Green synthesis, characterization and antimicrobial activity of gold and silver nanoparti̇cles

Metallic nanoparticles are particles between 1-100 nm in size and can be used in many applications. Several studies have been conducted to use these particles as antimicrobial and anticancer agents. It is possible to produce metallic nanoparticles by various methods. Chemical and physical methods are used extensively in the production of metallic nanoparticles. Due to the various disadvantages of chemical and physical methods, the production of metallic nanoparticle with biological method is a promising method. Biological methods are safe, inexpensive and environmentally friendly methods. Fungi, prokaryotes, plants, archaea, algae and enzymes can be used for metallic nanoparticle synthesis. In this study, filtrates and extracts of Bjerkandera adusta were used for the production of gold nanoparticle (AuNP) and silver nanoparticle (AgNP). Firstly, fungal filtrate and extracts were obtained and used in nanoparticle production. The first indicator of nanoparticle production was the color change and characteristic absorption band due to surface plasmon resonances of metallic nanoparticles. Then, nanoparticles were characterized and their antimicrobial properties were tested. While generally spherical AuNPs of 12-37 nm were obtained with B. adusta filtrates at pH 12, AuNPs with a mean size of 20 nm were obtained with B. adusta extract. AgNP production studies were performed with B. adusta filtrates and irregularly shaped and approximately 39 nm AgNPs were obtained. The results of this study showed that AgNPs were much less dispersive than AuNPs and were aggregated. The antimicrobial effects of metallic nanoparticles were evaluated by microdilution method based on determination of minimum inhibitory concentration (MIC). Gram positive Staphylococcus aureus ATCC 29213, gram negative Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 and yeasts Candida albicans ATCC 90028 and Candida tropicalis were used as test microorganisms. Nanoparticles showed low antimicrobial activity on test microorganisms, compared to the standard antibiotics used.