Toxicology study of nanoclays adsorbed with the antimicrobial peptide nisin on Caenorhabditis elegans

Halloysite and montmorillonite nanoclays have a wide range of industrial and medical applications, including food packaging. To ensure safe incorporation of these clays into nanocomposites, toxicological screening must be performed. In this study, the acute toxicity of three nanoclays, namely halloysite, bentonite and montmorillonite modified with octadecylamine (Mt-ODA), was evaluated using the free-living nematode Caenorhabditis elegans as in vivo model. Nanoclays were tested pure and adsorbed with nisin, an important antimicrobial peptide used as food preservative. Lethal concentration 50% (LC50), nematode development, reactive oxygen species (ROS) production, quantification of catalase (CAT) and superoxide dismutase (SOD) enzymes, and lipid peroxidation were the toxicological endpoints evaluated in C elegans. Halloysite and Mt-ODA had the lowest and highest LD50, respectively. The adsoption of nisin on halloysite and bentonite provoked an increase in surviving nematodes. All treatments altered the normal growth, in different degrees, being nematodes exposed to bentonite the most affected. ROS production increased in all treatments, especially Mt-ODA, where lipid peroxidation was enhanced, suggesting high oxidative stress.