GREEN SYNTHESIS OF SILVER NANOPARTICLES AS AN ANTIBACTERIAL AGENT: OPTIMIZATION OF SYNTHESIS CONDITIONS WITH RESPONSE SURFACE METHODOLOGY

Abstract

In the present work, the synthesis of silver nanoparticles (AgNPs) through a green synthesis method using avocado (Persea americana) leaf as a biological reductant and capping agent. The synthesized AgNPs were characterized by zetasizer, FTIR, UV-vis spectrophotometer, XRD, and SEM. Besides, response surface methodology was used to understand and optimize the effect of the experimental parameters on the green synthesis of AgNPs. Three experimental parameters were chosen as independent variables: temperature, AgNO3 concentration, and aqueous leaf extract volume. A quadratic model was established as a functional relationship between three independent variables and the effective hydrodynamic diameter (nm) of AgNPs. The results of model fitting and statistical analysis demonstrated that only AgNO3 concentration was statistically significant parameter. The optimum conditions for minimum effective hydrodynamic diameter (nm) of AgNPs (32.74 nm) were temperature of 25 oC, AgNO3 concentration of 0.001 M, and aqueous leaf extract volume of 50 mL. Moreover, the antibacterial activities of AgNPs for S. typhimurium, E. coli O157:H7, S. aureus, and L. monocytogenes were tested and it was found that AgNPs had stronger inhibitory effects on growth of L. monocytogenes than the other bacteria.