Bacteriagenic silver nanoparticles: synthesis, mechanism, and applications

Abstract

Silver nanoparticles (AgNPs) have received tremendous attention due to their significant antimicrobial properties. Large numbers of reports are available on the physical, chemical, and biological syntheses of colloidal AgNPs. Since there is a great need to develop ecofriendly and sustainable methods, biological systems like bacteria, fungi, and plants are being employed to synthesize these nanoparticles. The present review focuses specifically on bacteria-mediated synthesis of AgNPs, its mechanism, and applications. Bacterial synthesis of extra- and intracellular AgNPs has been reported using biomass, supernatant, cell-free extract, and derived components. The extracellular mode of synthesis is preferred over the intracellular mode owing to easy recovery of nanoparticles. Silver-resistant genes, c-type cytochromes, peptides, cellular enzymes like nitrate reductase, and reducing cofactors play significant roles in AgNP synthesis in bacteria. Organic materials released by bacteria act as natural capping and stabilizing agents for AgNPs, thereby preventing their aggregation and providing stability for a longer time. Regulation over reaction conditions has been suggested to control the morphology, dispersion, and yield of nanoparticles. Bacterial AgNPs have anticancer and antioxidant properties. Moreover, the antimicrobial activity of AgNPs in combination with antibiotics signifies their importance in combating the multidrug-resistant pathogenic microorganisms. Multiple microbicidal mechanisms exhibited by AgNPs, depending upon their size and shape, make them very promising as novel nanoantibiotics.

Effect of Incubation Time, CuSO4 and Glucose Concentrations on Biosynthesis of Copper Oxide (CuO) Nanoparticles with Rectangular Shape and Antibacterial Activity: Taguchi Method Approach

“…In the case of bacterial approach for biosynthesis of NPs, it can utilize culture supernatant [32,33], bacterial biomass [34], cell-free extract [35], and bacterial derived components [36]. Therefore, in this study, we used culture supernatant as the extracellular approach of biosynthesis CuO NPs due to the simple recovery of NPs compared to the intracellular mode [37].…”

Kinetics of Synthesis of Gold Nanoparticles by Acinetobacter sp. SW30 Isolated from Environment

“…In Verticillium sp. small uniform AuNP were obtained at 250 and 500 mg/l HAuCl 4 and at higher concentration (2500 mg/l) very large and irregular AuNP were synthesized [21]. In Coriolus versicolor, increased salt concentration, led to increase in rate of nanoparticle synthesis without affecting the morphology [22].…”

Improved Yield of Green Synthesized Crystalline Silver Nanoparticles With Potential Antioxidant Activity

“…The contamination from these toxic chemicals can be avoided by synthesizing SNPs using biological methods like microbes and plants. Many bacteria and fungi have been used for the biosynthesis of SNPs, but the process is relatively slow in comparison to plant extract [9][10][11][12][13][14][15] . Moreover, it is very difficult to maintain bacterial and fungal strains for long term use.…”