Synthesis of Ag@Fe2O3 nanocomposite based on O-carboxymethylchitosan with antimicrobial activity

Abstract In this paper, nano-hybrid particles of Ag@Fe 2 O 3 based on O -carboxymethylchitosan were successfully synthesized using different reducing agents (NaBH 4 , sucrose) and without reducing agent. The smallest silver nanoparticles were those prepared without reducing agent (∼5 ± 3 nm). The average size of silver particles prepared with NaBH 4 is around 5–15 nm, and for samples prepared with sucrose, the average particle size is 10–25 nm. The magnetization curves are roughly reversible, indicating that γ-Fe 2 O 3 nanoparticles transit to a superparamagnetic state. Nanocomposites subjected to antimicrobial tests showed great antimicrobial activity against gram-positive ( Staphylococcus aureus ) and gram-negative ( Escherichia coli ) bacteria, and good activity against the yeast Candida albicans and resistant strains of Staphylococcus aureus . The antibacterial behavior as a function of time was investigated in microbial growth kinetics, and the best nanocomposite was the one without reducing agent, which completely inhibited microbial growth for 48 h.