Title: Cellular mechanisms of cadmium-induced toxicity and interaction with organic and inorganic nanoparticles

Abstract

Among emerging pollutants, potential effects coming from their contemporary presence with nanoparticles (NPs) in the environmentare of great concern. The co-existence of NPs of classical and emerging pollutants into the aquatic system potentially modifies their interaction with the biota. Within classical pollutants, Cd and Cd-compounds have been classified as human carcinogens by the International Agency for Research on Cancer (IARC), representing an environmental problem that also involves human health. Among cellular cadmium effects, the most important seem to be cadmium interaction with DNA repair mechanisms, generation of reactive oxygen species and induction of apoptosis. The present study aimed to investigateif cellular mechanisms of cadmium-induced toxicity resulted affected by the interaction between organic and inorganic nanoparticles. Cellular responses were investigated in cadmium-contaminated marine waters after exposure of both organic and inorganic NPs: two forms of commercial nano-TitO2 and carbon black (CB)-derived hydrophilic NPs. Portions of the marine mussel Mytilusgalloprovincialis gill tissue were exposed to CdCl2 in presence of selected NPs to simulate the interactions between cells and xenobiotics. DNA primary damage was evaluated by the alkaline version of Comet assay; chromosomal damage and cell proliferation were assessed by Cytome assay; apoptosis was evaluated by Diffusion assay. Moreover, TEM in cell was planned to check the actual internalization of NPs, in order to verify that the potential genotoxic effects induced by NPs were paralleled by their cellular uptake. An induction of apoptosis in gill cells from CdCl2 treated biopsies was observed while the level of apoptotic cells exerted by CdCl2 was recovered to the control level in gill biopsies co-treated with CdCl2 and NPs (both organic and inorganic). In terms of DNA primary damage the selected NPs did not exert genotoxicity when tested alone, and only the inorganic ones were able to reduce the DNA damage level exerted by cadmium treatment even though not to the control level. These results provided informations for the innovative remediation approaches aimed to promote the use of nanoparticles (NPs) to clean metal-contaminated waters for human and environmental health protection.