Green Synthesis of Silver-Decorated Zinc-Based Nanostructures Mediated by Russula sanguinea and Their Biofunctional Properties

The green synthesis of nanomaterials using biological resources has emerged as a sustainable alternative to conventional chemical routes. In this study, the wild ectomycorrhizal mushroom <i>Russula sanguinea</i> (Rs) was employed as a natural reducing and stabilizing agent for the biosynthesis of silver-decorated zinc-based nanostructures (Ag-ZnNSs/Rs). The formation and physicochemical properties of the nanostructures were systematically characterized using UV-Vis spectroscopy, FT-IR spectroscopy, SEM, TEM, and EDX analysis. Transmission electron microscopy revealed predominantly spherical nanoparticles with good dispersion, and quantitative analysis of 227 individual particles demonstrated an average diameter of 19.36 ± 7.89 nm (range: 10.92-61.00 nm). FT-IR analysis confirmed the involvement of fungal biomolecules in metal ion reduction and surface stabilization, indicating effective bio-capping of the nanostructures. The biofunctional performance of the biosynthesized Ag-ZnNSs/Rs was evaluated through antioxidant and antimicrobial assays. Compared to the crude mushroom extract, the nanostructures exhibited significantly enhanced 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC₅₀ value of 7.29 ± 0.10 mg mL^-1 compared to 13.66 ± 0.15 mg mL^-1 for the crude extract. In addition, notable antimicrobial activity was observed against representative Gram-positive and Gram-negative bacteria (<i>Bacillus cereus</i>, <i>Bacillus subtilis</i>, <i>Staphylococcus aureus</i>, <i>Escherichia coli</i>, and <i>Pseudomonas aeruginosa</i>) as well as the yeast <i>Candida albicans</i>. Overall, this study demonstrates that <i>Russula sanguinea</i> is an effective biological platform for the green synthesis of silver-decorated zinc-based nanostructures with improved biofunctional properties, highlighting the potential of wild mushrooms as underexplored resources in sustainable nanomaterial development.