Toxicological evaluation of engineered layered double hydroxide nanomaterials to Biomphalaria alexandrina snails: a study on the mechanism of action

Layered double hydroxide (LDH) nanomaterials have recently become immense research area as it is used widely in industries. So, it's chance of their release into natural environment and risk assessment to non-target aquatic invertebrate increasing. So, the present study aimed to synthesize and confirme the crystalline formation of Co-Cd-Fe LDHs and Co-Cd-Fe /PbI 2 (LDH), and then to investigate the toxic impact of the two LDH on the adult freshwater snails ( Biomphalaia alexandrina ). Results showed that Co-Cd-Fe /PbI 2 LDH has more toxic effect to adult Biomphalaria than Co-Cd-Fe LDHs (LC 50 was 56.4 mg/l, 72 h of exposure). The effect of LC 25 (117.1 mg/l) of Co-Cd-Fe LDHs exposure on the embryo; showed suppression of embryonic development and induced embryo malformation. Also, it showed alterations in the tegmental architectures of the mantle-foot region of B. alexandrina snails as declared in scanning electron micrograph. Also, exposure to this sub lethal concentration caused abnormalities in hemocyte shapes and up-regulated IL-2 level in soft tissue. In addition, it decreased levels of non-enzymatic reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), caspase-3 activity and total protein content in significant manner. While, glutathione S-transferase (GST) activity was not affected by LDH exposure. It caused histopathological damages in both the hermaphrodite and digestive glands. Also, it has a genotoxic effect that was confirmed by alkaline comet assay. The results from the present study indicated that LDH has risk assessment on aquatic B. alexandrina snails and that it can be used as a biological indicator of water pollution with LDH