Aquatic environmental risk assessment of chitosan/silver, copper and carbon nanotube nanocomposites as antimicrobial agents.

Despite the potential antimicrobial and water purification benefits of chitosan-based nanocomposites, there are growing concerns regarding the hazards of leached nanoparticles (NPs) to the in-contact circumference. The antibacterial performance of the nanocomposites of chitosan with silver and copper NPs and carbon nanotubes was assessed with an emphasis on their impact on fish health. The minimal inhibitory concentrations of each preparation and the growth curves of Aeromonas hydrophila exposed to different nanocomposites were measured. Five groups of Oreochromis niloticus were exposed to chitosan nanocomposites for three weeks. A combination of a low concentration of the NPs in the chitosan matrix improved their antimicrobial properties. However, aqueous exposure to these materials still had hazardous effects on fish health. Experimental groups of O. niloticus exposed to these nanocomposites exhibited oxidative stress, tissue DNA fragmentation and higher expression of pro-inflammatory and immune-related genes such as TNF-α and IL1β. Various pathological tissue alterations were observed in gills, liver, spleen and intestine. Exposure to some of the prepared nanocomposites led to significant DNA damage in hepatic cells with a marked increase in the apoptotic index.