Mechanism of action and toxicological evaluation of engineered layered double hydroxide nanomaterials in Biomphalaria alexandrina snails

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 nontarget aquatic invertebrate increasing. So, the present study aimed to synthesize and confirm the crystalline formation of Co-Cd-Fe LDHs and Co-Cd-Fe/PbI2 (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/PbI2 LDH has more toxic effect to adult Biomphalaria than Co-Cd-Fe LDHs (LC50 was 56.4 and 147.7 mg/L, 72 h of exposure, respectively). The effect of LC25 (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 sublethal concentration caused abnormalities in hemocyte shapes and upregulated IL-2 level in soft tissue. In addition, it decreased levels of nonenzymatic reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), caspase-3 activity, and total protein content in significant manner. Glutathione S-transferase (GST) activity was not affected by LDH exposure. It caused histopathological damages in both glands of snails and also caused a genotoxic effect in their cells. 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.

Automated summary

The study found that Co-Cd-Fe/PbI2 LDH had a greater toxic effect on adult freshwater snails compared to Co-Cd-Fe LDHs, while exposure to Co-Cd-Fe LDHs resulted in suppressed embryonic development. LDH exposure also led to alterations in cell structures and gene expression in the snails.