Cashew Plant-Mediated Biosynthesis of Silver Nanoparticles and Evaluation of their Applications as Antimicrobial Additive for Consumer Care Products

Abstract

This study reports the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous extract
obtained from Anacardium occidentale stem bark and evaluation of their antibacterial activities as
well as their potential applications as antimicrobial additives for detergent and toothpaste. The
biosynthesized AgNPs were analyzed using UV–Vis spectroscopy, Fourier-transform infrared
spectroscopy (FTIR), and scanning electron microscopy (SEM). The particles were dark brown in
colour with maximum absorbance at wavelength 419 nm. They were mainly spherical in shape
with size ranges from 20 to 60 nm. The peaks of FTIR spectrum revealed that their formation was
facilitated by protein molecules present in the extract. The AgNPs exhibited strong antibacterial
property against pathogenic strains of Staphylococcus aureus, Escherichia coli and Pseudomonas
aeruginosa. Furthermore, the incorporation of the AgNPs into a locally-made liquid detergent and
toothpaste led to complete inhibition of bacterial and fungal contaminants such as S. aureus, E.
coli, P. aeruginosa, Aspergillus niger, and Aspergillus flavus. The results obtained herein therefore
suggest potential applications of the AgNPs in biomedical area and as antimicrobial additives in
the production of consumer care products like detergents and toothpastes. To the best of our
knowledge, this is the first reference to the use of biosynthesized AgNPs as antimicrobial additives
for detergents and toothpastes.

Keywords: Anacardium occidentale; Silver nanoparticles; Biosynthesis; Antimicrobial activity;
Antimicrobial additive.