Enhanced antimicrobial activity of silver nanoparticles with controlled particle size by pH variation

Abstract

PVA capped spherical silver nanoparticles (AgNPs) were synthesized at various pH conditions of reaction solution by chemical reduction method. Tuning of reaction solution pH in a narrow range could have a profound effect on particle size. The synthesized AgNPs have been characterized by studying their structural, morphological, optical and antimicrobial properties. Crystallite size decrement with the increase of pH was confirmed by X-ray diffraction analysis. UV-vis spectra showed single surface plasmon resonance (SPR) peak at similar to 420 nm and a blue shift in SPR was elicited with increment of pH. AgNPs were found to be photoluminescent and enhancement in photoluminescence intensity was observed with the increase in the reaction solution of pH. Fourier transform infrared spectroscopy (FTIR) measurements indicated that the nanoparticles were capped by PVA. The synthesized AgNPs displayed potent antimicrobial activity against Escherichia coli, Pseudomonas sp., Aspergillus niger and Penicillium sp. with particle size decrement.