Preparation and characterization of cellulose nanocrystal coated with silver nanoparticles with antimicrobial activity by enzyme method

Silver nanoparticles (AgNPs) exhibit broad-spectrum antibacterial activity and serve as effective antimicrobial agents against antibiotic-resistant bacteria. In this study, agricultural waste corn straw was used as the raw material to obtain cellulose nanocrystal (CNC) through enzymatic hydrolysis. The hydrolysate was employed as reducing agents to synthesize CNC-AgNPs. The inhibition effect of CNC-AgNPs on pathogenic microorganisms was analyzed to explore the optimal preparation conditions and antimicrobial mechanisms. XRD, FTIR, and TEM analyses confirmed the presence of silver nanoparticles, with a more uniform particle size of nanoparticles under alkaline conditions. XRD and TGA results showed that silver loading improved the thermal stability of CNC, particularly under pH 11 conditions. pH 4.8-CNC-AgNPs exhibited a sustained antibacterial effect for over 264 h against Escherichia coli and a 96-hour inhibition against Staphylococcus aureus, as well as significant inhibitory effects on the bacterial community in shoe insoles. CNC-AgNPs can be used as additives in composites or as coatings for the composites.