Green synthesis of silver nanoparticles using Pyrus betulifolia Bunge and their antibacterial and antioxidant activity

Abstract

Biosynthesized silver nanoparticles have attracted enormous interest due to the unique features of biosynthesis such as simplicity, cost-effectiveness, and free of organic solvents. Plant extracts are of great potential in the biosynthesis of metal nanoparticles due to their abundant availability, reducing activity and stabilizing ability. Here, the biosynthesis of AgNPs was accomplished at room temperature within 60 min with the extracts of Pyrus betulifolia Bunge branches, in which plant bioactives like phenols, proteins, and sugars acted as the reducing and capping agents for the AgNPs. The as-synthesized AgNPs were extensively characterized using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and Zetasizer. The maximum absorbance of UV–vis spectra appeared at 425 nm, a characteristic peak for AgNPs, indicating the successful formation of the nanoparticles. Further investigation with TEM showed that the as-synthesized AgNPs were uniform and spherical particles with an average size around 19.9 nm with the zeta potential of −18 mV. FTIR spectroscopy confirmed that various functional groups were responsible for reducing and stabilizing during the biosynthesis process. In addition, the antimicrobial activities of the as-synthesized AgNPs, determined with the agar diffusion method, demonstrated that the AgNPs were extremely effective against both bacteria and fungi. Furthermore, the as-prepared AgNPs showed excellent antioxidant activities with IC50 values of 14.3 μg/mL measured by detecting the scavenging ability of DPPH. The results from MTT and hemolysis assay also indicated that the prepared AgNPs are highly biocompatible, enabling such green synthesized AgNPs applicable in various areas.