Antimicrobial effect and toxicity of cellulose nanofibril/silver nanoparticle nanocomposites prepared by an ultraviolet irradiation method

Abstract

The objective of this study was to synthesize a novel antimicrobial cellulose nanofibril/silver nanoparticle (CNF/AgNP) nanocomposite by an ultraviolet (UV) irradiation method and evaluate the toxicity of the nanocomposite to human colon cells. AgNPs coated on CNFs have an average size of ˜28 nm and exhibited a surface plasma resonance absorption peak at 402 nm. Coating AgNPs on CNFs interfered with the formation of intra-chain and inter-chain hydrogen bonds of cellulose. Moreover, the CNF/AgNP nanocomposite exhibited significant antimicrobial activities against two important food-borne pathogens, including Escherichia coli O157:H7 and Staphylococcus aureus. No apparent toxicity of the CNF/AgNP nanocomposite to Caco-2 and FHC human colon cells was observed, except when a high content of (≥500 μg/m L) of the nanocomposite was used for which a significant decrease of cell viability was observed. The nanocomposite’s toxicity was related to the content, size, and surface charge of UV-synthesized AgNPs on CNFs. These results indicate that the antimicrobial CNF/AgNP nanocomposite prepared by UV irradiation method can be potentially used as an active filler applied in food packaging materials.