Plant extract-assisted biosynthesis of zinc oxide nanoparticles and their antibacterial application

Abstract

Abstract ZnO nanoparticles are multi-purposes materials that can be synthesized by several methods, including physical and chemical routes. A novel synthesis method of ZnO nanoparticles is the biological method using plant extracts as reducing and capping agents, such as the fruit extract of Averrhoa bilimbi. Plant extracts are superior agents for synthesizing nanoparticles because it provides essential phytochemical substances as reductor, capping agents, and free from toxicants. In this study, the effects of precursor concentrations and the amount of plant extract on the formation and morphology of nanoparticles were investigated. The characteristics of ZnO particles were studied by UV-Vis spectroscopy, XRD, FTIR, TEM, and DLS. The study showed that the formation of ZnO nanoparticles occurred after five hours reaction at 70°C, as indicated by color change of the solution. ZnO nanoparticle formation was confirmed by the maximum absorption at the wavelength of 372 nm and XRD analysis. FTIR analysis showed that the as-synthesized ZnO contained significant organic compounds on its surface, especially compared to commercial ZnO. Reduction reactions using A.bilimbi produce nanoparticles in the size from 35.4 to 59.5 nm with round shape and some agglomeration that were observed by TEM. The ZnO antibacterial property was tested against planktonic and biofilm Escherichia coli. The result showed that as-synthesized ZnO have comparable antibacterial antibiofilm property as the commercial ZnO nanoparticles at low concentration. Interestingly, this property was diminished when as-synthesized ZnO nanoparticles were used at high concentrations.