Evaluation of Justicia adhatoda-Incorporated Tin Oxide Nanoparticles and CuSe-Doped SnO2 Nanocomposites: Characterization and Enhancement of Antibacterial, Antioxidant, and Cytotoxic Activities in an In Vitro Approach

Abstract

In this study we investigate the green synthesis and biological evaluation of -SnO2 NPs and CuSe doped SnO2 NCs for antibacterial activity, antioxidant activity and cytotoxicity. This is the first report demonstrating the green synthesis of CuSe doped SnO2 NCs using Justicia adhatoda extract, exhibiting synergistically enhanced antioxidant, antimicrobial and anticancer properties. The SnO2 and CuSe NPs were synthesised using Malabar nut (J. adhatoda) plant leaf extract, with CuSe doping concentrations optimized for enhanced efficacy. The synthesized nanoparticles were characterized by P-XRD, UV-Visible, TEM, HRSEM-EDX, HRSEM-EDS, XPS, and FTIR spectra. UV–Visible spectroscopy showed a band gap reduction from 3.6 eV (SnO2) to 2.8 eV (30% CuSe doped SnO2 NCs), indicating the dopant material effectively doped into SnO2 NPs as well as these bandgaps change enhanced electronic interactions contributing to biological activity. TEM analysis revealed an average particle size of 45.51 nm for SnO2 and 17.36 nm for CuSe NPs. The -chemical present on the surface of the NPs confirmed by FTIR and XPS. The 30% CuSe-doped SnO2 NCs exhibited the highest antibacterial activity at 100 µg/mL concentration, showing enhanced inhibition zones against Gram-positive bacterium Staphylococcus aureus (13 mm), and Gram-negative bacteria Escherichia coli (10 mm), Pseudomonas aeruginosa (10 mm), and Klebsiella pneumoniae (8) compared to SnO2 NPs. The nanocomposites also demonstrated strong antioxidant potential, with a DPPH free radical scavenging IC50 value of 56.49 µg/mL compared to 99.58 µg/mL for SnO2 NPs. Cytotoxicity studies against the HepG2 cell line revealed an IC50 of 120.57 µg/mL, surpassing previously reported values. These results demonstrate the potential of eco-friendly 30% CuSe-doped SnO2 NCs for future applications in drug development, highlighting and their promise for biomedical and pharmaceutical applications, paving the way for sustainable drug development.