α-Amylase-Assisted Microwave Synthesis of SnO 2 Nanostructures with Defect-Related Surface Chemistry for Photocatalytic and Biological Applications

A rapid and sustainable microwave-assisted green synthesis was developed for α-amylase-assisted tin oxide nanoparticles (ZjL-SnO 2 NPs) using Ziziphus jujuba leaf extract as a natural reducing, capping, and stabilizing agent. The biomacromolecule-mediated route generated highly crystalline, spherical ZjL-SnO 2 NPs, as confirmed by XRD, FTIR, XPS, SEM, HRTEM, and BET analyses. The a-amylase-assisted biomolecular route influenced nanoparticle nucleation, surface hydroxylation, and defect-related surface chemistry, which may contribute to improved interfacial charge transfer and redox activity. Under visible-light irradiation, the ZjL-SnO 2 NPs exhibited considerable photocatalytic performance, achieving ≈93% methylene blue (MB) degradation within 35 min, highlighting their potential as photoactive materials for water decontamination. Furthermore, ZjL-SnO 2 NPs showed remarkable antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria as well as antioxidant activity (≈88% DPPH radical scavenging). The multifunctionality of ZjL-SnO 2 NPs was demonstrated by their combination of photoreactive, antibacterial, and antioxidative properties. This is the basis for safely and scalably producing enzyme-assisted metal-oxide nanostructures. These nanostructures have enormous potential for use in water treatment, and antimicrobial applications.