Self-assembled peptide nanosheets functionalized with Fe3O4 nanoparticles with enhanced nanozymatic activity for sensitive colorimetric detection and selective adsorption of Hg2+

Abstract

The determination and adsorption of Hg²⁺ in/from a solution system is of great significance in environmental monitoring and remediation. In this study, we present the design and synthesis of peptide nanosheets (PNSs) functionalized with Fe₃O₄ magnetic nanoparticles (MNPs) and develop a simple, fast, and naked-eye observable colorimetric detection nanoplatform and a sustainable adsorption system for Hg²⁺. For the aims, a functional peptide molecule with motif-designed sequence, Fmoc-FKKGSHC, is used for the formation of PNSs with uniform size by tailoring the molecular self-assembly process. The created PNSs are further modified with –COOH-functionalized Fe₃O₄ (c-Fe₃O₄) MNPs through electrostatic interaction to form two-dimensional (2D) PNSs/c-Fe₃O₄ nanocomposites. Due to the unique nanozymatic activity of c-Fe₃O₄ and specific interactions between PNSs and Hg²⁺, the fabricated PNSs/c-Fe₃O₄ nanocomposites not only exhibit high anti-interference ability towards Hg²⁺ detection with high sensitivity and a low detection limit of 2.52 nM but also reveal good adsorption efficiency towards Hg²⁺ at a concentration of 0–100 ppm as a recyclable and sustainable adsorption material. This study not only presents green strategies to prepare functional peptide nanomaterials via regulating molecular self-assembly and biomimetic synthesis but also inspires potential applications of peptide-inspired nanomaterials in biological analysis and environmental monitoring.