Antimicrobial Properties of AgNP/TEMPO-Oxidized Cellulose Nanofiber/Chitosan Composite Fibers

Abstract

This study successfully synthesized functionalized silver nanoparticle/TEMPO-oxidized cellulose nanofiber/chitosan (AgNP/TOCN/CS) composite fibers. First, the TOCN/CS composite fibers were prepared through the wet-spinning technique, yielding Ag/TOCN/CS composite fibers after immersion in a 5 mM AgNO3 aqueous solution for 3 h, followed by washing with 100 mL of deionized water five times. Second, upon heat treatment without adding other reducing agents, TOCN reduced the Ag+ in the Ag/TOCN/CS composite fibers to AgNP/TOCN/CS composite fibers on the surface of the CS fibers. The fiber color changed from white to yellow-orange when the temperature changed from 100 to 170 °C. In addition, the results suggest that the heat treatment at 130 °C for 20 min was the optimal heat treatment condition. Meanwhile, soaking the fibers in 50 mM ascorbic acid for 1 min is the best condition for ascorbic acid reduction. The antibacterial test results showed that the AgNP/TOCN/CS composite fibers formed via ascorbic acid reduction exhibited better antibacterial activity against both Escherichia coli and Bacillus subtilis than those produced via heat treatment. In summary, AgNPs formed on the fiber surface of AgNP/TOCN/CS composite fibers and showed antibacterial activity, confirming the successful addition of antibacterial properties to TOCN/CS composite fibers.