Biosynthesis of Silver and Gold Nanoparticles using Inonotus obliquus: A strategy for Antimicrobial, Antioxidant and
Sayed M S Abo El-Souad1, Marwa Sharaky2, Marwa A Ramadan3
1Department of Botany and Microbiology, Faculty of Science, Cairo University, Giza, 12613, Egypt. msayed@sci.cu.edu.eg.
Abstract:
The development of safer and greener routes to bioactive metal nanomaterials remains an active area of research. In this study, we report the one-pot synthesis of gold (Au@Chaga) and silver (Ag@Chaga) nanoparticles using the ethyl acetate fraction of Inonotus obliquus (Chaga) as a dual reductant and capping agent. The nanoparticles, characterized by TEM, showed uniform sizes of 26 ± 3 nm (Au@Chaga) and 12 ± 3 nm (Ag@Chaga). Ag@Chaga NPs showed a larger inhibition zone against Staphylococcus aureus (25 ± 3.0 mm), followed by Salmonella typhimurium (18 ± 1 mm) with MICs of 12.5 to 25 µg/mL. Au@Chaga yielded inhibition-zone diameters ranging from 12.7 ± 0.58 to 17.67 ± 2.08 mm, with MICs of 12.5 to 25 µg/mL. Anticancer activity was evaluated across 18 human cancer cell lines using SRB/MTT assays. Preliminary biocompatibility was assessed by parallel viability testing in non-tumorigenic human cells, including olfactory epithelial cells (OEC) and human skin fibroblasts (HSF). Au@Chaga generally showed broader antiproliferative activity than Ag@Chaga across several cancer cell lines, although responses varied among cancer and non-malignant cells. These findings highlight the need for formal calculation of the selectivity index and an extended biosafety assessment. The nanoparticles exhibited differential cytotoxic responses between cancerous and non-cancerous cells, highlighting the need for future studies to establish formal selectivity indices. Genotoxicity (Comet assay), oxidative and nitrosative stress markers, and antioxidant enzyme activities collectively suggest that redox perturbation contributes to the observed cellular responses. Overall, this study provides proof of concept that Chaga-mediated Au/Ag nanoparticles can be produced via a biogenic protocol and exhibit measurable in vitro antibacterial and anticancer activities within the stated scope. Extension to multidrug-resistant clinical isolates and quantitative selectivity analyses will be required to substantiate translational claims.
