal-based nanozymes, the different surface valence states of the metal active centers play a major role in their catalytic behavior. They have a catalytic mechanism closer to that of natural enzymes, promoting electron transfer during the catalytic process.³³ The excellent catalytic performance of metal-based nanozymes can generally be improved through the following approaches: (1) structural modulation of metal active centers; (2) synergistic effects among multimetallic nanozymes; (3) interface engineering to form heterojunction structures; and (4) design of materials with specific surface morphologies and crystallographic facets. Among non-metal nanozymes, carbon-based nanozymes usually have good biocompatibility and multiple enzyme-like activities due to the unique electronic and geometric structures of the nanocarbon materials at their active centers.^34,35 In addition, nanozymes with a morphology featuring a higher surface area and abundant pores can display better catalytic performance.^36,37 The morphology of carbon-based nanozymes constitutes a critical factor influencing their performance, where nanostructures with higher surface areas and abundant porosity exhibit enhanced catalytic properties. Subsequent sections therefore systematically summarize the design strategies and characteristics of zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) carbon-based nanozymes.

Metal-based nanozymes prepared from metal materials possess unique metal active centers. Their distinctive electronic structures enhance the efficiency of electron transfer and catalytic substrate adsorption. Nanozymes with different metal active centers also exhibit differences in catalytic activity. A research study has integrated four noble-metal porphyrins (Ir, Ru, Pt, and Pd) into a Zr-based metal–organic framework (MxP).³⁸ Due to the strong interaction between Zr(IV) and carboxylate linkers, nanozymes with a robust structure were obtained. The porphyrins in the nanozymes are anchored at the porphyrin center through atomic metal–N coordination, which can mimic the active sites of natural peroxidases. Among them, MIrP shows higher POD-like activity (685.61 U mg⁻¹) than horseradish peroxidase (HRP). The excellent catalytic activity of MIrP stems from its strong H₂O₂ adsorption capacity and low energy threshold. Moreover, compared with traditional MFeP, its unique structural design endows it with better stability at room temperature and in high-concentration H₂O₂ environments.

In addition, multi-metal nanozymes are composite systems composed of multiple metal ions. The synergistic effect between multiple metals promotes the electron transfer or transport of the composite system, thus the system exhibits unique catalytic activity. A novel ultra-small high-entropy alloy NP (US-HEANP) has been reported in recent studies.³¹ This nanozyme, composed of five noble metals (Ir, Pt, Ru, Pd and Rh), was fabricated via a metal–ligand cross-linking strategy. The unique multi-metallic composition and ultra-small size endow it with exceptional nanozyme performance. Specifically, the high-entropy alloy structure exhibits distinct high-entropy effects and lattice distortion characteristics, which synergistically modulate the electronic structure and adsorption energy of the catalyst, thereby optimizing its catalytic activity. Experiments have shown that US-HEANP exhibit POD-like activity and can catalyze endogenous H₂O₂ to generate highly toxic ˙OH. The calculated Michaelis constant (K_m) values of US-HEANP for H₂O₂ and TMB are 4.094 mM and 34.40 μM, respectively, and the maximum reaction velocity (V_max) values are 1.882 × 10⁻⁷ M s⁻¹ and 2.457 × 10⁻⁷ M s⁻¹ respectively, indicating good catalytic activity. In addition, another research study adopted a reverse oxide/alloy structure. Co₇Fe₃ was used as the alloy core, which was encapsulated by ZnO and then stabilized with a carbon layer.³⁹ Finally, a nanozyme Co₇Fe₃/ZnO@C with multi-enzyme activity was designed. This structural design significantly enhances the enzyme-like activity of the nanozyme by optimizing the electronic structure and transmission path. By mimicking multiple natural enzymes (SOD, CAT, and POD) and directly scavenging ˙OH, it can regulate ROS balance to protect cells and tissues from oxidative damage.

Furthermore, through rational adjustment of metal components and optimizing the valence states of metal active sites, the catalytic performance of active centers can be further enhanced. Zhang et al. successfully developed a symbiotic nanozyme catalytic system with CAT-like and SOD-like enzymatic activities by controlling metal active sites through electron transfer and constraint anchoring, modulating vacancy concentrations, and enhancing electron transport.⁴⁰ The nanozyme exhibited increased Ce³⁺/Ce⁴⁺ and Mn³⁺/Mn²⁺ ratios of 0.229 and 2.043, respectively, which were higher than those of the control samples (Fig. 1(A)). In chemical environments, it demonstrated extremely high affinity for H₂O₂ (K_m = 7.194 mM) and a V_max value of 5.863 μM s⁻¹, significantly surpassing those of other Ce-based and Mn-based nanozymes (Fig. 1(B)). This demonstrates its superior CAT-like enzymatic activity. Furthermore, they validated the SOD-like activity of the nanozyme using the nitroblue tetrazolium chloride (NBT) colorimetric assay. As shown in the experimental data of Fig. 1(C), the system exhibited strong absorption at 580 nm after NBT addition, with the CeO_x/Mn₃O₄ treatment group displaying a significantly greater reduction in the 589 nm absorption peak compared to controls. Notably, a 20 μg mL⁻¹ nanozyme solution exhibited 82.88% O₂˙⁻ scavenging efficiency at room temperature. Additionally, Fig. 1(D) reveals that the SOD-like activity of CeO_x/Mn₃O₄ (19 176.05 U mg⁻¹) was significantly higher than that of other control groups. In this system, CeO_x (bacteria-shaped) nanoclusters are firmly anchored on the octahedral Mn₃O₄ (root-shaped) nanocarriers to form a biomimetic nanozyme system (CeO_x/Mn₃O₄) with multiple active sites (Fig. 1(E)). As shown in Fig. 1(F), the tightly coupled restricted anchoring facilitates electron transfer, and the increase in vacancies promotes electron transport. These two factors effectively improve the catalytic activity of the system, providing insights for the design of nanozymes with high catalytic activity.

Fig. 1 (A) The ratios of Ce³⁺/Ce⁴⁺, Mn³⁺/Mn²⁺, and O_sur/O_lat in Mn₃O₄, CeO₂ and CeO_x/Mn₃O₄ were obtained using XPS. (B) Catalytic kinetics of CeO_x/Mn₃O₄ CAT-like activity: Michaelis–Menten curves obtained by varying H₂O₂ concentrations (left); corresponding Lineweaver–Burk plot with H₂O₂ as the substrate (right). (C) SOD-like activity simulation of CeO_x/Mn₃O₄: UV absorption spectra of SOD-like activity in nanozyme catalytic systems measured by the NBT staining method (left); inhibition rate of O₂˙⁻ by different concentrations of CeO_x/Mn₃O₄ at room temperature (right). (D) CeO_x/Mn₃O₄ exhibited superior SOD-like activity compared with other control groups. (E) Corresponding schematic illustration of rhizobium-like CeO_x nanoclusters confined and anchored on root-like Mn₃O₄ octahedral nanocarriers, leading to lattice interweaving and electron transfer from Mn²⁺ to Ce⁴⁺. (F) Diagram of electron transfer between Mn and Ce atoms.⁴⁰ Copyright 2024, John Wiley and Sons.

A heterojunction is a structure formed by the interfacial bonding of two or more distinct materials (typically with different band gaps). Its unique structural configuration often endows materials with distinctive physical and chemical properties. The introduction of chemical bond coupling and band structure modulation at the material interface can significantly enhance the catalytic performance of nanozymes.^41–43 As shown in Fig. 2(A), a research study has obtained a Ni/CoMoO₄ heterostructure nanozyme through interface engineering by introducing a large number of Ni–O–Co bonds.⁴⁴ Compared with CoMoO₄, it exhibits a larger surface area and more abundant pores, which provide sufficient space for active sites and promote substrate adsorption. During the reaction process, electrons are transferred from Ni⁰ to Co³⁺, and Co³⁺ is converted into Co²⁺, which promotes the reaction kinetics and is beneficial to improving the catalytic activity. In this Ni/CoMoO₄ heterostructure with strong Ni–O–Co bonds, the strong electronic interaction (Ni–O–Co bonds) between Ni and CoMoO₄ promotes charge transfer and reduces the reaction energy barrier. Fig. 2(B) illustrates the catalytic mechanisms of the heterojunction nanozyme for OXD-like (left) and POD-like (right) enzymatic activities. Ni/CoMoO₄ with OXD-like activity promotes the generation of O₂˙⁻ and oxygen vacancies (OVs), thereby further oxidizing TMB. Briefly, the POD-like catalytic process of Ni/CoMoO₄ involves the following steps: (1) substrate adsorption: H₂O₂ binds to the active sites; (2) electron transfer: electrons from the Ni⁰–O–Co³⁺ bonds in Ni/CoMoO₄ are transferred to H₂O₂, accelerating the critical reaction step (1/2H₂O₂ → ˙OH); and (3) TMB adsorption: lone pair electrons from amino groups of TMB interact with Ni²⁺–O–Co²⁺, restoring Ni²⁺–O–Co²⁺ to the initial Ni⁰–O–Co³⁺ state. This facilitates electron transfer from Ni⁰–O–Co³⁺ to H₂O₂. It not only breaks the linear relationship between the active sites and reaction intermediates in traditional nanozymes but also significantly enhances the dual-enzyme-like activity.

Fig. 2 (A) Schematic diagram of Ni/CoMoO₄ synthesis through interfacial engineering. (B) Study on the enzyme-like catalytic mechanism of Ni/CoMoO₄: OXD-like enzyme (left) and POD-like enzyme (right).⁴⁴ Copyright 2022, ACS. (C) Investigation of antioxidant enzyme activity differences in Pd nanocrystals with distinct surface facets using ESR experiments: CAT-like activity (left, samples containing 10 mM H₂O₂, 0.1 mM 15N-PDT, with 25 μg mL⁻¹ Pd naonocubes/octahedrons and without (control) vs. 10 U mL⁻¹ CAT); SOD-like activity (right, O₂˙⁻ in the Xan/XOD generating system, without (control) and with 25 μg mL⁻¹ Pd nanocrystals vs. 1 U mL⁻¹ SOD).⁴⁵ Copyright 2016, ACS.

Besides, the regulation of the catalytic activity of nanozymes is also closely related to their surface morphology and exposed crystal planes. Chen et al. compared the enzyme-like activities of Pd nanocubes and Pd octahedrons and found a close relationship between the surface energy of Pd nanocrystals and their antioxidant enzyme-like activities.⁴⁵ Compared with Pd nanocubes with a higher-energy {100} facet, Pd octahedrons with a lower-energy {111} facet exhibit higher SOD-CAT-like antioxidant activity. They investigated the differences in antioxidant enzyme-like activities between two surface-faceted Pd nanocrystals using electron spin resonance (ESR) (Fig. 2(C)). Notably, the dissolved oxygen rate of Pd octahedrons increased more rapidly than that of Pd nanocubes, indicating that Pd octahedrons exhibits higher CAT-like activity compared to cubic Pd. Similarly, Pd octahedrons demonstrated superior scavenging activity toward O₂˙⁻ radicals relative to nanocubic Pd. Meanwhile, the results of theoretical computational simulations show that Pd cubes with {111} facets exhibit greater H₂O₂-scavenging activity and O₂˙⁻-scavenging activity, which is consistent with the experimental observations. This indicates the potential influence of the morphology (surface energy) of nanozymes on their activity.

Non-metallic nanozymes mainly refer to NMs based on carbon structures. Compared with certain metal-based nanozymes, carbon-based nanozymes eliminate the risk of metal ion leaching and exhibit superior environmental compatibility, thereby offering greater potential for sustainable agricultural development. At appropriate concentrations, these nanozymes can penetrate into plants and affect their metabolic processes. As a result, they have a positive impact on plant growth, showing great potential in crop treatment.^46,47 The shape of carbon-based nanozymes influences their relevant effects in plant therapy. A recent report compared the priming effects of tubular single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) on the phytopathogen Pseudomonas syringae pv tomato DC3000. Fig. 3(A) displays the experimental treatment process, where plant leaves were treated with different conditions: water, 1 mg L⁻¹ or 10 mg L⁻¹ SWNTs, or GO. Compared with GO, plants treated with SWNTs reduced the pathogen load by 56% when resisting the plant pathogen, showing a stronger immune response (Fig. 3(B)). Moreover, at a concentration of 10 mg L⁻¹, SWNTs exhibited greater potential in promoting plant growth. The plate counting assay in Fig. 3(C) further validated the results related to plant growth promotion. As shown in Fig. 3(D), EDF-HSI imaging is utilized for visualization, demonstrating that SWNTs were only detectable at a depth of 0.8 cm. The reason for this result is that the tubular structure of SWNTs enables them to be transported farther within the plant, triggering a more intense wound response. However, coating SWNTs with bovine serum albumin weakens this response.⁴⁸ The sharp edges and special morphologies of carbon NMs facilitate their penetration of cell membranes and cell walls. Moreover, carbon NMs have the potential to mimic relevant mechanical stresses. Therefore, the immune signals they induce are similar to the wound responses typically triggered by mechanical stimuli. This indicates that plants treated with carbon NMs may exhibit stronger resistance to certain plant pathogens.

Fig. 3 (A) Schematic diagram of 4–5-week-old plants subjected to different treatments and bacterial infection. (B) Transcriptional level analysis of oprF gene by qPCR at 24 hours post-infection. (C) Corresponding plate counting analysis. (D) Visualization of NM transportation in leaves using EDF-HSI imaging technology (red pixels represent NM distribution identified by hyperspectral features; blue pixels indicate the presence of NMs).⁴⁸ Copyright 2024, ACS.

Based on this, Table 1 presents the properties of carbon-based nanozymes with varied shapes and dimensionalities. 0 D carbon NMs (carbon quantum dots and fullerenes) have a relatively high specific surface area and high surface energy. They exhibit excellent substrate affinity and enzyme-like activity. The easily modifiable nano-fullerenes have a highly symmetric spherical structure and can act as electron acceptors, playing a role similar to SOD.^30,49 1D CNTs possess a large specific surface area, high strength, and excellent physical and chemical properties (good electronic tunability, high anti-aggregation ability, and electrical conductivity).^50,51 Li's team treated rice seedlings with low-concentration SWCNTs and multi-walled carbon nanotubes (MWCNTs). The results showed that the activities of SOD and POD enzymes in the rice seedlings increased, and the levels of O₂˙⁻ and H₂O₂ slightly increased. It promoted leaf growth and seedling development, accelerating the growth of rice seedlings.⁵² Compared to the SWCNT-treated group, seedlings subjected to MWCNT treatment exhibited a more pronounced increase in both O₂˙⁻ and H₂O₂ levels. Through multi-dimensional physiological impact studies, it has been demonstrated that under low-concentration CNT treatment, there may be a relationship between reactive oxygen species and plant hormones that promotes the growth of rice seedlings. 2D carbon materials such as graphene have relatively large lateral dimensions. Their unique geometric structures can provide more pores or defects, which is conducive to creating more active sites.⁵³ GO is one of the important derivatives of graphene. The carboxyl, hydroxyl, epoxy and carbonyl functional groups contained in it endow GO with high water-dispersibility. Therefore, GO has been widely used in many fields. Among them, the applications of GO in the field of crop stress resistance mainly include resistance to drought stress and saline–alkali stress.^54,55

Table 1 Classification of carbon-based nanozyme materials by dimensionality

Type	Material	Structure properties	Advantage	Enzyme-like activity	Ref.
0D	Carbon dots (CDs) and carbon quantum dots (CQDs)	Sp^2-bonded carbon structures	Superior enzyme-like activity and substrate affinity	SOD, CAT, POD, and OXD	30
		Rich in oxygen-containing functional groups	High charge transfer efficiency
		High surface energy and specific surface area	Facile surface functionalization
			Robust biocompatibility
	Fullerenes	Highly symmetric hollow cage-like structures	Superior photodynamic activity	SOD and POD	49
		Delocalized π-double bond structures	Superior enzyme-like activity and substrate affinity
		High surface energy and specific surface area	High charge transfer efficiency
1D	CNTs	Single-atom-thick 2D hexagonal carbon lattices	Good electronic tunability	POD and OXD	50 and 51
		Large lateral dimensions	High anti-aggregation capability and electrical conductivity
		Unique geometric structures providing more defects or voids	Superior anti-aggregation capability
		High surface area	Superior enzyme-like activity
			Robust biocompatibility
2D	Graphene	Single-atom-thick 2D hexagonal carbon lattice	Easily modifiable surface functional groups	SOD and POD	48 and 52
		Large lateral dimensions	Abundant catalytic sites
		Unique geometric structure enabling more defects/voids	Superior enzyme-like activity
		High surface area
	Transition-metal carbides/nitrides (MXenes)	Layered structure with regular geometric shapes	High electrical conductivity and hydrophilicity	POD, OXD, SOD, and CAT	53–55
		High surface area and abundant surface functional groups	Adjustable surface termination
			Controlled thickness with high mechanical strength

---

To meet the requirements of different application scenarios, contribute to the sustainable development of agriculture, enhance crop stress resistance and yield, it is crucial to design nanozymes with special structures.

2.2 Particle size and surface charge characteristics

The size effect of nano-pesticides refers to the significant changes in their physicochemical properties and application performance compared with traditional pesticides due to their particle sizes being within the nanoscale range. Through the size effect, the number of active sites on the surface of NMs per unit mass can be adjusted, thereby enhancing or reducing the catalytic activity of nanozymes.^56,57 The particle size of nanozymes plays a decisive role in their effective penetration and performance in plants.

Generally speaking, nanozymes with smaller sizes have a larger specific surface area, and the proportion of surface atoms is relatively high. This makes them more likely to interact with the surrounding medium or dispersant, thus achieving better dispersibility. Moreover, they have more active sites to bind with substrates, thereby enhancing the catalytic activity.^58,59 A study conducted by Yan's group concluded that 30 nm Fe₃O₄ NPs exhibit stronger POD-like activity than 150 nm and 300 nm Fe₃O₄ NPs.²³ This difference in activity is closely related to the size of the nanocrystals, which reflects the influence of the size effect on catalytic activity. In addition, a recent study on the foliar application of iron oxide nanozymes on soybean leaves further clarified the relationship between size and effects, providing insights for the precise design and application of nanozymes.⁶⁰ The experimental results showed that foliar application of γ-Fe₂O₃ nanozymes with different particle sizes had the significant impact on soybean growth, nitrogen-fixation ability, yield, and nutritional quality. This impact was clearly size-dependent. As shown in Fig. 4(A), treatment with 30 and 50 mg L⁻¹ S–Fe₂O₃ NMs resulted in 55.4% and 38.7% increases in fresh shoot biomass of soybean, respectively, which were 2.0-fold and 1.4-fold higher than those in the commercial iron fertilizer group (160 mg L⁻¹ EDTA–Fe). Notably, Fig. 4(B) reveals that foliar application of 30 mg L⁻¹ γ-Fe₂O₃ NMs enhanced shoot biomass in the order of S–Fe₂O₃ NMs > M-Fe₂O₃ NMs > L-Fe₂O₃ NMs, demonstrating a distinct size-dependent effect. In promoting soybean growth, enhancing yield, and improving seed quality, S–Fe₂O₃ NMs demonstrated greater advantages (Fig. 4(C)). After six applications of S–Fe₂O₃ NMs, the grain dry weight per soybean plant increased by 35.3%, which was significantly higher than that of the EDTA–Fe treatment group. Its effect was superior to that of the commercially available iron fertilizer (EDTA–Fe). It showed greater advantages in promoting soybean growth, increasing yield, and improving seed quality. This further reveals the crucial role of particle size in plant growth promotion.

Fig. 4 (A) Fresh biomass of soybean shoots and roots after foliar application of 160 mg L⁻¹ EDTA–Fe and varying concentrations (10, 30, 50, and 100 mg L⁻¹) of S–Fe₂O₃ NMs. (B) Fresh biomass of soybean shoots and roots after foliar application of 160 mg L⁻¹ EDTA–Fe and 30 mg L⁻¹ γ-Fe₂O₃ NMs with different sizes. (C) Yield of soybean plants after foliar application of 160 mg L⁻¹ EDTA–Fe and 30 mg L⁻¹ S–Fe₂O₃ NMs (3 or 6 applications).⁶⁰ Copyright 2022, ACS. (D) High spatiotemporal resolution imaging of NPs in plants and their interaction model with leaves.⁶² Copyright 2020, ACS. (E) Reconstructed nano-CT images of Arabidopsis root tips; hyperspectral mapping visualization of Au NPs in root tips; and schematic diagram of distribution and translocation of positively or negatively charged Au NPs in roots.⁶³ Copyright 2017, ACS.

However, nanozyme dimensions are not universally optimized by minimizing size. Excessively small NPs may induce excessive accumulation within plant cells, potentially disrupting normal cellular metabolic processes.^30,61 In plant applications, the pore sizes of cell walls and stoma may vary significantly across different plant species. Consequently, practical implementations require tailored design of nanozymes with species-specific dimensions and surface charge characteristics. A study demonstrated that the effective delivery of NPs to guard cells, extracellular spaces, and chloroplasts is dependent on their size, charge, and the specific plant species involved.⁶² They discovered that hydrophilic NPs with hydrodynamic diameters below 20 nm and 11 nm, respectively, and a positive surface charge (>15 mV), exhibited the highest foliar delivery efficiency into guard cells, extracellular spaces, and chloroplasts of cotton and maize. The enhanced affinity between positively charged NPs and the negatively charged plant cell walls, coupled with the negative transmembrane potential of cell membranes (Fig. 4(D)) likely explains their superior foliar delivery efficiency.

However, conflicting perspectives exist regarding the role of NP surface charge. One study demonstrated that negatively charged AuNPs (approximately 12 nm, −32 mV) were almost entirely distributed within the roots of Arabidopsis thaliana, predominantly localized in the intercellular spaces and near the cell walls. In contrast, positively charged AuNPs (approximately 2 nm, +46 mV) were largely entrapped as large aggregates in the outer mucilage layer of the root cap, and thus no internal root penetration was observed (Fig. 4(E)).⁶³ Another study investigated the transport efficiency and pathways of negatively and positively charged CDs in plants. The results demonstrated that negatively charged CDs displayed higher transport efficiency in cucumber and cotton roots compared to positively charged counterparts. And they were more effectively translocated from roots to leaves. This phenomenon might be attributed to the predominant transport of negatively charged CDs via symplastic and apoplastic pathways, whereas positively charged CDs primarily utilized the apoplastic route.⁶⁴ These divergent findings may arise from differences in plant species, growth stages, and variations in synthesized NMs.

In summary, researchers should prioritize comprehensive considerations of the size-dependent effects and surface charge characteristics of agronanozymes in agricultural applications. A critical objective is to establish an optimal size range that ensures not only efficient cellular internalization but also maintains high catalytic activity and biocompatibility.

2.3 Stability

Superior stability serves as the foundation for nanozymes to exhibit high catalytic efficiency, enabling them to function persistently within plant tissues or soil environments. This durability allows nanozymes to mediate critical biological processes, such as nutrient assimilation and metabolic regulation in plants. By optimizing their size, morphology, and surface modifications, highly stable nanozymes can minimize denaturation-induced deactivation while precisely tuning their catalytic properties to meet specific demands across diverse application scenarios.^65,66 The intrinsic properties of nanozymes significantly influence stability. Excessively small dimensions may induce stability degradation, as the heightened surface energy associated with nanoscale materials can lead to aggregation or oxidative damage, thereby compromising long-term structural integrity. Concurrently, environmental conditions (external factors), including pH, temperature, and ionic strength, exert varying degrees of influence on nanozyme stability. Robust environmental tolerance enables nanozymes to maintain high catalytic activity under dynamic conditions, resisting structural alterations, aggregation, or deactivation. This dual resilience ensures prolonged operational lifespan and enhanced stability in practical applications.^56,67 In addition, for some metal-based nanozymes, poor stability may lead to the leaching of heavy metal ions, which may in turn impact the environment. Therefore, to achieve better sustainability, surface modification methods such as physical barrier formation (anchoring a metal with a porous structure),⁶⁸ chemical anchoring,^69,70 core–shell structure formation,⁷¹ and ligand engineering⁷² can be considered to enhance the stability of metal-based nanozymes and reduce the risk of spillover of metal active centers. In a recent research study, a ZIF-8-pPt nanozyme was constructed, whose catalytic activity is 18 times that of traditional monodispersed Pt particles.⁷³ Experiments show that the ZIF-8-pPt nanozyme exhibits good stability. It maintains stable catalytic activity in the temperature range of 20–50 °C and has a wider pH tolerance range than natural HRP (Fig. 5(A)). Moreover, the structure of this nanozyme does not change significantly after multiple catalytic reactions, indicating excellent reusability and long-term stability. This stability primarily originates from the physical confinement effect, where the aggregation and migration of Pt nanoclusters are suppressed through the pore-channel encapsulation of ZIF-8, while the weak chemical anchoring within the framework also plays an auxiliary role in stabilizing the active sites. The Pt nanoclusters are uniformly distributed in the ZIF-8 framework and tightly bound to it. This structure enhances the catalytic activity and improves the overall stability of the nanozyme. As a MOF material, ZIF-8 possesses a highly ordered porous structure and excellent chemical stability. ZIF-8 provides a stable microenvironment for the Pt nanoclusters, effectively preventing their aggregation and deactivation through uniform distribution within the framework and strong interfacial interactions. Additionally, a study has demonstrated that structural optimization at the single-atom level can reduce stability limitations. They have demonstrated the design of a 3D biomimetic Pt–NC SAzyme by encapsulating platinum 2,4-pentanedionate within ZIF-8 molecular cages followed by pyrolysis.⁷⁴ In contrast to the physical confinement effect in ZIF-8-pPt, the Pt–NC SAzyme achieves atomic-level chemical anchoring through high-temperature pyrolysis-induced Pt–N₄ coordination bonds, thereby ensuring stable retention of single atoms under extreme conditions and during multiple cycles. DFT calculations revealed that the 3D porous structure of Pt–NC SAzyme enables a lower free energy barrier and shorter reaction pathway during the catalytic decomposition of H₂O₂. This 3D mass transport channels not only enhance catalytic activity but also reduce the risk of active site poisoning by minimizing intermediate residence time, thereby improving structural stability. As shown in Fig. 5(B), the Pt–NC SAzyme exhibited higher affinity for H₂O₂, with a significantly lower K_m value compared to those of Pt NPs and the NC group. Furthermore, the CAT-like specific activity (SA) further confirmed the superior catalytic activity of the Pt–NC SAzyme. In Fig. 5(C), the SA of the Pt–NC SAzyme (435.4 U mg⁻¹) was significantly higher than those of the Pt NP group (207.8 U mg⁻¹) and the NC group (34.1 U mg⁻¹). The low activity of nitrogen-doped carbon nanozymes (NC) underscores the necessity of single-atom sites. The aforementioned research demonstrates that 3D biomimetic structural optimization through a progressive design strategy transitioning from physical confinement of NPs to chemical bonding of single atoms significantly enhances the catalytic stability, providing a theoretical foundation for precise regulation of active sites and improvement of catalytic stability.

Fig. 5 (A) Temperature-dependent catalytic activity profiles of HRP and synthetic nanozymes.⁷³ Copyright 2024, John Wiley and Sons. (B) CAT-like activity investigation of Pt–NC SAzyme, NC, and Pt NPs (substrate: H₂O₂): Michaelis–Menten kinetic analysis (left) and Lineweaver–Burk plot (right). (C) Comparative analysis of specific activity (SA) among Pt–NC SAzyme, NC, and Pt NPs.⁷⁴ Copyright 2024, John Wiley and Sons.

2.4 Biocompatibility

As plants constitute integral components of ecosystems, the application of nanozyme-based pesticides may impose potential impacts on cohabiting organisms within the same ecological matrix, such as rhizosphere microbiota. Alterations in microbial diversity and metabolic activity could disrupt plant-microbe symbiosis, root-mediated nutrient cycling, and soil fertility, ultimately jeopardizing crop health and in severe cases, it may destabilize ecological equilibrium.^75,76 Therefore, high biocompatibility is one of the properties that must be possessed by nanozymes for agricultural use. It ensures that nanozymes can promote the healthy growth of plants with less negative effects. Li et al. investigated the impact of foliar application of Salvia miltiorrhiza-derived CDs on lettuce resilience under salt stress.⁷⁷ The related mechanism is illustrated in Fig. 6(A). CDs mimic SOD enzyme activity and exhibit excellent ROS-scavenging capacity. CDs catalyze the conversion of O₂˙⁻ to H₂O₂, and the generated H₂O₂ is subsequently transformed into ˙OH via Fenton reactions. CDs with potent ˙OH-scavenging capability reduce them to H₂O₂. Cytotoxicity assays confirmed the excellent biocompatibility of CDs (Fig. 6(C)). In vivo, CDs effectively translocated into plant cells and scavenged intracellular ROS (Fig. 6(B)), thereby alleviating salt stress in Italian lettuce. This resulted in a significant increase in both root and leaf biomass of salt-stressed lettuce plants (Fig. 6(D)).

Fig. 6 (A) Schematic illustration of the mechanism by which CDs alleviate oxidative damage in salt-stressed Italian lettuce. (B) Confocal imaging of ROS levels in mesophyll cells of Italian lettuce under different treatments: TES buffer (CK) and 2.0 mg mL⁻¹ CDs-180 infiltrated leaves, visualized by DCFH₂-DA staining. (C) Cytotoxicity evaluation of CDs-180 via CCK8 assay. (D) Effects of varying concentrations of CDs-180 on root dry weight (left) and leaf dry weight (right) in salt-stressed Italian lettuce seedlings.⁷⁷ Copyright 2021, ACS.

In parallel, some metal-based nanozymes have shown potential in biopharmaceutical and environmental applications due to their low biotoxicity, efficient bioaccumulation in tissues, and moderate biocompatibility.^78–80 Notably, Fe₃O₄ NPs were found to be predominantly absorbed by barley roots, significantly enhancing plant growth at elevated concentrations without phytotoxicity, thereby validating their biocompatibility.⁸¹ To engineer nanozymes with superior biosafety, priority should be given to plant-essential elements (e.g., Fe, Zn) or low-toxicity metals (e.g., TiO₂), while avoiding heavy metals during synthesis. Given the potential ecological risks posed by high-concentration nanozymes to plants and other organisms.⁸² Field trials should be conducted to establish safe and effective concentration thresholds.

3. Nanozymes capable of mimicking enzyme activity: classification

Nanozymes, used in sustainable agriculture, are mainly used to alleviate various stresses faced by crops by mimicking oxidoreductase activity. They can regulate the ROS balance of plants and increase their resistance. Nanozymes have significant catalytic activity and environmental tolerance and are considered as promising alternatives to natural enzymes. In this study, we comprehensively discuss various types of nanozymes for sustainable agriculture, including superoxide dismutase-like (SOD-like), oxidase-like (OXD-like), peroxidase-like (POD-like), catalase-like (CAT-like), laccase-like (LAC-like). The following research work on nanozymes with different mimetic enzyme activities is presented with the aim of providing a reference when selecting the appropriate nanozymes for different agricultural applications.

3.1 The oxidoreductase family

3.1.1 SOD-like nanozymes. The excessive accumulation of O₂˙⁻ induces oxidative stress and cellular damage. Superoxide dismutase, an antioxidant enzyme naturally present in biological systems, is ubiquitously distributed across microorganisms, plants, and animals. As a mitochondrial superoxide scavenging enzyme, SOD catalyzes the dismutation of O₂˙⁻ through a disproportionation reaction, with the specific mechanism formally described in eqn (1).

SOD-like nanozymes have natural SOD-like activities that can alleviate excessive accumulation of ROS (O₂˙⁻) through adsorption activation and electron transfer. They are important artificial enzymes that help plants to regulate the balance of ROS and improve stress tolerance.^83,84 Recently, various types of nanozymes with SOD-like activity have emerged. For example, Yu et al. developed a multiscale laminated nanozyme with a honeycomb-like morphology (MnO₂@GO) following the synthetic strategy outlined in Fig. 7(A).⁸⁵ The catalytically active δ-MnO₂ nanosheets were uniformly distributed on the GO surface. MnO₂@GO is characterized by a large specific surface area and abundant active sites. Its unique honeycomb-like multiscale laminated structure provides a confined space for the adsorption of O₂˙⁻ and catalytic reactions. Consequently, it is endowed with excellent SOD-like activity. As demonstrated by the WST-8 colorimetric assay in Fig. 7(B), the absorption peak at 450 nm (of WST-8 formazan) significantly decreased upon the addition of the nanozymes, corresponding to a SOD-specific activity of 161 U mg⁻¹ (Fig. 7(C)). Furthermore, MnO₂@GO exhibited a 95.5% specific inhibition rate against O₂^⋅- (Fig. 7(D)), which was 3-fold and 17-fold higher than those of the GO group and MnO₂ group, respectively. These results demonstrate the robust antioxidant performance of MnO₂@GO and propose a novel strategy for developing high-efficiency SOD nanozymes.

Fig. 7 (A) Synthesis strategy and honeycomb-like morphology schematic of MnO₂@GO nanozymes. (B) UV-Vis absorption spectra of SOD-like activity in MnO₂@GO nanozymes (0.5 mg mL⁻¹) measured by WTS-8 colorimetric assay. (C) Determination of SOD-like specific activity in MnO₂@GO. (D) Comparative analysis of SOD activity among MnO₂, GO, and MnO₂@GO.⁸⁵ Copyright 2023, Springer Nature. (E) Catalytic cycle Gibbs free energy profiles of hydroxyl-free (left) and hydroxyl-containing (right) CDs SOD nanozymes for SOD-like activity. (F) Quantitative analysis of SOD-like activity in CDs (prepared from activated charcoal, graphite powder, and carbon black) using the SOD assay kit (WST-1).⁸⁶ Copyright 2023, Springer Nature. (G) Determination of SOD-like activity in CDs by the WST-1 assay. (H) Comparative analysis of SOD-like activity between CDs-PS (passivated with carboxyl, hydroxyl, and amino groups) and CDs-PS-Hy (passivated with hydroxyl and amino groups).⁸⁷ Copyright 2023, John Wiley and Sons.

Recently, many CDs with enzyme-like activities have been reported by researchers. One study has also developed a carbon dot nanozyme with SOD activity (CDs SOD nanozyme).⁸⁶ By comparing the SOD-like enzymatic activities of CDs SOD nanozymes with and without hydroxyl groups, they validated the SOD-like catalytic mechanism of the CDs SOD nanozyme. Experimental results revealed that the activity of the CDs SOD nanozyme primarily depends on the binding of hydroxyl and carboxyl groups on its surface to superoxide anions, as well as electron transfer between carbonyl groups and π-systems. Computational analysis further demonstrated that the hydroxyl-containing CD nanozyme exhibited a significantly lower binding energy (−0.65 eV) with HO₂˙ radicals compared to the hydroxyl-free counterpart (−0.54 eV), indicating an enhanced ability of the hydroxylated CDs nanozyme to scavenge HO₂˙ radicals (Fig. 7(E)). Additionally, Fig. 7(F) shows that CDs derived from activated carbon displayed ultrahigh SOD-like activity (1.1 × 10 U mg⁻¹), providing a mechanistic foundation for their role in mitigating oxidative damage. In addition, another study used CDs as the matrix. By regulating the sp²/sp³ hybrid structure of the carbon core and surface functional groups, catalytic activity was improved.⁸⁷ This work complements the aforementioned study: both investigations confirm that the π-conjugated system serves as the central mediator for electron transfer. However, the former emphasizes the electrostatic interactions of hydroxyl/carboxyl groups, while the latter enhances the binding between CDs and O₂˙⁻ through the introduction of oxygen/nitrogen-containing functional groups. Optimizing the surface charge distribution of CDs promoted their electrostatic interaction with negatively charged O₂˙⁻. The experimental results showed that their SOD-like activity exceeded 4000 U mg⁻¹ (Fig. 7(G)). Furthermore, they demonstrated the influence of carboxyl and hydroxyl groups on the SOD-like activity of CDs through surface modification and passivation using 1,3-propanesulfonate (PS) and 4-sulfophenyl isothiocyanate sodium salt (SPI), respectively. As shown in Fig. 7(H), the SOD-like activity of CDs-PS (563 U mg⁻¹) was significantly lower than that of CDs-SPI (1147 U mg⁻¹). Notably, CDs-PS-Hy (883 U mg⁻¹) exhibited higher SOD-like activity than CDs-PS but still underperformed compared to CDs-SPI. These results confirm that carboxyl and hydroxyl groups enhance the SOD-like activity of CDs. These two studies collectively demonstrate that the synergistic interaction between hydroxyl and carboxyl groups constitutes a universal core mechanism underlying the SOD activity of CDs. The former investigation (PS/SPI experiments) primarily validated the essentiality of hydroxyl/carboxyl groups, while the latter (binding energy calculations) quantitatively elucidated the interaction strength between functional groups and free radicals, thereby providing multi-scale insights into mechanistic elucidation.

3.1.2 OXD-like nanozymes. Oxidases (OXD enzymes) are a class of enzymes capable of catalyzing the oxidation of substrates. They are extensively involved in various physiological processes in plants, particularly playing critical roles in metabolic regulation, stress resistance and defense mechanisms, and signal transduction. OXD-like nanozymes can catalyze substrate oxidation through surface active site interactions (e.g., metal centers and defect sites), electron transfer, and ROS generation.^56,88 For example, Gao et al. developed a high-performance OXD-like nanozyme based on Fe₃O₄@polydopamine-supported MnO₂ (IOPM) NPs.⁸⁹ The mechanism of its OXD-like activity is mainly based on the generation of single-linear state oxygen (¹O₂) by MnO₂ on its surface during the catalytic process (Fig. 8(A)). ¹O₂ is a highly ROS with a long lifetime and a strong oxidizing capacity that efficiently catalyzes the oxidation reaction of substrates (e.g., 3,3′,5,5′-tetramethylbenzidine, TMB) to produce blue oxidation products (oxTMB). UV-Vis absorption experiments revealed that the mixture of IOPM and TMB exhibited a strong absorption peak at 652 nm (Fig. 8(B)), demonstrating that IOPM possesses OXD-like activity capable of oxidizing TMB. Kinetic analysis further confirmed the superior OXD-mimetic performance of IOPM, with a calculated V_max of approximately 19.67 × 10⁻⁸ M s⁻¹ (Fig. 8(C)). In addition, Lin et al. prepared Co₃O₄ nanowires from M13 phage templates and found that they have excellent OXD-like activity and are able to mimic the catalytic mechanism of the natural OXD enzyme.⁹⁰ As shown in the EPR spectrum in Fig. 8(D), a strong signal at g = 2.003 (consistent with the characteristic signature of oxygen vacancies) was observed, indicating the presence of oxygen vacancies on the nanowire surface. The underlying mechanism is attributed to these surface-distributed oxygen vacancies. These oxygen vacancies can act as active sites to catalyze the TMB oxidation reaction. Unlike IOPM that relies on exogenous ¹O₂, Co₃O₄ nanowires directly capture electrons through endogenous oxygen vacancies, thereby circumventing the instability of ROS generation. This approach achieves a limit of detection (LOD) improvement from 0.1 U mL⁻¹ (IOPM) to 0.05 μM, highlighting the optimized catalytic mechanism and sensitivity breakthrough. Compared with the previous two studies employing ROS-dependent or oxygen vacancy-mediated OXD-like activity mechanisms, recent research has addressed oxygen dependency limitations through heterojunction interfacial electron transfer, demonstrating a V_max of 6.15 × 10⁻⁷ M s⁻¹. This research has developed a novel hybrid nanomaterial based on bovine serum albumin templates of gold nanoclusters (Au NCs) in conjunction with oxygen-deficient manganese dioxide (BAM), which exhibits a superior OXD-like activity.⁹¹ At the core of its catalytic mechanism lies in the strong interaction between Au NCs and MnO₂, which enables efficient substrate oxidation via electron transfer. Fig. 8(E) illustrates the catalytic mechanism. Initially, BAM, which exhibits high affinity for TMB, adsorbs TMB. Subsequently, TMB transfers an electron to the Au NCs. Following this, Mn⁴⁺ within the oxygen-deficient MnO_2−x nanosheets accepts an electron from the Au NCs, a process independent of ROS or dissolved oxygen. This unique catalytic pathway endows BAM with an ultrafast catalytic rate and exceptionally high catalytic efficiency. The aforementioned research protocols all rely on the redox activity of transition metal oxides (MnO₂ or Co₃O₄) and employ TMB as the substrate for colorimetric detection, demonstrating the shared objective in nanozyme development: emulating the high catalytic efficiency of natural OXD.

Fig. 8 (A) Schematic diagram of the catalytic mechanism of IOPM. (B) Validation of OXD-like activity in IOPM by UV-Vis spectroscopy with TMB as the substrate. (C) Steady-state kinetic analysis of IOPM.⁸⁹ Copyright 2024, Elsevier. (D) EPR spectra of nanowires.⁹⁰ Copyright 2024, Elsevier. (E) Schematic illustration of the catalytic mechanism of hybrid NMs.⁹¹ Copyright 2024, Elsevier.

3.1.3 POD-like nanozymes. Peroxidase (POD) is an oxidoreductase ubiquitously distributed in plants, animals, and microorganisms. In plant systems, POD is predominantly localized in the cell membrane and cell wall, exhibiting notably high enzymatic activity. This enzyme catalyzes the conversion of H₂O₂ into water while simultaneously oxidizing specific redox substrates (as illustrated in eqn (2), using TMB as a representative substrate).

POD-like nanozymes catalyze substrate oxidation through the decomposition of H₂O₂ to produce ROS, electron transfer, or cascade reactions with synergistic effects.^92–94 To date, an increasing number of nanozymes capable of mimicking both the catalytic activity and structural features of natural POD enzymes have been reported. For example, Li's group, through the precise geometric and electronic structure design.⁹⁵ A geometry similar to that of natural peroxidases was constructed through precise phosphorus (P) and nitrogen (N) coordination. As illustrated in Fig. 9(A), using ZIF-8 as the carbon and nitrogen precursor, the metal active centers were first anchored by precursor P while modulating the local coordination structure. Subsequently, a polymerization reaction was performed to coat the ZIF-8 surface with Fe ions and monomers of poly-(cyclotriphosphazene-co-4,4′-diaminodiphenylether) (PZM), forming a Fe/ZIF-8@PZM core–shell composite. Finally, pyrolysis of the composite yielded the FeN₃P-SAzyme. Experimental results demonstrated that FeN₃P-SAzyme exhibits significantly higher catalytic activity (316 U mg⁻¹), surpassing those of Fe₃O₄ nanozymes (9.12 U mg⁻¹) and P-free FeN₄-SAzyme (33.8 U mg⁻¹) by approximately 30-fold and 10-fold, respectively (Fig. 9(B)). Kinetic parameter studies (Fig. 9(C)) revealed that FeN₃P-SAzyme achieves a catalytic efficiency (K_cat/K_m = 1.40 × 10⁸ M⁻¹ min⁻¹) comparable to that of the natural HRP enzyme (K_cat/K_m = 1.15 × 10⁷ M⁻¹ min⁻¹). This indicates that the engineered structure successfully mimics both the catalytic activity and kinetic properties of natural POD by replicating the metal active sites of native enzymes. In contrast to the single-atom design of FeN₃P-SAzyme, another study has developed a biomimetic sulfur–iron–heme nanozyme (HCFe) with selective peroxidase POD-like activity.⁹⁶ Through a supramolecular self-assembly approach, they integrated heme and [Fe–S] structures by leveraging π–π stacking interactions between Fmoc-modified L-cysteine and heme (Fig. 9(D)). Comparative analysis of the nanozyme's POD-like and CAT-like activities under pH = 6.5 (tumor microenvironment) and pH = 7.4 (physiological pH) conditions revealed a pH-responsive activation state. Specifically, the HCFe nanozyme exhibited no CAT-like activity, while its POD-like activity remained inactive at pH = 7.4 but became enzymatically active at pH = 6.5 (Fig. 9(E) and (F)). These findings highlight the critical role of sulfur coordination in the active center in governing catalytic selectivity, which serves as a key factor enabling the mimicry of the native POD enzymatic mechanism. This design strategy shares with FeN₃P-SAzyme a common foundation in coordination environment engineering for nanozyme development, yet demonstrates complementary approaches: the former achieves targeted catalysis through sulfur coordination-mediated CAT activity suppression, while the latter directly enhances POD activity via phosphorus coordination. Both strategies fundamentally rely on coordination environment modulation as their core mechanism, but undergo optimization for distinct application scenarios.

Fig. 9 (A) Illustration of the preparation process of FeN₃P-SAzyme. (B) Comparative analysis of specific activity (U mg⁻¹) among Fe₃O₄, FeN₄-SAzyme and FeN₃P-SAzyme nanozymes. (C) Kinetic parameters of Fe-doped active sites in HRP enzyme, Fe₃O₄, FeN₄-SAzyme and FeN₃P-SAzyme nanozymes.⁹⁵ Copyright 2021, Springer Nature. (D) Schematic diagram of biomimetic sulfur–iron–heme nanozyme synthesis. (E) Investigation of POD-like activity: reaction time curves of the TMB colorimetric reaction catalyzed by HCFe nanozymes under varying pH conditions. (F) Study on CAT-like activity: dissolved O₂ production from H₂O₂ decomposition catalyzed by HCFe nanozymes at different pH values.⁹⁶ Copyright 2024, Springer Nature.

To further expand the dimensions of material design, Feng and colleagues developed a novel transition metal high-entropy nanozyme (HEzyme) by leveraging the structural entropy effect.⁹⁷ They utilized five transition metals, namely Mn, Fe, Co, Ni, and Cu, and broke through the component limitations of traditional single-metal or low-entropy alloys through multi-metal synergy. First, a uniform atomic distribution was achieved via the high-entropy effect. The diverse surface-active sites formed (such as metal–oxygen bonds and vacancies) could mimic the multi-active centers of natural enzymes. Then, the d-orbital coupling of different metals (e.g., the strong oxidizing property of Fe, the electron-transfer ability of Co, and the adsorption characteristics of Cu) was exploited to synergistically optimize the electron density and band structure, promoting HEzyme to decompose H₂O₂ into ˙OH radicals. Experiments showed that the K_cat/K_m value of HEzyme was close to that of natural HRP, indicating that its POD-like activity was comparable to that of HRP. Moreover, its catalytic efficiency and substrate affinity were significantly superior to those of traditional nanozymes. They achieved highly efficient POD-like activity through their unique surface atomic configuration and multisite orbital-coupling properties.

3.1.4 CAT-like nanozymes. Catalase (CAT) is a tetrameric heme-containing antioxidant enzyme ubiquitously present in plant chloroplasts, mitochondria, endoplasmic reticulum, and animal peroxisomes of liver and red blood cells. It catalyzes the decomposition of H₂O₂ (eqn (3)).⁹⁸ CAT plays a critical role in neutralizing H₂O₂ generated during plant cellular metabolic processes, thereby preventing its accumulation and subsequent oxidative damage to cells. Consequently, the level of CAT activity is closely associated with a plant's stress resistance.

CAT-like nanozymes can decompose H₂O₂ through adsorption-activated and redox reactions. Many NMs show CAT-like activity that catalyzes the conversion of H₂O₂ to H₂O and O₂.

For example, as illustrated in Fig. 10(A), a nanocomposite ZnO@PDA–Mn was synthesized by coating zinc oxide NPs (ZnO) with polydopamine (PDA) and manganese (Mn). The study monitored the O₂ generation capacity of 100 μg mL⁻¹ ZnO@PDA–Mn under varying H₂O₂ concentrations, generating a Michaelis–Menten curve (Fig. 10(B)). Subsequent Lineweaver–Burk fitting (Fig. 10(C)) determined the kinetic parameters of ZnO@PDA–Mn, with a K_m of 116.3 mM and a V_max of 6.03 mg (L min)⁻¹, demonstrating its exceptional CAT-like activity in decomposing H₂O₂ into H₂O and O₂.⁹⁹

Fig. 10 (A) Synthesis strategy of ZnO@PDA–Mn. (B) Steady-state kinetic analysis of CAT-like activity in ZnO@PDA–Mn with varying concentrations of H₂O₂. (C) Lineweaver–Burk plot of CAT-like activity in ZnO@PDA–Mn at 25 °C (substrate: H₂O₂).⁹⁹ Copyright 2024, RSC. (D) Synthesis strategy of Co–N₃PS SAzyme. (E) CAT-like specific activity (U μmol⁻¹ Co atom) of Co–N₃PS SAzyme.¹⁰⁰ Copyright 2023, John Wiley and Sons.

In addition, another study has synthesized an N, P, and S uniformly co-doped hollow carbon (NPS-HC) framework using poly (cyclotriphospazene-co-4,4′-sulfonyldiphenol) (PZS) and ZIF-8 as dual templates. Cobalt precursors were subsequently introduced to occupy the anchoring sites of the NPS-HC framework (denoted as Co²⁺/NPS-HC), successfully constructing a cobalt single-atom nanozyme with Co–N₃PS active centers (Fig. 10(D)).¹⁰⁰ By optimizing the coordination micro-environment of cobalt atoms (sulfur and phosphorus doping to regulate the electronic structure) and the reaction pathway (reducing the energy barrier for H₂O₂ decomposition) it precisely mimics the highly efficient catalytic mechanism of the natural CAT enzyme. Experimental results demonstrated that at pH = 10.8 (Fig. 10(E)), the Co–N₃PS SAzyme exhibited a CAT-like activity of 7046 U μmol⁻¹ Co atom, significantly surpassing the specific activity of native CAT (734.1 U μmol⁻¹ Co atom). This highlights the Co–N₃PS SAzyme's exceptional enzyme-mimicking performance, characterized by ultrahigh catalytic efficiency (approaching kinetic parameters of natural enzymes), substrate specificity (selective decomposition of H₂O₂ to H₂O and O₂), and structural stability (anchoring single-quantitative relationship between the active center configuration and performance has been revealed, providing a new “atom-level biomimetic” paradigm for the design of highly efficient artificial enzymes. Both aforementioned studies have overcome the limitations of conventional materials through biomimetic design (ZnO@PDA–Mn mimicking the Mn active site of CAT, and Co–N₃PS simulating the cobalt porphyrin structure of CAT): the former elucidated the quantitative correlation between the Co–N₃PS configuration and catalytic activity at the atomic scale. The latter achieved functional integration of antibacterial and antioxidant properties via a core–shell structure. Collectively, they validate that “modulating the microenvironment of active centers” constitutes the central strategy for enhancing nanozyme performance.

3.1.5 LAC-like nanozymes. Laccase (LAC) is a polyphenol oxidase with copper ions in its active center, and plays a crucial role in redox reactions. During the catalytic process, the four copper ions in the active center can be classified into three types: type 1 Cu (T1Cu), which is responsible for substrate oxidation, is located on the enzyme surface and directly binds to phenolic substrates; type 2 Cu (T2Cu) forms a triangular cluster structure with two type 3 Cu (T3Cu) ions and participates in the reduction of oxygen. LAC catalyzes the oxidation of phenolic substrates through the synergistic action of multiple copper ions while reducing oxygen to water. Firstly, substrate molecules bind to the copper ions in the active center of laccase. Subsequently, the electrons of the substrate are transferred to the copper ions through a specific pathway, resulting in the oxidation of the substrate and the reduction of the copper ions (the specific mechanism is shown in Fig. 11).^101,102 It plays a pivotal role in plants by sustaining multiple physiological processes, including lignin biosynthesis, stress resistance defense, wound healing (through phenolic cross-linking to form physical barriers), and regulation of secondary metabolism. These mechanisms collectively exert crucial functions in plant development, stress responses, and ecological interactions.

Fig. 11 Mechanistic flowchart of laccase-catalyzed oxidation of phenolic substrates.

The mechanism by which the nanozymes mimic the activity of LAC is largely dependent on their unique catalytic center and electron transfer mechanism. LAC-like nanozymes usually promote electron transfer by mimicking the active center structure of natural LAC and using surface metal ions as the active site to coordinate with the substrate molecules (the electron transfer mechanism includes: substrate binding, electron transfer and oxygen reduction). This mimics the catalytic process of oxygen reduction to water by natural LAC through a single electron transfer mechanism.¹⁰³ Wang et al. designed a novel species of biomimetic LAC-like nanozymes (CH–Cu). CH–Cu nanozymes were synthesized by liganding a cysteine–histidine dipeptide with copper ions (Fig. 12(A)).¹⁰⁴ This design demonstrates high structural similarity to the T1 copper active center of natural LAC, while effectively addressing the environmental sensitivity of native LAC through implementation of a rigid coordination architecture. Experimental results revealed that at varying substrate concentrations, the CH–Cu nanozyme exhibited Michaelis–Menten kinetic parameters of K_m and V_max = 0.42 mM and 7.32  ×  10⁻³ mM min⁻¹. This demonstrates not only substrate affinity comparable to natural LAC (K_m = 0.41 mM), but also superior catalytic efficiency (V_max = 6.41  ×  10⁻³ mM min⁻¹). This performance advantage originates from the dipeptide ligands’ optimization of electron transfer pathways at the copper active centers. In addition, the CH–Cu nanozymes showed remarkable stability under the conditions of extreme pH, high temperature, long-term storage, and high-salt environments, and their performance was superior to that of natural LAC. For instance, under aqueous storage conditions at 25 °C, LAC exhibited a gradual decline in catalytic activity and became completely deactivated by Day 9 (Fig. 12(B)). In contrast, the CH–Cu nanozymes retained 72% of their catalytic activity throughout the 20-day storage period. The developed CH–Cu nanozymes integrate high catalytic activity with exceptional stability, demonstrating significant potential to address the environmental tolerance limitations and recovery challenges inherent in natural LAC systems. In another study, two multivalent cerium-based metal–organic framework (Ce-MOF) materials (Ce-UiO-66 and Ce-MOF-808) have been designed to mimic the catalytic function of LAC.¹⁰⁵ These materials mimic the electron transfer mechanism of natural LAC by replacing traditional copper clusters with multivalent cerium (Ce³⁺/Ce⁴⁺) active centers, thereby broadening the metal selection scope for LAC mimicry. They selected 2,4-DP as a model substrate, demonstrating that the porous structure and high specific surface area of Ce-MOFs provide abundant active sites for substrate adsorption and catalytic reactions, thereby effectively enhancing their catalytic performance. Experimental results revealed that in the presence of LAC or Ce-MOFs, 2,4-DP was oxidized into quinone intermediates, which subsequently reacted with 4-AP to generate colored products detectable at UV510 nm (Fig. 12(C)). After 45 minutes of reaction, Ce-UiO-66 and Ce-MOF-808 produced significantly higher amounts of colored products compared to native LAC at equivalent mass concentrations, demonstrating their exceptional LAC-mimicking activity. In addition, Li's research team further integrated catalysis and separation technologies to design the GA–Cu nanozyme, utilizing Cu²⁺ as active centers with 2-aminoimidazole and glutathione (GSH) as ligands (Fig. 12(D)).¹⁰⁶ Compared to the dipeptide coordination in CH–Cu, the –SH group of GSH dynamically regulates the Cu²⁺/Cu⁺ redox states, while the electron bridge constructed by imidazole groups reduces the K_m value to 0.18 mM, demonstrating the effect of precise modulation of ligands on catalytic performance. Catalytic kinetics studies revealed (Fig. 12(E)) that GA–Cu exhibits a V_max of 7.53 × 10⁻³ mM min⁻¹, with its singlet oxygen (¹O₂)-dominated catalytic mechanism (validated by ESR) contrasting with the substrate direct oxidation pathways of CH–Cu and Ce-MOFs.

Fig. 12 (A) Schematic diagram of the synthesis process and biomimetic structure of CH–Cu nanozymes. (B) Stability comparison between LAC and CH–Cu at identical mass concentrations and varying storage durations.¹⁰⁴ Copyright 2019, Elsevier. (C) UV spectra of the supernatant from the chromogenic reaction mixture and the corresponding photographs of the mixtures.¹⁰⁵ Copyright 2022, Elsevier. (D) Schematic illustration of the biomimetic design and synthesis of GA–Cu nanozymes. (E) Michaelis–Menten curve (left) and the corresponding Lineweaver–Burk double-reciprocal plot (right) for 2,4-DP catalysis by GA–Cu nanozymes.¹⁰⁶ Copyright 2024, Elsevier.

3.2 The hydrolase family

Hydrolases are a class of biocatalysts that mediate hydrolytic reactions. This category encompasses lipases catalyzing ester bond cleavage, proteases facilitating amide/peptide bond scission, glycoside hydrolases (GHs) mediating glycosidic bond hydrolysis, among others.^107–109 Hydrolases play pivotal roles throughout important developmental stages of plants. During the seed germination phase, they degrade starch into glucose within seeds to provide energy reserves for sprouting, while simultaneously mobilizing storage proteins to support seedling establishment. In vegetative and reproductive growth phases, these enzymes assist plants in mitigating biotic and abiotic stresses, such as pathogen invasion and xenobiotic toxins, by degrading pathogen cell wall components (e.g., chitinases) and eliciting plant immune responses.^110–113 The general catalytic mechanism of natural hydrolases in hydrolytic reactions (exemplified by proteases) involves three sequential stages: (1) substrate binding, where catalytic residues specifically recognize and bind amino acid residues of the substrate via complementary electrostatic and hydrogen-bonding interactions; (2) nucleophilic attack on the carbonyl carbon of the peptide bond by the active-site nucleophile (e.g., serine hydroxyl or cysteine thiol), accompanied by concerted acid–base catalysis to mediate proton transfer and charge redistribution, culminating in peptide bond scission and water molecule release; and (3) product dissociation, wherein the enzyme releases hydrolyzed products from its active site, regenerating catalytic competency for subsequent substrate turnover.¹¹⁴

Inspired by the catalytic mechanisms of natural hydrolases, researchers have developed diverse nanozymes with hydrolase-mimicking activities.^115–117 These nanozymes are primarily engineered through two strategies: biomimetic design and emulation of natural enzymatic catalytic pathways.^118,119 For instance, Yu and colleagues uncovered the pan-glycoside hydrolase-like (p-GHs-like) activity of copper compound NPs (Cu₃P and Cu₂O NPs), which exhibit bond cleavage precision, anomeric carbon configuration selectivity, and catalytic attack modes analogous to natural GHs.¹²⁰ As illustrated in Fig. 13(A), these systems structurally replicate the two critical catalytic residues responsible for hydrolysis in natural GHs. Building upon the catalytic mechanisms of natural enzymes, they proposed two theoretically feasible pathways (path I and path II) for the NP-catalyzed hydrolysis of the artificial substrate PNPG (p-nitrophenyl-β-D-glucopyranoside). In both pathways, oxygen atoms of the NPs act as nucleophilic agents to attack the anomeric carbon of the glycosidic bond, while surface-adsorbed protons or copper atoms exhibit binding affinity toward the glycosidic oxygen. DFT calculations elucidated the reaction trajectories (Fig. 13(B)), revealing path I as the thermodynamically favored pathway. However, path II is an exothermic process that is thermodynamically unfavorable for the reaction progression. This mechanistic parallelism strongly supports the existence of catalytic sites on the NPs’ surface mirroring those of natural enzymes. Furthermore, building upon this biomimetic catalytic rationale, another study achieved a breakthrough by designing a molecularly imprinted polymer nanozyme (NP-Zn-6b) through biomimicking the active center structure of natural carbonic anhydrase.¹²¹ This bioinspired design primarily involves two structural strategies: (1) incorporation of Zn²⁺ as catalytic centers, and (2) construction of substrate-selective rigid cavities via molecular imprinting and post-modification, which precisely position coordinating groups (e.g., histidine-like moieties) around Zn²⁺ to replicate the enzymatic microenvironment. The Zn²⁺ ions synergize with proximal basic residues to activate H₂O, generating nucleophilic hydroxide ions for ester bond hydrolysis – a mechanism analogous to that of carbonic anhydrase. They demonstrated that the bioinspired nanozyme efficiently hydrolyzes unactivated alkyl esters under mild conditions (40 °C, neutral pH = 7). Experimental results revealed that NP-Zn-6b exhibits significantly higher activity in the hydrolysis of para-nitrophenyl hexanoate (PNPH) compared to monofunctional catalysts lacking Zn or basic groups. Notably, NP-Zn-6b displayed a distinct activity maximum at pH = 7 (Fig. 13(C)). Intriguingly, NP-Zn-6b also hydrolyzes a range of esters beyond PNPH in pH 7 buffer (Fig. 13(D)). The reactivity hierarchy suggests that the synthetic NP-Zn-6b esterase readily discriminates substrates based on positional shifts or additions of methyl groups, modulated by structural variations influencing substrate binding. This work transcends the conventional paradigm of traditional chemical catalysis reliant on strong acids/bases, pioneering the construction of an artificial enzyme system that integrates metal–base synergistic catalysis with substrate-selective recognition.

Fig. 13 (A) Two possible attack pathways (path I and path II) for PNPG hydrolysis catalyzed by Cu₂O and CuO NPs. (B) Energy profile diagrams of β-conformation (top) and α-conformation (bottom) glucose generated by Cu₂O and CuO NPs via path I and path II, respectively.¹²⁰ Copyright 2023, Elsevier. (C) pH-Dependent reaction rate curves of PNPH hydrolysis catalyzed by NP-Zn-6b compared with other catalysts. (D) Yield of 8–18 ester hydrolysis catalyzed by NP-Zn-6b in 25 mM HEPES buffer (pH = 7.0) at 40 °C after 4 hours.¹²¹ Copyright 2022, Elsevier.

3.3 Multienzymatic activity

With the rapid development of nanozyme technology and the increasing demand for catalysis, single-functional nanozymes have exhibited certain limitations. Multienzymatic nanozymes, due to their potential synergistic or cascade effects, often demonstrate superior catalytic efficiency compared to single-enzyme-like nanozymes.^122,123 In addition, plants in agricultural production often suffer from various stress conditions such as drought, high-temperature, low-temperature, pests and diseases. Nanozymes with multienzymatic activities can mimic the functions of multiple natural enzymes and enhance the stress resistance of plants through synergistic effects. Therefore, there is an urgent need to develop new NMs with multifunctional catalytic properties. A study developed ultrasmall calcium hexacyanoferrate(III) nanozymes (CaHF NPs) with quadruple enzyme-mimetic activities.¹²⁴ Experimental studies demonstrated that the SOD-like activity of CaHF NPs is concentration-dependent, achieving a 99% suppression rate of O₂˙⁻ at a concentration of 320 μg mL⁻¹ (Fig. 14(A)). Subsequent detection of NADPH depletion (via an absorption peak at 340 nm) revealed a sharp decline in NADPH absorbance, thereby confirming the GPx-like activity of CaHF NPs. Additionally, the TMB chromogenic reaction revealed that the maximum absorbance of ox-TMB at 652 nm decreased with increasing concentrations of CaHF NPs, reflecting their POD-like enzymatic activity. The CAT-like activity of CaHF NPs was determined by monitoring O₂ generation via a dissolved oxygen meter during the catalytic decomposition of H₂O₂, where a significant increase in O₂ production was observed within the first minute after adding CaHF NPs. The CaHF NPs with the aforementioned quadruple enzyme-mimetic activities exhibit broad-spectrum scavenging of multiple reactive oxygen and nitrogen species (RONS), including H₂O₂, O₂, O₂˙⁻, ˙OH, ONOO⁻ and NO, through a synergistic antioxidant mechanism, thus demonstrating potential in disrupting the vicious cycle of oxidative stress. Another study designed an ultrasound-enhanced nanozyme named ACPCAH.¹²⁵ This material is co-loaded with phosphorus-doped graphitic carbon nitride nanosheets, ultra-small gold NPs, and Cu_1.6O NPs, and is wrapped with L-arginine and hyaluronic acid (Fig. 14(B)). Similar to CaHF NPs, ACPCAH achieves multi-enzymatic activities (SOD, CAT, GO_x, POD, and NOS) by mimicking the active centers of natural enzymes. However, its innovation lies in the introduction of an ultrasound-responsive mechanism: dynamically enhancing catalytic efficiency through piezoelectric and sonothermal effects, which addresses the issue of limited activity in traditional nanozymes within complex wound microenvironments. Experimental results demonstrated that under ultrasound assistance, the catalytic activity was significantly enhanced, leading to effective scavenging of ROS. Fig. 14(C) and (D) evaluate the ultrasound-augmented POD-like and GO_x-like activities using the TMB chromogenic assay. A pronounced 40% increase in absorbance (indicative of POD-like activity) was observed for ACPCAH under sonication. The V_max values for H₂O₂ and TMB under ultrasound treatment reached 8.27 × 10⁻⁸ M s⁻¹ and 10.5 × 10⁻⁸ M s⁻¹, respectively, representing 25% and 69% enhancements compared to non-sonicated reactions. Additionally, the ultrasound-treated system exhibited a 16% improvement in the glucose consumption rate (V_max = 6.77 × 10⁻⁸ M s⁻¹) for its GO_x-like activity relative to the control group.

Fig. 14 (A) Study on enzyme-mimetic activities of CaHF NPs (from left to right: SOD-like, GPx-like, POD-like, and CAT-like activities).¹²⁴ Copyright 2023, Elsevier. (B) Schematic illustration of the design and synthesis strategy for ultrasound-augmented ACPCAH nanozymes. (C) POD-like activities of different treatment groups under conditions with or without ultrasound treatment. (D) GO_x-like activities of different treatment groups under conditions with or without ultrasound treatment.¹²⁵ Copyright 2023, ACS.

4. Nanozymes: applications in phytotherapy

Under physiological conditions, the generation and scavenging of ROS in plants constitute a dynamic equilibrium process (ROS homeostasis).¹²⁶ Low-level ROS play beneficial roles as signaling molecules in growth, development, and defense responses—for instance, activating stomatal closure mechanisms in guard cells to combat environmental drought and biotic stresses.^127,128 However, under stress conditions, the redox equilibrium in plants may be disrupted. Excessively accumulated ROS (O₂˙⁻, H₂O₂, and ˙OH) exhibit potent oxidative capacity, leading to membrane lipid peroxidation, protein denaturation, DNA damage, and other cellular component impairments, which can severely inhibit plant growth.¹²⁹ The development of materials capable of modulating ROS homeostasis in plant systems is therefore imperative. Extensive studies have demonstrated that certain high-performance nanozymes can internalize into plant cells and enhance the expression of antioxidant enzymes (e.g., SOD, CAT) and non-enzymatic antioxidants (e.g., glutathione, ascorbate). Application of nanozymes under stress conditions achieves dual synergies: by not only augmenting intrinsic ROS-scavenging capacity but also enzymatically modulating ROS levels to enhance stress tolerance, thereby mitigating stress-induced physiological damage and yield losses.^130,131 This approach can significantly reduce the application of synthetic chemical pesticides and fertilizers, decreasing their pollution to soil, water bodies, and the atmosphere. Accordingly, Table 2 catalogs diverse agricultural nanozyme materials, detailing their chemical compositions, enzymes-like activities, target organisms, and mitigation mechanisms against biotic stresses (e.g., pathogens/pests) and abiotic stresses (e.g., extreme weather, soil contamination).

Table 2 Nanozyme materials for promoting sustainable agriculture: applications in mitigating biotic and abiotic stresses

Type	Application	Nanozyme	Enzymes-like activity	Strategies for mitigating stresses	Application target	Ref.
Biotic stresses	Plant antiviral agent	Cu1.96S NPs	Protease	1. Chirality-dependent selective recognition for the QANPTTA epitope	Tobacco mosaic virus	138
				2. Photo-triggered site-specific proteolysis
				3. Virion structural disruption
	Pesticide	MON@CeO2	SOD	1. SOD-like activity for ROS scavenging	Nilaparvata lugens, Sogatella furcifera	139
				2. Downregulation of ROS-dependent P450 gene expression
				3. Reduction of detoxification enzyme activities
				4. Overcoming pesticide resistance
Abiotic stresses	Drought stress	Ag NPs	Catalyze ROS generation	1. ROS signal-triggered defense priming	Maize seed	148
				2. Root hair morphological remodeling
				3. Transcriptional reprogramming of defense pathways
		Fe-based NPs	POD	1. Environmentally friendly ROS homeostasis
				2. Enhancement of osmotic adjustment capacity
				3. Augmentation of antioxidant enzyme activities
		Yttrium doping-stabilized γ-Fe2O3 NPs	CAT and POD	1. Nanozyme-mediated ROS scavenging	Brassica napus	149
				2. Suppression of lipid peroxidation
				3. Enhanced growth and photosynthetic capacity
	Salinty stress	Ag NPs	POD	1. Nanozyme-catalyzed ROS generation (specifically ˙OH)	Rice seeds (Oryza sativa L.)	153
				2. Metabolic reprogramming accelerates biosynthesis and energy supply
				3. Activation of defense response genes and stress signaling molecules
		CDzymes	SOD and CAT	1. Scavenging ROS/RNS and free radicals	Pisum sativum Linn, Eucommia	154
				2. Regulating antioxidant enzymes
				3. Protecting key biomolecules
		Mn3O4	SOD and CAT	1. Boosting endogenous antioxidant metabolites	Cucumber (Cucumis sativus)	155
				2. Reducing oxidative damage and lipid peroxidation
				3. Accumulating osmoprotectants
				4. Modulating stress-responsive metabolic pathways
		V4AlC3 nanosheets	SOD, CAT and POD	1. Activation of antioxidant system
				2. Phytohormone signaling modulation	Pea seed	156
				3. Enhancement of energy metabolism
				4. Phytohormone signaling modulation
		CeO2 NMs	Antioxidative enzyme	1. Nanozyme-mediated ROS scavenging	Maize (Zea may L.)	157
				2. Maintenance of Na^+/K^+ homeostasis
				3. Enhancement of photosynthetic efficiency
				4. Down-regulation of lignin synthesis genes to accelerate cell elongation
	Heavy metal stress	CaHCF NPs	SOD, CAT, POD, GPX, TPX and APX	1. Multi-enzyme activities for direct ROS scavenging	Arabidopsis, Tomato	27
				2. Ion exchange to reduce Cd^2+ uptake and release Ca^2+
				3. Activation of endogenous antioxidants and gene regulation
				4. Restoration of photosynthesis and growth promotion
Other stresses	Cold stress (10 °C)	Yellow light CDs (YCDs) nanozyme	CAT	1. Selective photosynthetic activation mechanism	Kale-type overwintering (oilseed rape)	164
				2. Multi-enzyme activities for direct ROS scavenging
				3. Antioxidant Enzyme system enhancement mechanism
				4. Root proliferation promotion mechanism (synergistic effect)
	IMI stress	CDs	SOD and POD	1. Cascade nanozyme activities scavenging ROS	Italian lettuce (Lactuca sativa)	167
				2. Detoxification gene regulation for pesticide degradation
				3. Hormonal signaling pathway activation
				4. Nutritional quality and element homeostasis improvement
	Arsenic stress	Fe-CDs	SOD, CAT and POD	1. Multi-enzyme activities for direct ROS scavenging	Italian lettuce	168
				2. Suppression of arsenic uptake and enhancement of plant stress resistance
				3. Targeted regulation of ROS homeostasis

---

4.1 Responding to biotic stress

Various biotic stresses faced by plants, such as pathogenic bacterial infections and pest infestations, are important factors affecting crop production. Although conventional pesticides (for instance, insecticides and antimicrobials) can mitigate these biological infestations to increase crop yields. However, it also poses potential hazards to the environment and living organisms. Excessive application of xenobiotic agrochemicals compromises critical phyto-developmental processes through multilevel perturbations in physiological homeostasis and biochemical cascades, ultimately jeopardizing the sustainability paradigm in agricultural systems.^132–134 Nanozymes can augment the plant immune system by triggering the activation of defense-related genes and proteins, thereby bolstering the plant's resistance against pathogenic infections and pest infestations. This mechanism ultimately leads to a reduced reliance on conventional pesticides, effectively mitigating environmental contamination and ecological disruption caused by pesticide usage.^135–137

Bacteria, fungi, and insects are the primary pathogens responsible for plant diseases. Certain nanozymes can enhance plant antiviral resistance by scavenging ROS generated during pathogen infection, maintaining ROS homeostasis, and activating the plant's intrinsic defense mechanisms, thereby reducing viral damage. Others function as plant antiviral agents by directly inhibiting viral activity through protease-like catalytic activity. A study developed a novel plant antiviral agent (chiral 3 nm Cu_1.96S NPs) composed of copper sulfide NPs (3 ± 0.5 nm in diameter) and D-penicillamine as surface ligands (Fig. 15(A)).¹³⁸ This antiviral agent exhibits protease-like enzymatic activity, enabling specific recognition and binding to the Gln99-Ala105 fragment within the capsid protein of Tobacco Mosaic Virus (TMV). The nanozyme demonstrates high binding affinity (via a supramolecular bonding network) to the Gln99–Ala105 region of the viral capsid, while showing 3000–10 000-fold lower affinity to capsid proteins of other viruses. In addition, under green light irradiation, the antiviral agent hydrolyzes the amide bond between Asn101 and Pro102 in a polarization-dependent manner. As demonstrated in Fig. 15(B), the inhibitory efficacy against viral infection reached 98.7% in protoplasts and 92.6% in whole plants at 7 days post-treatment. The amount of viral nucleic acid is significantly reduced without triggering an allergic reaction in plants. Subsequently, the copper distribution in the treated plants was analyzed, and it was found that the copper content did not increase significantly, indicating that the antiviral agent has no significant impact on the environment. Circularly polarized light can significantly enhance the catalytic efficiency of chiral nanozymes. This photocatalytic-driven proteolytic cleavage provides an important reference for the development of novel photo-activated antiviral agents against plant viruses.

Fig. 15 (A) Design and synthesis strategy of chiral 3 nm Cu_1.96S NPs. (B) Contents of protoplast and plant viral nucleic acid extracts under different treatments.¹³⁸ Copyright 2022, Springer Nature. (C) SOD-like activity of MON@CeO₂ evaluated using a SOD detection kit. (D) Relative ROS intensity in N. lugens (JXF and NR) fed with rice seedlings treated with MON@CeO₂ (100 mg L⁻¹) for 24 h. (E) Effect of MON@CeO₂ on the expression levels of detoxification enzyme cytochrome P450 genes in N. lugens (JXF). (F) Effect of MON@CeO₂ on the expression levels of detoxification enzyme cytochrome P450 genes in N. lugens (NR) (JXF: field strains; NR: nitenpyram-resistant strains).¹³⁹ Copyright 2022, Elsevier.

In addition, another study developed a SOD-like nano-pesticide through redox-driven modulation of catalytic activity. Zeng et al. fabricated a nano-hybrid material, MON@CeO₂, by embedding CeO₂ within mesoporous organosilica NPs (MONs).¹³⁹ MONs served as templates with excellent biocompatibility and monodispersity, effectively preventing aggregation of CeO₂ NPs. This strategy shares conceptual similarities with the steric hindrance effect induced by D-penicillamine ligands in Cu_1.96S NPs, as both approaches employ interface engineering to optimize the exposure of catalytic sites. Experimental results demonstrated that MON@CeO₂ scavenged ROS in pests by mimicking SOD activity (Fig. 15(C)). The system effectively scavenges ROS within pest organisms (Fig. 15(D)). In contrast to the molecular recognition mechanism of Cu_1.96S NPs targeting viral capsids, MON@CeO₂ achieves broad-spectrum synergistic effects through systemic modulation of the ROS-P450 signaling pathway. This mechanism effectively suppresses ROS-dependent cytochrome P450 gene expression in both nitenpyram-resistant N. lugens (NR) and field-collected N. lugens (JXF) (Fig. 15(E) and (F)). As P450 genes play a pivotal role in pesticide metabolism in pests, their downregulation reduced detoxification enzyme levels, consequently increasing pest susceptibility to insecticides. This mechanism holds significant implications for prolonging insecticide efficacy, optimizing dosage regimes, and enhancing pest control sustainability.

4.2 Mitigation of abiotic stresses

Abiotic stresses faced by plants, in the form of drought, high temperature, high salinity, cold, nutrient deficiencies, heavy metals, etc., are the main cause of reduced crop yields globally. Plants subjected to abiotic stress undergo changes at the morphological, physicochemical, and molecular levels, and their growth and developmental conditions and productivity are adversely affected to some extent.^3,4 Excessive use of conventional pesticides also produces abiotic stress in plants. Pesticide stress affects plant health and ecosystem sustainability through mechanisms such as inducing the production of ROS in plants.^140,141 It is worth noting that nanozymes, which are potential alternatives to conventional pesticides, are able to help plants to maintain cellular stability and normal metabolic functions in abiotic stress environments, such as drought, salinity, and heavy metals. For example, nanozymes can increase the activity of antioxidant enzymes in plant cells and scavenge excess ROS generated by environmental stresses.²⁷ It can ensure plant growth and development in harsh environments, reducing crop yield reduction due to natural disasters, and enhancing plant resilience to abiotic stresses.

4.2.1 Drought stress. In recent years, drought caused by water scarcity has become a major obstacle to plant flourishing. Drought stress disrupts the water balance of crop systems, prompting the accumulation of osmoregulatory substances to maintain cellular water balance, while triggering the massive accumulation of ROS and activating antioxidant defense systems. This ultimately leads to crop growth inhibition, which causes problems of reduced yield and quality.^1,142 At this stage, many studies have been conducted to show the potential of nanozymes to cope with drought stress in agriculture, which is important for food security in water-scarce regions. Nanozymes can alleviate the accumulation of ROS generated by drought stress, maintain the normal structure and function of cells, and improve the water utilization efficiency of crops, thereby enhancing their antioxidant capacity and tolerance to drought stress.^143–145 Fe plays a crucial role in the physiological processes of plants. It can promote the synthesis of chlorophyll in plants and enhance their photosynthesis. Due to its super-magnetic and environmentally friendly properties, various types of nano-FeO_x have been developed to assist plants in withstanding adverse stress.^146,147 Chen and colleagues demonstrated that Ag NPs and Fe-based NPs enhance maize tolerance to multiple abiotic stresses, including drought, via ROS-mediated pathways.¹⁴⁸ Experimental data revealed that Ag NPs alleviated drought-induced seed germination inhibition by ROS generation. Ag NPs significantly improved germination rates and seedling vigor under drought stress: from 75.5% to 94.7% at 10% PEG, and from 50.2% to 75.2% at 20% PEG (Fig. 16(A)). Fig. 16(B) demonstrates that maize seedling vigor significantly increased under 10% PEG and 20% PEG conditions, rising from 424 to 628 cm% and 104 to 208 cm%, respectively. Environmentally benign Fe₂O₃ and Fe₃O₄ NPs similarly mitigated drought impacts through ROS modulation. Under 14.9% PEG-induced drought, (Fig. 16(C) and (D)) Fe₂O₃ NPs enhanced seedling vigor, shoot length, and root length by 13.9%, 33.7%, and 10.2%, respectively. The aforementioned results demonstrate that Ag NPs and Fe-based NPs, as seed priming agents, significantly enhance maize seed/seedling tolerance to diverse abiotic stresses (drought, salinity, low temperature, and combined stresses). They provide a cost-effective, eco-friendly, and efficient technical solution to mitigate agricultural threats from climate change-induced extreme weather events.

Fig. 16 (A) Effect of AgNP seed priming on the maize germination rate under drought stress. (B) Impact of AgNP seed priming on maize seedling vigor under drought stress. (C) Influence of Fe₂O₃ and Fe₃O₄ NP seed priming on the maize seedling vigor index under different abiotic stresses. (D) Effects of Fe₂O₃ and Fe₃O₄ NP seed priming on shoot and root length of maize seedlings under different abiotic stresses.¹⁴⁸ Copyright 2023, ACS. (E) Phenotypic images of plants rehydrated after 5-day drought stress (from left to right: control group irrigated with nutrient solution; nutrient solution with 0.8 mg mL⁻¹ ION; nutrient solution with 2 mg mL⁻¹ ION). (F) The H₂O₂ and fresh weight (G) of plants irrigated with nutrient solution containing or lacking ION after 5-day drought stress.¹⁴⁹ Copyright 2017, Springer Nature.

Building on this foundation, researchers have developed Yttrium doping-stabilized γ-Fe₂O₃ NPs (IONs) to meet the persistent stress resistance requirements of crops during their growth phase. This material functionally integrates the catalytic properties of iron-based nanomaterials and stability optimization strategies from prior studies, ensuring sustained efficacy throughout plant developmental stages.¹⁴⁹ These Y-doped γ-Fe₂O₃ NPs exhibit dual CAT-like and POD-like activities for efficient ROS scavenging. Different irrigation treatments were applied to drought-stressed plants, and phenotypic imaging revealed that ION treatment alleviated drought stress impacts on the plants (Fig. 16(E)). Experimental data (Fig. 16(F)) confirm that NP irrigation under drought stress significantly reduces leaf H₂O₂ accumulation (by 38.2%) and MDA production (by 27.5%), while markedly increasing fresh biomass (21.3%) (Fig. 16(G)), leaf length (18.7%), and chlorophyll SPAD values (34.6%). These collectively enhance the drought resilience and rehydration recovery of Brassica napus. This dual-functional strategy synergizes nanozyme-mediated ROS regulation with iron nutrient supplementation, simultaneously boosting crop stress tolerance and reducing reliance on conventional fertilizers, thereby mitigating environmental contamination risks.

4.2.2 Salinity stress. More and more soils are facing salt stress with the constant impact of climate change, reduced precipitation, and human activities such as irrigation and fertilization. Salt stress inhibits plant growth, yield and product quality, and to ensure efficient agricultural production and food supply, improving plant salt tolerance has received widespread attention.^29,150–152 According to research reports, AgNPs can enhance plant defense capabilities against various abiotic stresses, such as salinity stress. Yan et al. investigated the pretreatment effects of AgNPs on rice seeds,¹⁵³ revealing that AgNPs can mimic POD activity by generating ROS to trigger metabolic and transcriptional reprogramming in seeds. This mechanism significantly improved rice's salt tolerance and blast resistance. AgNPs activate plant defense signaling through controlled ROS generation. Building on this mechanism, subsequent studies have expanded the dimensions of ROS regulation-transitioning from signal induction to direct scavenging or multilayered synergistic mechanisms. Gong et al. synthesized CDzymes via microwave-assisted rapid thermal polymerization using glucose (carbon source) and histidine (nitrogen source).¹⁵⁴ CDzymes exhibit broad-spectrum antioxidant capabilities through synergistic mechanisms, including electron transfer, hydrogen atom donation, and enzyme-like catalysis (SOD-/CAT-like activity). The CDzymes ultimately demonstrated efficient scavenging of ROS (˙OH, O₂˙⁻, H₂O₂), RNS (˙NO, ONOO⁻), and stable free radicals. In saline stress trials, CDzymes significantly mitigated oxidative damage in Pisum sativum Linn and Eucommia under salt-alkali stress while enhancing plant growth via osmoregulatory balance modulation and endogenous enzyme activation. With exceptional biocompatibility, CDzymes offer a novel nanozyme-based strategy for agricultural stress resilience and demonstrate potential for broader environmental stress remediation applications. Furthermore, Lu et al. investigated the application of Mn₃O₄ nanozymes in cucumber growth and stress resistance.¹⁵⁵ Experimental results demonstrated that this nanozyme exhibits superior antioxidant enzyme-mimicking activity, effectively scavenging ROS. The Mn₃O₄ nanozyme catalyzes H₂O₂ decomposition through valence state cycling among surface Mn²⁺, Mn³⁺, and Mn⁴⁺, demonstrating robust CAT-like enzymatic activity. This mechanism alleviates oxidative stress, thereby promoting cucumber plant growth under adverse conditions. As shown in Fig. 17(A), the application of Mn₃O₄ nanozymes alleviated salt stress effects in cucumber plants. Compared to salt-stressed plants without treatment, Mn₃O₄ nanozyme application significantly increased biomass by 17.7% (Fig. 17(B)). These results indicate that Mn₃O₄ nanozymes successfully mitigated salt-induced stress in cucumbers and maintained biomass stability. In addition, Liu et al. developed a novel nano-enhancer for saline–alkali soil crop cultivation.¹⁵⁶ They synthesized ultrathin V₄AlC₃ nanosheets (Fig. 17(C)) by etching V₄AlC₃ precursors to remove Al layers, followed by ultrasonic exfoliation. XPS analysis revealed surface-enriched –OH functional groups and mixed-valence vanadium species (V³⁺/V⁴⁺/V⁵⁺), endowing the nanosheets with multienzymatic activities (SOD-, CAT-, and POD-like). Experimental results demonstrated that under 200 mM NaCl-induced salt stress, V₄AlC₃ treatment significantly reduced ROS fluorescence intensity in pea seed cells compared to the salt-stressed control group (Fig. 17(D)). Under 200 mM NaCl stress, 0.25 μg mL⁻¹ V₄AlC₃ treatment enhanced pea seed germination by 2.2-fold (recovering to 89% of the control) and increased root length by 3.5-fold (Fig. 17(E) and (F)). The nanosheets functioned via triple synergistic mechanisms: (1) direct ROS scavenging, significantly reducing oxidative damage marker MDA; (2) upregulating SOD/CAT/POD gene expression; and (3) modulating hormone signaling and ion transporter activity.

Fig. 17 (A) Phenotypic images of cucumber plants under different treatments (blank control, NaCl, NaCl + Mn₃O₄ nanozymes). In the NaCl + Mn₃O₄ nanozyme group, foliar application of Mn₃O₄ nanozymes was initiated at the three-week-old stage and continued daily for one week. (B) Fresh biomass of cucumber tissues under different treatments.¹⁵⁴ Copyright 2020, RSC. (C) Phenotypic photographs of pea seeds after 9 days of different treatments (blank control, NaCl, NaCl + V₄AlC₃ nanosheets). (D) ROS fluorescence intensity in pea seeds under different treatments detected by DCFH-DA. (E) Application of V₄AlC₃ nanosheets significantly promoted the recovery of germination rate and radicle length in pea seeds subjected to salt stress (200 mM NaCl treatment) (F).¹⁵⁶ Copyright 2024, ACS. (G)–(J) Growth parameters (fresh biomass (G), dry biomass (H), and STI (I)) and phenotypic images (J) of maize under salt stress after foliar application of CeO₂ NMs at different concentrations (1, 5, 10, 20, and 50 mg L⁻¹). (K) Images of maize ears and corn kernels (L) after foliar application of 10 mg L⁻¹ CeO₂ NMs to salt-stressed maize plants.¹⁵⁷ Copyright 2022, Elsevier.

CeO₂ NPs, as rare earth nanomaterials with exceptional catalytic properties, can mimic natural SOD enzymatic activity. In plants, they serve as an efficient ROS scavenger, exerting SOD-like effects while enhancing salt tolerance.¹⁵² Their SOD-like activity primarily stems from the redox cycling between Ce³⁺ and Ce⁴⁺, which facilitates oxygen release and electron transfer to form oxygen vacancies or defects. These oxygen vacancies enable the storage and release of oxygen, providing additional active sites that promote electron transfer and reactant adsorption, thereby amplifying catalytic efficiency under stress conditions.¹⁵⁷ The research team led by Wang reported the mechanism by which CeO₂ NMs alleviate salinity stress in maize.¹⁵⁸ Phenotypic and biomass experimental results (Fig. 17(G), (H) and (J)) revealed that foliar application of 10, 20, and 50 mg L⁻¹ CeO₂ NMs significantly alleviated salt stress-induced growth inhibition in maize after one week of treatment. Concurrently, the salt tolerance index (STI) was markedly enhanced by 69.5%, 69.1%, and 86.8%, respectively (Fig. 17(I)). Furthermore, as shown in Fig. 17(K) and (L), salt stress adversely affected the development and maturation of maize ears and corn kernels, while 10 mg L⁻¹ CeO₂ NMs significantly mitigated these adverse effects. Transcriptomic analysis revealed that CeO₂ NMs scavenged ROS through their intrinsic antioxidant enzymatic properties. Post-application, antioxidant defense system-related genes were restored to normal control levels. Additionally, while optimizing Na⁺/K⁺ homeostasis, CeO₂ NMs increased carbon sources in root exudates to enhance rhizobacterial richness and diversity, elevating the abundance of halotolerant plant growth-promoting rhizobacteria (HT-PGPR). Compared to traditional fertilizers, CeO₂ NMs demonstrate both high efficiency and cost-effectiveness.

4.2.3 Heavy metal stress. Nowadays, heavy metals (such as cadmium, lead, mercury, etc.) have posed a serious threat to plant growth. They can disrupt physiological processes such as photosynthesis and respiration, affecting the normal growth and development of plants. In addition, heavy metals interfere with the redox balance of plants and induce excessive accumulation of ROS, which can lead to oxidative damage.^159,160 Nanozymes can significantly enhance phytoremediation and reduce the uptake of heavy metals by enhancing the tolerance of plants to heavy metals and removing the excessive ROS induced by heavy metals. They are conducive to the sustainable use of soil resources and provide a new and effective strategy for alleviating heavy metal stress.^27,161 Recently, researchers have successfully developed several NMs that integrate multiple properties. Shen et al. developed calcium hexacyanoferrate NPs (CaHCF NPs) by using an environmentally friendly and direct method, which is a multifunctional nanozyme targeting ROS.²⁷ Experiments showed that the average size of CaHCF NPs is approximately 5 nm, and the average hydrodynamic diameter is 10 nm, enabling them to be effectively absorbed by plants. After being absorbed by the roots, CaHCF NPs can mimic six types of enzyme activities to relieve ROS stress in plants. The multienzymatic activities of CaHCF NPs are validated in Fig. 18(A)–(G). SOD-like activity was assessed via NBT reduction assay (Fig. 18(A)), where the generation of NBT formazan was significantly suppressed with increasing CaHCF NP concentrations, confirming their SOD-like capability. Subsequently, dissolved oxygen measurements revealed that CaHCF NPs catalyzed H₂O₂ decomposition into O₂ (Fig. 18(B)), with O₂ bubble production proportional to the H₂O₂ concentration (Fig. 18(C)), demonstrating intrinsic CAT-like enzymatic activity. POD-like activity was verified through a TMB chromogenic reaction, showing a characteristic absorption peak at 652 nm for CaHCF NP-treated groups. Kinetic analysis of POD-like activity (Fig. 18(E) ad (F)) yielded K_m and V_max values of 4.7103 mM and 3.53 × 10⁻³ mM s⁻¹, respectively, based on the Michaelis–Menten equation, indicating efficient H₂O₂ scavenging analogous to natural POD. Additionally, CaHCF NPs exhibited GPX-, TPX-, and APX-like activities, with spectroscopic evidence confirming their efficacy in scavenging ˙OH, further substantiating their role in ROS elimination. Moreover, through cation exchange with Cd²⁺, Cd can be immobilized by the cyano groups, reducing the plant's absorption of Cd and decreasing the risk of Cd accumulation in the food chain. It is worth noting that the cadmium-based Prussian blue analog (Cd-CaHCF NPs) formed after ion exchange still possesses good multienzymatic activity and direct ROS scavenging ability, which can synergistically enhance the plant's antioxidant system. They utilized 120 μg mL⁻¹ CaHCF NPs to alleviate the inhibitory effects of H₂O₂ and CdCl₂ on the model plant Arabidopsis and the commercial crop Solanum lycopersicum (tomato). Fig. 18(G) and (I) illustrate the validation of cadmium stress mitigation efficacy through foliar spray and soil irrigation of CaHCF NPs in tomato plants. Experimental results showed that CdCl₂ treatment induced reduced leaf number, diminished leaf area, chlorosis, stunted plant height, and impaired root development in tomato seedlings. These inhibitory effects were significantly mitigated by CaHCF NPs treatment, with both foliar and soil application demonstrating substantial remediation. This indicates the significant potential of CaHCF NPs in alleviating abiotic stress in crops. This work offers a promising strategy for constructing a bio-antioxidant system with multienzymatic activities to mitigate diverse plant stresses.

Fig. 18 (A) NBT assay for SOD-like activity of CaHCF NPs. (B) Photograph of the reaction between H₂O₂ and CaHCF NPs with CAT-like activity. (C) Amount of O₂ generated by CaHCF NPs reacting with H₂O₂ at different concentrations (0, 1, 3, and 5 M). (D) POD-like activity of CaHCF NPs. (E) Absorbance–time curves of CaHCF NPs in H₂O₂ solutions at varying concentrations (10, 20, 30, 40, and 50 mM). (F) Michaelis–Menten kinetics (left) and the Lineweaver–Burk plot (right) for the POD-like activity of CaHCF NPs. (G) GPx-like activity, TPX-like activity (substrate: DTNB), and APX-like activity of CaHCF NPs (from left to right). (H) ESR spectra of CaHCF NPs (˙OH radical elimination using DMPO as a trapping agent). (I) Phenotypic photographs of Cd-stressed tomato seedlings alleviated by foliar application of CaHCF NPs (1-month-old seedlings treated with Cd stress and CaHCF NPs applied every two days for 18 days). (J) Phenotypic photographs of Cd-stressed tomato seedlings alleviated by soil irrigation with CaHCF NPs (15-day-old seedlings treated with Cd stress and CaHCF NPs via soil irrigation for 30 days).²⁷ Copyright 2024, John Wiley and Sons.

4.2.4 Other stresses. In addition to drought, salinity, and heavy metal stress, extreme temperatures (e.g., hyperthermia or chilling) can also induce excessive accumulation of ROS in plant systems. Furthermore, low-temperature stress adversely affects crop overwintering, causing cellular tissue damage, reduced enzymatic activity, and impaired nutrient absorption and metabolism, thereby disrupting normal growth and development.¹⁶² Beyond mitigating ROS overaccumulation, it is crucial to protect and enhance root proliferation and the expression of stress resistance-related genes in crops. These mechanisms synergistically reduce the impacts of low-temperature stress on cold-sensitive plants.¹⁶³ For example, a study proposed a kind of yellow-emitting CD nanozyme (YCDs).¹⁶⁴ Experiments showed that through seed treatment, the root proliferation of the kale-type overwintering rapeseed (oilseed rape) under low-temperature stress (10 °C) was significantly enhanced (Fig. 19(A)). Under low-temperature stress, YCDs can emit relatively stable yellow light (around 580 nm). This light of a specific wavelength can be recognized by phytochromes or photoreceptors in plant cells, promoting the photosynthesis-related processes of plants. As a result, it stimulates the up-regulation of genes related to root growth and root elongation. With its CAT-like activity, YCDs can effectively scavenge the excessively accumulated ROS, leading to a significant decrease in the H₂O₂ and MDA concentration in the roots and stems of rapeseed. It can enhance the ability to inhibit ˙OH, thus effectively alleviating the low-temperature-induced oxidative damage. Fig. 19(B)–(E) demonstrate that YCD nanozymes significantly improved the growth of rapeseed under cold stress (27-day cold treatment). In the YCD-treated group, the fresh root weight reached 0.06 g (Fig. 19(B)), exhibiting a >75% increase compared to conventional CD treatment and the CK group (Fig. 19(C)). In contrast, the fresh shoot weight increased by only ∼16%, highlighting the selective enhancement of root growth by YCDs. Furthermore, dry weight analyses of roots and shoots (Fig. 19(D) and (E)) revealed that YCD treatment induced a 108.89% increase in root dry weight relative to the CK group, while the shoot dry weight showed a smaller increment (33.33%). These findings conclusively demonstrate that YCD nanozymes selectively enhance root growth in rapeseed. This photoactive nanozyme-driven selectivity provides a novel strategy for improving crop adaptation to cold stress, advancing sustainable agricultural development.

Fig. 19 (A) Apparent morphology and root microscopic images of rapeseed under different treatments (CK, CDs, and YCDs). (B) Evaluation of fresh weight (B) and increment (C) of shoots and roots in rapeseed under cold stress (10 °C) after 27 days of different treatments. (D) Evaluation of dry weight (D) and increment (E) of shoots and roots in rapeseed seedlings.¹⁶⁴ Copyright 2025, Elsevier. (F) Phenotypic images of lettuce plants subjected to IMI stress under different treatments (H₂O or CDs) over 15 days.¹⁶⁷ Copyright 2025, Elsevier. (G) Steady-state kinetic analysis of Fe-CDs (left: substrate TMB; right: substrate H₂O₂). (H) Schematic illustration of the comparative analysis of O₂˙⁻ scavenging activity (SOD-like) between Fe-CDs and CDs (left); quantitative OH⁻ scavenging capacity of CDs and Fe-CDs via UV-vis method (right).¹⁶⁸ Copyright 2025, Elsevier.

Additionally, as previously mentioned, crops are susceptible to biotic stresses such as pest infestations. Traditional agriculture typically addresses insect problems through the application of pesticides like insecticides. However, to maintain efficacy, conventional pesticides may be prone to over-application and environmental accumulation of residues, potentially causing adverse impacts on crops and ecosystems.^165,166 Therefore, reducing pesticide residues has become a critical issue. A study synthesized CDs with cascade nanozyme activity, which effectively alleviated imidacloprid (IMI)-induced phytotoxicity in lettuce under pesticide stress.¹⁶⁷ CDs exhibit activities similar to those of SOD and POD. Through surface modification and analysis, it was confirmed that their SOD-like activity depends on the binding of –NH₂, –COOH, and –OH groups to O₂˙⁻, while the POD-like activity depends on the –COOH and CO groups. Under IMI stress, CDs can enhance various defense systems in lettuce and reduce the toxicity level of ROS. Specifically, the levels of O₂˙⁻, H₂O₂, and MDA were reduced by 26.77%, 48.52%, and 13.10%, respectively. Meanwhile, the nano-enzyme upregulated the expression of detoxification genes, resulting in a reduction in IMI residues in lettuce. Fig. 19(F) displays phenotypic images of lettuce plants subjected to high-concentration IMI stress following the application of 25 μg mL⁻¹ CDs. Compared to the control group, treatment with significantly alleviated developmental stunting and incomplete leaf expansion in IMI-stressed lettuce plants, restoring normal growth in the impaired specimens. Additionally, after CD treatment, the acceptable daily intake of IMI in lettuce was far lower than the reference dose, even being less than 18.0% under high-concentration IMI exposure. These results indicate that CDs have great potential in reducing pesticide residues and improving food safety.

Arsenic, as a highly toxic nonmetallic element, typically enters the environment through industrial emissions and agricultural fertilizers. Soil-accumulated arsenic generally enters food chains through plant uptake. Severe arsenic stress induces excessive ROS accumulation in plants, leading to reduced crop yields, quality deterioration, and potential human health risks through contaminated agricultural products. Therefore, developing effective strategies for arsenic pollution remediation and toxicity mitigation becomes imperative. Xie et al. synthesized iron-doped carbon dot (Fe-CD) nanozymes via a one-step hydrothermal method (average diameter = 2.01 nm; zeta potential = −34 mV).¹⁶⁸ By utilizing Fe³⁺ ions as catalytic active sites, they optimized the electronic structure and surface functional groups of carbon dots through a metal-doping strategy. Experimental results demonstrated that Fe-CDs exhibit superior multienzymatic activities, including POD-like, CAT-like, and SOD-like functionalities. As shown in Fig. 19(G), the K_m and V_max values for TMB and H₂O₂ were determined to be 8.56 mM and 2.04 × 10⁻⁵ M s⁻¹, and 6.72 mM and 2.82 × 10⁻⁵ M s⁻¹, respectively, demonstrating superior catalytic performance compared to other iron-based materials. In addition, Fe-CDs exhibited superior CAT-like and SOD activities, along with higher scavenging capacities for O₂˙⁻ (64.4% vs. 42.8%) and ˙OH (69.6% vs. 16.8%), compared to conventional CDs (Fig. 19(H)). These properties substantiate the effectiveness of Fe-CDs (applied at a spraying concentration of 300 mg L⁻¹) in mitigating arsenic toxicity in lettuce: not only effectively scavenging ROS under arsenic stress but also providing nutritional support for lettuce growth and development. This offers potential solutions for agricultural heavy metal contamination remediation and crop stress resistance enhancement. Additionally, Wang and colleagues engineered CeO₂ NPs with an irregular morphology (average particle size = 32.22 ± 7.57 nm, zeta potential = 16.47 ± 2.10 mV).¹⁶⁹ Their research demonstrated that these NPs exhibited remarkable enzyme-like activities, effectively alleviating As toxicity in pakchoi (Brassica chinensis L.). Foliar application of CeO₂ NPs with SOD-like and CAT-like activities significantly scavenged As-induced ROS overaccumulation in pak choi under As stress. Concurrently, the antioxidant defense system was modulated, resulting in substantial mitigation of phytotoxic effects. Additionally, CeO₂ NPs enhanced plant antioxidant capacity by modulating the GSH/oxidized glutathione (GSSG) ratio. Notably, foliar application of CeO₂ NPs not only reduced arsenic accumulation in pak choi (thereby minimizing its transfer through the food chain) but also substantially decreased human arsenic exposure risks via dietary intake of pak choi and snails. CeO₂ NPs also exhibited negligible self-translocation within the food chain, demonstrating exceptional biosafety.

5. Challenges and opportunities for agricultural nanozymes

With the advancement of agricultural modernization, nanozymes, as emerging materials, show great application prospects in the field of agriculture and are expected to provide new solutions for the problems in sustainable development of agriculture. Nanozymes play a key role in enhancing the adaptability of crops to adversity by regulating the physiological mechanisms of crops and enhancing their tolerance to adversities such as drought, salinity, and heavy metal pollution, thereby improving crop yield and quality. However, as with any emerging technology, nanozymes are facing both unprecedented opportunities and a series of challenges in agricultural applications.

5.1 Biosafety and toxicity issues

While considering the effects of nanozymes on plants, it is also important to consider their effects on the ecosystems in which the plants are found. The release of nanozymes in the environment may cause toxic effects on non-target organisms (such as beneficial microorganisms in the soil, insects, etc.), which may disrupt the ecological balance in severe cases. The metabolic pathways, accumulation patterns, and long-term toxic effects of nanozymes in plants are not well understood. Therefore, in-depth studies are needed to ensure that there is no or as little impact as possible on the ecosystems in which the plants live. In addition to this, greener and more environmentally friendly synthesis methods for nanozymes should be considered in order to better respond to sustainable development strategies in agriculture.

5.2 Stability and effectiveness issues

The activity and stability of nanozymes are susceptible to environmental factors such as humidity, temperature, and soil pH, which may compromise their stability in practical applications. Furthermore, although nanozymes can enhance plant stress resistance to some extent, the long-term durability of their stress-resistant effects under prolonged and complex stress conditions requires further improvement. Therefore, to better meet the diversified demands of agricultural production in complex ecological environments, researchers need to further investigate methods to enhance the stability and long-term effectiveness of nanozymes. This requires strengthening fundamental research on nanozymes, deepening the understanding of their mechanisms of action, and ensuring their stable functionality throughout the entire crop growth cycle.

5.3 Resistance and environmental accumulation

Similar to conventional pesticides, repeated use of nanozymes may lead to the development of resistance in harmful organisms, limiting their long-term application. Therefore, effective strategies are needed to delay or avoid the development of resistance. The unique physicochemical properties of nanozymes confer high catalytic activity, but this may make them susceptible to accumulation in environmental media, such as soil and water, and potentially harmful to the environment. The cumulative behavior of nanozymes in the environment and their long-term effects on the ecosystem are not yet clear. Therefore, in order to assess the risk of environmental accumulation of nanozymes, it is important to carry out long-term environmental monitoring and research.

5.4 Development of multifunctional nanozymes

By combining unique physicochemical properties and mimicking the catalytic activity of enzymes, nanozymes will provide a variety of simple but efficient and multifunctional platforms. In the future, it is important to consider the construction of nanozymes with multienzymatic characteristics and multifunctionality. They are expected to revolutionize the traditional agricultural production model from multiple dimensions and provide innovative solutions to cope with the complex and changing demands of agricultural production.

5.5 Real-world agricultural production

Although many research papers on the use of nanozymes for crop treatment have been reported, most of these studies were conducted in laboratory cultivation or sowing stage experiments. At present, there is a lack of research papers on the entire growth cycle of plants, and there is also a shortage of relevant research papers on application experiments in real fields. Therefore, in the future, researchers should consider narrowing the gap between experiments and real-world production. They should take into account various factors such as cost-effectiveness in agricultural practice and the complex real-world environment to better apply nanozyme materials to actual agricultural production.

Author contributions

N. Yin and Y. Wang proposed and supervised the project. R. Hou wrote the manuscript with comments from N. Yin, Y. Wang, S. Song and H. Zhang. All authors discussed the results and commented on the manuscript.

Conflicts of interest

There are no conflicts to declare.

Data availability

No primary research results, software or code have been included and no new data were generated or analysed as part of this review.

Acknowledgements

This work was supported by the financial aid from the National Key Research and Development Program of China (2020YFE0204500), the Basic Science Center Project of the National Natural Science Foundation of China (22388101), the National Natural Science Foundation of China (grant no. 22020102003, U23A20581, 52272169, 22393932, 52402352 and 52022094), the Program of Science and Technology Development Plan of Jilin Province of China (no. 20230508071RC) and the Youth Innovation Promotion Association of Chinese Academy of Sciences (grant Y2023067).

References

1. J.-K. Zhu, Cell, 2016, 167, 313–324.
2. R. Mittler, S. I. Zandalinas, Y. Fichman and F. Van Breusegem, Nat. Rev. Mol. Cell Biol., 2022, 23, 663–679.
3. R. Waadt, C. A. Seller, P.-K. Hsu, Y. Takahashi, S. Munemasa and J. I. Schroeder, Nat. Rev. Mol. Cell Biol., 2022, 23, 680–694.
4. H. Zhang, J. Zhu, Z. Gong and J.-K. Zhu, Nat. Rev. Genet., 2021, 23, 104–119.
5. B. D. Collins and G. M. Stock, Nat. Geosci., 2016, 9, 395–400.
6. A. M. Milner and I. L. Boyd, Science, 2017, 357, 1232–1234.
7. A. E. Larsen, F. Noack and L. C. Powers, Science, 2024, 383, 1308.
8. M. Kah, R. S. Kookana, A. Gogos and T. D. Bucheli, Nat. Nanotechnol., 2018, 13, 677–684.
9. D. Wang, N. B. Saleh, A. Byro, R. Zepp, E. Sahle-Demessie, T. P. Luxton, K. T. Ho, R. M. Burgess, M. Flury, J. C. White and C. Su, Nat. Nanotechnol., 2022, 17, 347–360.
10. N. Kandhol, V. P. Singh, S. Pandey, S. Sharma, L. Zhao, F. J. Corpas, Z.-H. Chen, J. C. White and D. K. Tripathi, Trends Plant Sci., 2024, 29, 1310–1318.
11. H. Chhipa, Environ. Chem. Lett., 2016, 15, 15–22.
12. S.-Y. Kwak, T. T. S. Lew, C. J. Sweeney, V. B. Koman, M. H. Wong, K. Bohmert-Tatarev, K. D. Snell, J. S. Seo, N.-H. Chua and M. S. Strano, Nat. Nanotechnol., 2019, 14, 447–455.
13. H. Karimi-Maleh, M. Ghalkhani, Z. Saberi Dehkordi, M. Mohsenpour Tehran, J. Singh, Y. Wen, M. Baghayeri, J. Rouhi, L. Fu and S. Rajendran, J. Ind. Eng. Chem., 2024, 129, 105–123.
14. M. Kah, L. J. Johnston, R. S. Kookana, W. Bruce, A. Haase, V. Ritz, J. Dinglasan, S. Doak, H. Garelick and V. Gubala, Nat. Nanotechnol., 2021, 16, 955–964.
15. R. Wang, F. x Luan, Z. s Wang, X. c Liu, X. g Zhang, K. Wang, W. Mu, F. Liu and D. x Zhang, Adv. Mater., 2024, 36, 2409839.
16. A. Yayci, T. Sassmann, A. Boes, F. Jakob, A. Töpel, A. Loreth, C. Rauch, A. Pich and U. Schwaneberg, Angew. Chem., Int. Ed., 2024, 63, e202319832.
17. M. Kah, N. Tufenkji and J. C. White, Nat. Nanotechnol., 2019, 14, 532–540.
18. Y. Wang, X. Jia, S. An, W. Yin, J. Huang and X. Jiang, Adv. Mater., 2023, 36, 2301810.
19. T. Ahmed, M. Noman, H. Jiang, M. Shahid, C. Ma, Z. Wu, M. M. Nazir, M. A. Ali, J. C. White, J. Chen and B. Li, Nano Today, 2022, 45, 101547.
20. Z. Xiao, N. Fan, W. Zhu, H.-L. Qian, X.-P. Yan, Z. Wang and S. Rasmann, ACS Nano, 2023, 17, 3107–3118.
21. D. Jiang, D. Ni, Z. T. Rosenkrans, P. Huang, X. Yan and W. Cai, Chem. Soc. Rev., 2019, 48, 3683–3704.
22. F. Manea, F. B. Houillon, L. Pasquato and P. Scrimin, Angew. Chem., Int. Ed., 2004, 43, 6165–6169.
23. L. Gao, J. Zhuang, L. Nie, J. Zhang, Y. Zhang, N. Gu, T. Wang, J. Feng, D. Yang, S. Perrett and X. Yan, Nat. Nanotechnol., 2007, 2, 577–583.
24. M. Zandieh and J. Liu, Adv. Mater., 2023, 36, 2211041.
25. L. Mei, S. Zhu, Y. Liu, W. Yin, Z. Gu and Y. Zhao, Chem. Eng. J., 2021, 418, 129431.
26. H. Wei, L. Gao, K. Fan, J. Liu, J. He, X. Qu, S. Dong, E. Wang and X. Yan, Nano Today, 2021, 40, 101269.
27. X. Shen, Z. Yang, X. Dai, W. Feng, P. Li and Y. Chen, Adv. Mater., 2024, 36, 2402745.
28. H. Wu, N. Tito and J. P. Giraldo, ACS Nano, 2017, 11, 11283–11297.
29. Y. Liu, D. Liu, X. Han, Z. Chen, M. Li, L. Jiang and J. Zeng, ACS Nano, 2024, 18, 31188–31203.
30. Z. Wang, R. Zhang, X. Yan and K. Fan, Mater. Today, 2020, 41, 81–119.
31. Y. Ai, M. Q. He, H. Sun, X. Jia, L. Wu, X. Zhang, H. B. Sun and Q. Liang, Adv. Mater., 2023, 35, 2302335.
32. H. Fan, R. Zhang, K. Fan, L. Gao and X. Yan, ACS Nano, 2024, 18, 2533–2540.
33. L. Li, S. J. Cao, Z. H. Wu, R. Q. Guo, L. Xie, L. Y. Wang, Y. J. Tang, Q. Li, X. L. Luo, L. Ma, C. Cheng and L. Qiu, Adv. Mater., 2022, 34, 2108646.
34. H. Ding, B. Hu, B. Zhang, H. Zhang, X. Yan, G. Nie and M. Liang, Nano Res., 2020, 14, 570–583.
35. L. Huang, X. He, J. Hu, C. Qin, C. Huang, Y. Tang, F. Zhong, X. Kong and X. Wei, ACS Nano, 2024, 18, 33105–33118.
36. N. Singh, M. A. Savanur, S. Srivastava, P. D’Silva and G. Mugesh, Angew. Chem., Int. Ed., 2017, 56, 14267–14271.
37. G. Fang, W. F. Li, X. M. Shen, J. M. Perez-Aguilar, Y. Chong, X. F. Gao, Z. F. Chai, C. Y. Chen, C. C. Ge and R. H. Zhou, Nat. Commun., 2018, 9, 129.
38. D. Wang, J. Wang, X. J. Gao, H. Ding, M. Yang, Z. He, J. Xie, Z. Zhang, H. Huang, G. Nie, X. Yan and K. Fan, Adv. Mater., 2023, 36, 2310033.
39. Y. Zhao, S. Zhao, Y. Du, Z. Gao, Y. Li, H. Ma, H. Li, X. Ren, Q. Fan, D. Wu and Q. Wei, Adv. Mater., 2025, 37, 2418731.
40. J. Zhang, Z. Wang, X. Lin, X. Gao, Q. Wang, R. Huang, Y. Ruan, H. Xu, L. Tian, C. Ling, R. Shi, S. Xu, K. Chen and Y. Wu, Angew. Chem., Int. Ed., 2024, 64, e202416686.
41. Y. Lin, X. Ren, F. Xuan and Z. Liu, Adv. Compos. Hybrid Mater., 2024, 8, 68.
42. Q. Qiao, Z. Liu, F. Hu, Z. Xu, Y. Kuang and C. Li, Adv. Funct. Mater., 2024, 35, 2414837.
43. J. Liu, S. Dong, S. Gai, S. Li, Y. Dong, C. Yu, F. He and P. Yang, ACS Nano, 2024, 18, 23579–23598.
44. Y. Dang, G. Wang, G. Su, Z. Lu, Y. Wang, T. Liu, X. Pu, X. Wang, C. Wu, C. Song, Q. Zhao, H. Rao and M. Sun, ACS Nano, 2022, 16, 4536–4550.
45. C. Ge, G. Fang, X. Shen, Y. Chong, W. G. Wamer, X. Gao, Z. Chai, C. Chen and J.-J. Yin, ACS Nano, 2016, 10, 10436–10445.
46. T. R. Shojaei, M. A. M. Salleh, M. Tabatabaei, H. Mobli, M. Aghbashlo, S. A. Rashid and T. Tan, Synthesis, Technology and Applications of Carbon Nanomaterials, 2019, pp. 247–277 DOI:10.1016/b978-0-12-815757-2.00011-5.
47. K. A. Abd-Elsalam, Carbon Nanomaterials for Agri-Food and Environmental Applications, 2020, pp. 1–18 DOI:10.1016/b978-0-12-819786-8.00001-3.
48. Y. Cui, K. Wang and C. Zhang, ACS Nano, 2024, 18, 10829–10839.
49. Y. Sun, B. Xu, X. Pan, H. Wang, Q. Wu, S. Li, B. Jiang and H. Liu, Coord. Chem. Rev., 2023, 475, 214896.
50. V. R. Raphey, T. K. Henna, K. P. Nivitha, P. Mufeedha, C. Sabu and K. Pramod, Mater. Sci. Eng., C, 2019, 100, 616–630.
51. M. Safdar, W. Kim, S. Park, Y. Gwon, Y.-O. Kim and J. Kim, J. Nanobiotechnol., 2022, 20, 275.
52. H. Hou, X. Zheng, H. Zhang, M. Yue, Y. Hu, H. Zhou, Q. Wang, C. Xie, P. Wang and L. Li, IEEE Trans. NanoBiosci., 2017, 16(7), 563–570.
53. X. Li, S. Sun, S. Guo and X. Hu, Environ. Sci. Technol., 2021, 55, 9938–9948.
54. P. Zhang, Z. Guo, W. Luo, F. A. Monikh, C. Xie, E. Valsami-Jones, I. Lynch and Z. Zhang, Environ. Sci. Technol., 2020, 54, 3181–3190.
55. L. Duo, Y. Wang and S. Zhao, Ecotoxicol. Environ. Saf., 2022, 229, 113076.
56. Z. Chen, Y. Yu, Y. Gao and Z. Zhu, ACS Nano, 2023, 17, 13062–13080.
57. H. Fan, J. Zheng, J. Xie, J. Liu, X. Gao, X. Yan, K. Fan and L. Gao, Adv. Mater., 2023, 36, 2300387.
58. Y. Huang, J. Ren and X. Qu, Chem. Rev., 2019, 119, 4357–4412.
59. B. Seong, J. Kim, W. Kim, S. H. Lee, X.-H. Pham and B.-H. Jun, Int. J. Mol. Sci., 2021, 22, 10382.
60. X. Cao, L. Yue, C. Wang, X. Luo, C. Zhang, X. Zhao, F. Wu, J. C. White, Z. Wang and B. Xing, ACS Nano, 2022, 16, 1170–1181.
61. Y. Huang, S. Peng, Y. Liu, G. Feng, Z. Ding, B. Xiang, L. Zheng, H. Cheng, S. Liu, H. Yao and J. Fang, J. Agric. Food Chem., 2024, 72, 23008–23023.
62. P. Hu, J. An, M. M. Faulkner, H. Wu, Z. Li, X. Tian and J. P. Giraldo, ACS Nano, 2020, 14, 7970–7986.
63. A. Avellan, F. Schwab, A. Masion, P. Chaurand, D. Borschneck, V. Vidal, J. Rose, C. Santaella and C. Levard, Environ. Sci. Technol., 2017, 51, 8682–8691.
64. L. Chen, L. Zhu, H. Cheng, W. Xu, G. Li, Y. Zhang, J. Gu, L. Chen, Z. Xie, Z. Li and H. Wu, ACS Nano, 2024, 18, 23154–23167.
65. J. Ma, Y. Zhou, J. Li, Z. Song and H. Han, J. Nanobiotechnol., 2022, 20, 168.
66. M. Li, L. Gao, J. C. White, C. L. Haynes, T. L. O’Keefe, Y. Rui, S. Ullah, Z. Guo, I. Lynch and P. Zhang, Nat. Nanotechnol., 2023, 18, 688–691.
67. L. Gao, H. Wei, S. Dong and X. Yan, Adv. Mater., 2024, 36, 2305249.
68. S. Deng, Y. Hao, L. Yang, T. Yu, X. Wang, H. Liu, Y. Liu and M. Xie, Biosens. Bioelectron., 2025, 278, 117339.
69. J. Zhang, Z. Wang, X. Lin, X. Gao, Q. Wang, R. Huang, Y. Ruan, H. Xu, L. Tian, C. Ling, R. Shi, S. Xu, K. Chen and Y. Wu, Angew. Chem., Int. Ed., 2024, 64, e202416686.
70. M. Chen, A. Qileng, S. Chen, H. Huang, Z. Xu, W. Liu and Y. Liu, Adv. Funct. Mater., 2024, 34, 2423643.
71. Y. Shen, R. Xing, X. Xu, Y. Wang, R. Huang, R. Su, M. D. Dickey, W. Qi and J. Kong, Matter, 2025, 8, 102159.
72. H. Shan, J. Shi, T. Chen, Y. Cao, Q. Yao, H. An, Z. Yang, Z. Wu, Z. Jiang and J. Xie, ACS Nano, 2023, 17, 2368–2377.
73. Z. Yu, Z. Xu, R. Zeng, M. Xu, M. Zou, D. Huang, Z. Weng and D. Tang, Angew. Chem., Int. Ed., 2024, 64, e202420200.
74. M. Chen, A. Qileng, S. Chen, H. Huang, Z. Xu, W. Liu and Y. Liu, Adv. Funct. Mater., 2024, 34, 2402552.
75. M. Jabran, M. A. Ali, S. Muzammil, A. Zahoor, F. Ali, S. Hussain, G. Muhae-Ud-Din, M. Ijaz and L. Gao, Chem. Biol. Technol. Agric., 2024, 11, 75.
76. Y. Hao, C. Ma, Z. Zhang, Y. Song, W. Cao, J. Guo, G. Zhou, Y. Rui, L. Liu and B. Xing, Environ. Pollut., 2018, 232, 123–136.
77. Y. Li, W. Li, X. Yang, Y. Kang, H. Zhang, Y. Liu and B. Lei, ACS Appl. Nano Mater., 2020, 4, 113–120.
78. D. Li, D. Dai, G. Xiong, S. Lan and C. Zhang, Small, 2022, 19, 2205870.
79. Q. Liu, A. Zhang, R. Wang, Q. Zhang and D. Cui, Nano-Micro Lett., 2021, 13, 154.
80. H. Bidi, H. Fallah, Y. Niknejad and D. Barari Tari, Plant Physiol. Biochem., 2021, 163, 348–357.
81. H. Tombuloglu, Y. Slimani, G. Tombuloglu, M. Almessiere and A. Baykal, Chemosphere, 2019, 226, 110–122.
82. M. Shen, W. Liu, A. Zeb, J. Lian, J. Wu and M. Lin, J. Environ. Manage., 2022, 306, 114454.
83. Z. Wang, J. Wu, J.-J. Zheng, X. Shen, L. Yan, H. Wei, X. Gao and Y. Zhao, Nat. Commun., 2021, 12, 6866.
84. M. Rizwan, S. Ali, M. Zia ur Rehman, M. Adrees, M. Arshad, M. F. Qayyum, L. Ali, A. Hussain, S. A. S. Chatha and M. Imran, Environ. Pollut., 2019, 248, 358–367.
85. Y. Yu, Y. Zhang, Y. Wang, W. Chen, Z. Guo, N. Song and M. Liang, Nano Res., 2023, 16, 10763–10769.
86. W. Gao, J. He, L. Chen, X. Meng, Y. Ma, L. Cheng, K. Tu, X. Gao, C. Liu, M. Zhang, K. Fan, D.-W. Pang and X. Yan, Nat. Commun., 2023, 14, 160.
87. C. Liu, W. Fan, W. X. Cheng, Y. Gu, Y. Chen, W. Zhou, X. F. Yu, M. Chen, M. Zhu, K. Fan and Q. Y. Luo, Adv. Funct. Mater., 2023, 33, 2213856.
88. Z. Wang, X. Shen and X. Gao, J. Phys. Chem. C, 2021, 125, 23098–23104.
89. Y. Gao, X. Gao, H. Hou, Z. Qu, H. Li, B. Du and P. Tang, Sens. Actuators, B, 2024, 404, 135280.
90. Z. Lin, T. Dong, L. Niu, X. Zhang, M. Wang, X. Liu, Y. Cai and A. Liu, Chem. Eng. J., 2024, 482, 148775.
91. F. Zhang, Z. Chen, J. Liu, C. Li, B. Jiang, J. Shen, Y. Liu and Z. Xu, Chem. Eng. J., 2024, 492, 152328.
92. B. Jiang, D. Duan, L. Gao, M. Zhou, K. Fan, Y. Tang, J. Xi, Y. Bi, Z. Tong, G. F. Gao, N. Xie, A. Tang, G. Nie, M. Liang and X. Yan, Nat. Protoc., 2018, 13, 1506–1520.
93. J.-J. Zheng, F. Zhu, N. Song, F. Deng, Q. Chen, C. Chen, J. He, X. Gao and M. Liang, Nat. Protoc., 2024, 19, 3470–3488.
94. Z. Li, B. Ding, J. Li, H. Chen, J. Zhang, J. Tan, X. Ma, D. Han, P. A. Ma and J. Lin, Angew. Chem., Int. Ed., 2024, 64, e202413661.
95. S. Ji, B. Jiang, H. Hao, Y. Chen, J. Dong, Y. Mao, Z. Zhang, R. Gao, W. Chen, R. Zhang, Q. Liang, H. Li, S. Liu, Y. Wang, Q. Zhang, L. Gu, D. Duan, M. Liang, D. Wang, X. Yan and Y. Li, Nat. Catal., 2021, 4, 407–417.
96. S. Zhang, X. J. Gao, Y. Ma, K. Song, M. Ge, S. Ma, L. Zhang, Y. Yuan, W. Jiang, Z. Wu, L. Gao, X. Yan and B. Jiang, Nat. Commun., 2024, 15, 10605.
97. J. Feng, X. Yang, T. Du, L. Zhang, P. Zhang, J. Zhuo, L. Luo, H. Sun, Y. Han, L. Liu, Y. Shen, J. Wang and W. Zhang, Adv. Sci., 2023, 10, 2303078.
98. G. Noctor, J.-P. Reichheld and C. H. Foyer, Semin. Cell Dev. Biol., 2018, 80, 3–12.
99. Z. Ding, Q. Song, G. Wang, Z. Zhong, G. Zhong, H. Li, Y. Chen, X. Zhou, L. Liu and S. Yang, RSC Adv., 2024, 14, 17571–17582.
100. Y. Chen, B. Jiang, H. Hao, H. Li, C. Qiu, X. Liang, Q. Qu, Z. Zhang, R. Gao, D. Duan, S. Ji, D. Wang and M. Liang, Angew. Chem., Int. Ed., 2023, 62, e202301879.
101. S. M. Jones and E. I. Solomon, Cell. Mol. Life Sci., 2015, 72, 869–883.
102. R. G. Hadt, S. I. Gorelsky and E. I. Solomon, J. Am. Chem. Soc., 2014, 136, 15034–15045.
103. X. Zhang, D. Wu, Y. Wu and G. Li, Biosens. Bioelectron., 2021, 172, 112776.
104. J. Wang, R. Huang, W. Qi, R. Su, B. P. Binks and Z. He, Appl. Catal., B, 2019, 254, 452–462.
105. S. Liang, X.-L. Wu, J. Xiong, X. Yuan, S.-L. Liu, M.-H. Zong and W.-Y. Lou, Chem. Eng. J., 2022, 450, 138220.
106. Y. Wang, D. Wang, Q. Mu, Y. Zhai, J. Hai, Y. Ji and R. Li, Chem. Eng. J., 2024, 502, 158021.
107. P. Villeneuve, J. M. Muderhwa, J. Graille and M. J. Haas, J. Mol. Catal. B: Enzym., 2000, 9, 113–148.
108. Y. M. Soh, I. F. Davidson, S. Zamuner, J. Basquin, F. P. Bock, M. Taschner, J. W. Veening, P. De Los Rios, J. M. Peters and S. Gruber, Science, 2019, 366, 1129–1133.
109. C. C. Akoh, G.-C. Lee, Y.-C. Liaw, T.-H. Huang and J.-F. Shaw, Prog. Lipid Res., 2004, 43, 534–552.
110. B. O’Leary, G. M. Preston and L. J. Sweetlove, Mol. Plant, 2014, 7, 231–243.
111. Y.-Q. Gao, P. Jimenez-Sandoval, S. Tiwari, S. Stolz, J. Wang, G. Glauser, J. Santiago and E. E. Farmer, Cell, 2023, 186, 1337–1351.
112. Y. Sun and R. P. Jarvis, Annu. Rev. Plant Biol., 2023, 74, 259–283.
113. W. Vandenende, B. Deconinck and A. Vanlaere, Trends Plant Sci., 2004, 9, 523–528.
114. T. Klein, U. Eckhard, A. Dufour, N. Solis and C. M. Overall, Chem. Rev., 2018, 118, 261–292.
115. A. A. Vernekar, T. Das and G. Mugesh, Angew. Chem., Int. Ed., 2015, 55, 1412–1416.
116. R. Walther, A. K. Winther, A. S. Fruergaard, W. van den Akker, L. Sørensen, S. M. Nielsen, M. T. Jarlstad Olesen, Y. Dai, H. S. Jeppesen, P. Lamagni, A. Savateev, S. L. Pedersen, C. K. Frich, C. Vigier-Carrière, N. Lock, M. Singh, V. Bansal, R. L. Meyer and A. N. Zelikin, Angew. Chem., Int. Ed., 2018, 58, 278–282.
117. Y. Lin, J. Ren and X. Qu, Adv. Mater., 2014, 26, 4200–4217.
118. T. Chen, Y. Lu, X. Xiong, M. Qiu, Y. Peng and Z. Xu, Adv. Colloid Interface Sci., 2024, 323, 103072.
119. Z. Zhang, Z. Chen, Y. Zhang, Z. Wang, D. Chen, J. Liu and Z. Zhu, Coord. Chem. Rev., 2025, 524, 216340.
120. Z. Yu, J. Chen, D. Chao, X. Sun, L. Liu and S. Dong, Appl. Catal., B, 2023, 330, 122639.
121. M. D. Arifuzzaman, I. Bose, F. Bahrami and Y. Zhao, Chem Catal., 2022, 2, 2049–2065.
122. J. Sheng, Y. Wu, H. Ding, K. Feng, Y. Shen, Y. Zhang and N. Gu, Adv. Mater., 2023, 36, 2211210.
123. Y. Jiang, Z. Chen, N. Sui and Z. Zhu, J. Am. Chem. Soc., 2024, 146, 7565–7574.
124. X. Ye, L. Xia, H. Yang, J. Xu, T. Liu, L. Wang, S. Zhang, Y. Chen, D. Du and W. Feng, Mater. Today, 2023, 68, 148–163.
125. L. Shang, Y. Yu, Y. Jiang, X. Liu, N. Sui, D. Yang and Z. Zhu, ACS Nano, 2023, 17, 15962–15977.
126. X. Huang, S. Chen, W. Li, L. Tang, Y. Zhang, N. Yang, Y. Zou, X. Zhai, N. Xiao, W. Liu, P. Li and C. Xu, Nat. Chem. Biol., 2021, 17, 549–557.
127. K. Sawinski, S. Mersmann, S. Robatzek and M. Böhmer, Mol. Plant-Microbe Interact., 2013, 26, 626–632.
128. Z. Chen, J. Niu, Z. Guo, X. Sui, N. Xu, H. A. Kareem, M. U. Hassan, M. Yan, Q. Zhang, J. Cui, J. Kang, Z. Wang, F. Mi, D. Karagić and Q. Wang, Environ. Sci.-Nano, 2021, 8, 2731–2748.
129. B. Wu, F. Qi and Y. Liang, Trends Plant Sci., 2023, 28, 1124–1131.
130. L. Zhao, T. Bai, H. Wei, J. L. Gardea-Torresdey, A. Keller and J. C. White, Nat. Food, 2022, 3, 829–836.
131. V. Demidchik, Environ. Exp. Bot., 2015, 109, 212–228.
132. Y. J. Jia, L. Kang, Y. L. Wu, C. R. Zhou, D. Li, J. Q. Li and C. P. Pan, J. Agric. Food Chem., 2023, 71, 13595–13611.
133. F. Liu, G. Zhang, C. L. Zhang, W. L. Zhou, X. J. Xu, Q. Y. Shou, F. Yuan, Q. Li, H. J. Huang, J. H. Hu, W. J. Jiang, J. M. Qin, W. G. Ye and P. L. Dai, Environ. Res., 2023, 219, 115097.
134. J. Prathiksha, R. K. Narasimhamurthy, H. S. Dsouza and K. D. Mumbrekar, Mol. Biol. Rep., 2023, 50, 5465–5479.
135. Y. Wang, Y. Liang, X. Ma, Y. Dong, M. Klakong, A. Wang, M. Chen, T. Fan, X. Xu, P. Xiao and W. Ding, Ind. Crops Prod., 2024, 220, 119269.
136. S. Li, Y. Long, G. Deng, Y. Men, F. Lu, Z. Wang, J. Li and H. Han, Environ. Sci.-Nano, 2025, 12, 701–715.
137. C. Li, Y. Han, T. Gao, J. Zhang, D.-X. Xu and Y. Wāng, Environ. Chem. Lett., 2022, 21, 1141–1176.
138. R. Gao, L. Xu, M. Sun, M. Xu, C. Hao, X. Guo, F. M. Colombari, X. Zheng, P. Král, A. F. de Moura, C. Xu, J. Yang, N. A. Kotov and H. Kuang, Nat. Catal., 2022, 5, 694–707.
139. Q. Zeng, C. Yu, X. Chang, Y. Wan, Y. Ba, C. Li, H. Lv, Z. Guo, T. Cai, Z. Ren, Y. Qin, Y. Zhang, K. Ma, J. Li, S. He and H. Wan, Chem. Eng. J., 2022, 446, 137074.
140. M. Jakl, S. Ćavar Zeljković, I. Kovač, K. Bělonožníková and J. Jaklová Dytrtová, Chemosphere, 2021, 277, 130242.
141. P. Singh and S. M. Prasad, Sci. Total Environ., 2018, 630, 839–848.
142. Y. Song and C. H. Haney, Nat. Plants, 2021, 7, 994–995.
143. M. Rezayian, V. Niknam and M. Arabloo, Sci. Rep., 2023, 13, 9628.
144. S. Shirvani-Naghani, S. Fallah, L. R. Pokhrel and A. Rostamnejadi, Sci. Rep., 2024, 14, 27898.
145. Q. Chen, X. Cao, X. Nie, Y. Li, T. Liang and L. Ci, J. Hazard. Mater., 2022, 423, 127260.
146. J. Liu, S. Z. Qiao, Q. H. Hu and G. Q. Lu, Small, 2011, 7, 425–443.
147. M. Zia-ur-Rehman, A. Naeem, H. Khalid, M. Rizwan, S. Ali and M. Azhar, Nanomaterials in Plants, Algae, and Microorganisms, 2018, pp. 221–238 DOI:10.1016/b978-0-12-811487-2.00010-4.
148. S. Chen, H. Liu, Z. Yangzong, J. L. Gardea-Torresdey, J. C. White and L. Zhao, Environ. Sci. Technol., 2023, 57, 19932–19941.
149. N. G. M. Palmqvist, G. A. Seisenbaeva, P. Svedlindh and V. G. Kessler, Nanoscale Res. Lett., 2017, 12, 631.
150. M. S. Haydar, S. Ali, P. Mandal, D. Roy, M. N. Roy, S. Kundu, S. Kundu and C. Choudhuri, Sci. Rep., 2023, 13, 11040.
151. E. van Zelm, Y. Zhang and C. Testerink, Annu. Rev. Plant Biol., 2020, 71, 403–433.
152. Z. Li, L. Zhu, F. Zhao, J. Li, X. Zhang, X. Kong, H. Wu and Z. Zhang, Front. Plant Sci., 2022, 13, 843994.
153. X. Yan, S. Chen, Z. Pan, W. Zhao, Y. Rui and L. Zhao, ACS Nano, 2022, 17, 492–504.
154. J. Gong, Q. Liu, L. Cai, Q. Yang, Y. Tong, X. Chen, S. Kotha, X. Mao and W. He, ACS Sustainable Chem. Eng., 2023, 11, 4237–4247.
155. L. Lu, M. Huang, Y. Huang, P. F. X. Corvini, R. Ji and L. Zhao, Environ. Sci.-Nano, 2020, 7, 1692–1703.
156. H. Liu, C. Li, L. Cai, X. Zhang, J. Si, Y. Tong, L. Wang, Z. Xu and W. He, J. Agric. Food Chem., 2024, 72, 24311–24324.
157. H. Zhao, R. Zhang, X. Yan and K. Fan, J. Mater. Chem. B, 2021, 9, 6939–6957.
158. Y. Liu, X. Cao, L. Yue, C. Wang, M. Tao, Z. Wang and B. Xing, Environ. Pollut., 2022, 299, 118900.
159. D. Feng, R. Wang, X. Sun, L. N. Liu, P. Liu, J. Tang, C. Zhang and H. Liu, Sci. Total Environ., 2023, 897, 165397.
160. B. B. Abdallah, X. Zhang, I. Andreu, B. D. Gates, R. El Mokni, S. Rubino, A. Landoulsi and A. Chatti, J. Hazard. Mater., 2020, 386, 121644.
161. M. Wang, C. Mu, X. Lin, W. Ma, H. Wu, D. Si, C. Ge, C. Cheng, L. Zhao, H. Li and D. Zhou, Environ. Sci. Technol., 2024, 58, 6900–6912.
162. C. J. Weiser, Science, 1970, 169, 1269–1278.
163. H. Wu, X. Wan, J. Niu, Y. Cao, S. Wang, Y. Zhang, Y. Guo, H. Xu, X. Xue, J. Yao, C. Zhu, Y. Li, Q. Li, T. Lu, H. Yu and W. Jiang, J. Nanobiotechnol., 2024, 22, 268.
164. Z. Ding, W. Xu, Y. Feng, Y. Li, X. Ma, Z. Zhou, K. Chen, A. A. Shah, Q. Wang, X. Ren, J. Liang, Y. Huang, Q. Xiao and Z. Zhang, Chem. Eng. J., 2025, 508, 160428.
165. Q. Shan, M. Liu, R. Li, Q. Shi, Y. Li and B. Gong, Sci. Total Environ., 2022, 835, 155404.
166. M. Yang, Y. Wang, G. Yang, Y. Wang, F. Liu and C. Chen, Trends Food Sci. Technol., 2024, 144, 104340.
167. F. Chen, Z. Zhou, N. Yang, Q. Jiang, X. Zhang, H. Zhang, Y. Zheng, W. Li and B. Lei, Food Chem., 2025, 464, 141926.
168. M. Xie, F. Li, Y. Li, K. Qian, Y. Liang, B. Lei, Y. Liu, J. Cui and Y. Xiao, Chem. Eng. J., 2025, 506, 159956.
169. Y. Wang, C. Ma, F. Dang, L. Zhao, D. Zhou and X. Gu, J. Hazard. Mater., 2024, 462, 132770.

---