Synthesis of Melanin Mediated Silver Nanoparticles from Aeromonas sp. SNS Using Response Surface Methodology: Characterization with the Biomedical Applications and Photocatalytic Degradation of Brilliant Green

Abstract

Melanin is ubiquitous in nature and has wide applications in cosmetics, agriculture, and medicine. The synthesized melanin from bacterium Aeromonas sp. SNS was further used as capping and reducing agents for synthesis of silver nanoparticles (AgNPs). The influence of the experimental parameters (AgNO3, melanin concentrations, and temperature) and their interactions on the nanoparticle synthesis was optimized using response surface methodology (RSM). The Central Composite Design (CCD) with three independent variables was optimized for the effective synthesis of AgNPs. The optimized synthesis of AgNPs was achieved at the shortest time of 14.12 h in the presence of 2.62 mM AgNO3, and 32.30 µg ml−1 melanin concentration at 54.86 °C temperature. The synthesized AgNPs were characterized by means of UV–visible spectroscopy, FTIR, SEM, TEM, and PSD respectively. The AgNPs exhibited excellent antimicrobial activity against human and food-related pathogens. These AgNPs also have strong antioxidant potential which was estimated by DPPH, DMPD and FRAP radical scavenging assays. The 92.62% photocatalytic degradation of 250 PPM brilliant green was observed in 120 min. The present finding accelerates the melanin associated AgNPs could be used in the cosmetic and pharmaceutical industries as well as in textile industries as they have superior antimicrobial, antioxidant, and photocatalytic activity.