Toxicity of silver nanoparticle-incorporated bacterial nanocellulose to human cells and intestinal bacteria

Abstract

Bacterial nanocellulose (BNC) has a big potential for being used as a food packaging material and loading medium because of its outstanding mechanical properties and large surface area. To further increase its functionality, antimicrobial agents have been incorporated into BNC. The toxicity of AgNP/BNC slurry on intestinal bacteria and two types of human cells (human fetal cells and Caco-2 cells) was studied to evaluate the potential application of a AgNP/BNC film in food packaging materials. To obtain the AgNP/BNC slurry, BNC was synthesized by Gluconobacter xylinus, and AgNPs were incorporated in the BNC by a chemical reduction and an ultraviolet (UV) method. The slurry did not exhibit cytotoxic effects on Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus acidophilus, Bifidobacterium animalis and Escherichia coli, all of which represent human intestinal bacteria. The AgNP/BNC slurry decreased cell viability only when its concentration was higher than 2000 μg/mL. Damage to the treated bacterial and human cells was studied by transmission electron microscopy. A complete and normal cell structure and undamaged mitochondria demonstrated that both intestinal bacteria and human cells were not detrimentally affected by the AgNPs/BNC slurry. Based on the results of this study, we conclude that the AgNP/BNC slurry could be considered as a safe and promising antimicrobial packaging material.