Antibacterial Effectiveness of Rice Water (Starch)-Capped Silver Nanoparticles Fabricated Rapidly in the Presence of Sunlight.

Abstract

Green synthesized silver nanoparticles (AgNPs) have enormous applications. Hence, there is an increasing demand to explore diverse bioresources for AgNP fabrication to make the process more cost-effective and rapid as possible. Due to the abundantly present hydroxyl groups of rice starch, it provides ideal sites for metal ion complexation and thereby synthesis of nanoparticles with promising activity. So the study was designed to develop rapid, eco-friendly and cost-effective method for green AgNP synthesis using boiled rice water starch in the presence of sunlight irradiation. The starch-capped nanoparticles (sAgNPs) formed in the study were found to have the surface plasmon absorbance at 439 nm. The study showed optimum yield of sAgNPs when 25% rice starch was treated with aqueous 1 mM AgNO3 for 15 min in the presence of sunlight. Fourier transform infrared spectroscopy analysis provided mechanistic insight into the role of -OH groups of starch in the reduction of AgNO3 to sAgNPs. On further characterization by X-ray diffraction analysis, the sAgNPs were identified to have FCC crystal structure. At the same time, high-resolution transmission electron microscopic analysis showed majority of sAgNPs to have spherical morphology, and dynamic light scattering study revealed the average particle size as 36.3 nm. Further confirmation on presence of AgNPs was carried out by energy-dispersive X-ray spectroscopy. Moreover, the sAgNPs exhibited promising antibacterial activity against foodborne pathogens, Salmonella Typhimurium and Staphylococcus aureus.