Novel method for biosynthesis of silver nanoparticles using melanin and its application on wool to impart antimicrobial activity

Abstract

A novel method for biosynthesis of silver nanoparticles using a polyphenolic pigment (melanin) has been proposed to impart antimicrobial properties to wool fabric. A diphenolic catechol has been combined with potato juice to produce melanin, which is used as a simultaneous reducing and dispersing agent for the synthesis of silver nanoparticles. The process variables used for the synthesis of melanin have been optimized to produce melanin with maximum reduction potential. The synthesized silver nanoparticles are then characterized and quantified. The optimum conditions used for the synthesis of melanin are found to be 0.1% catechol, 25% potato juice, 6.5 pH, 95˚C temperature and 45 min treatment time. Spherical shaped silver nanoparticles with average sizes of 35 nm and 50 nm are obtained and then applied on wool fabrics by exhaustion method to observe antimicrobial effect. It is observed that the treated wool has excellent antimicrobial activity against both the Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria.