SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL ACTIVITY OF EXTRACTED CHITOSAN-BASED SILVER NANOPARTICLES

Abstract

In recent years, nanoparticles of noble metals such as silver have gained enormous attraction owing to their distinct physical, chemical, and biological properties. In the present study, silver nanoparticles (AgNPs) were synthesized from silver nitrate (AgNO₃) using extracted chitosan as the reducing agent. The chitosan was extracted from the exoskeleton of the marine crab Portunus pelagicus. Three different sample solutions were prepared using 0.02mM AgNO3 in 0.5% (w/v) chitosan, 0.04 mM AgNO3 in 0.5% (w/v) chitosan, 0.06 mM AgNO3 in 0.5% (w/v) chitosan. Preliminary characterization of the formed silver nanoparticles was made based on the measurements of ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). The characteristic absorbance peak corresponding to silver nanoparticles was observed at 400nm. The average size of chitosan-based silver nanoparticles was in the range of 160-530nm. The synthesized nanoparticles were further tested for their antimicrobial activity. The synthesized chitosan-based silver nanoparticles exhibited effective antibacterial activity against Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli as well as Gram-positive bacteria Bacillus subtilis, Staphylococcus aureus, and antifungal activity against Candida albicans, Aspergillus flavus, Penicillium chrysogenum. Among the different concentrations of silver nitrate solutions, a maximum zone of inhibition against all the microbial cultures was observed with chitosan-based silver nanoparticles produced using 0.06mM silver nitrate solution. The synthesized nanoparticles were further incorporated in Cotton Gauze to evaluate its antibacterial activity. It showed higher bactericidal activity against Pseudomonas aeruginosa followed by Bacillus subtilis, Staphylococcus aureus, and Escherichia coli and thus proved to have the potential to be used as wound dressing material.