Comparative nanotoxicity of polyethylene, silver, and copper oxide nanoparticles in African catfish (Clarias gariepinus): impacts on antioxidant defense, immunity, and tissue integrity

The rapid expansion of nanotechnology has increased nanoparticle release into aquatic systems, raising ecological safety concerns. This study compares the toxicological impacts of polyethylene (PE-NPs), silver (Ag-NPs), and copper oxide nanoparticles (CuO-NPs) on Clarias gariepinus , focusing on nano-specific biological effects. Transmission electron microscopy characterized PE-NPs as irregularly shaped with a 40.4 nm average diameter, Ag-NPs as spherical (95 nm), and CuO-NPs as semi-spherical (63.4 nm). Catfish were exposed to 100 mg/L of each NP type over 15 days, revealing significant reductions (p < 0.0001) in antioxidant enzymes glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (TAC). Immunological parameters, including lysozyme (LYZ) activity, immunoglobulin M (IgM), and phagocytic activity (PA), were also significantly reduced (p < 0.0001), indicating immune suppression. Histopathological analysis revealed pronounced tissue-specific damage: PE-NPs caused dilated blood sinusoids in liver cells; Ag-NPs led to necrosis and hydropic degeneration; CuO-NPs resulted in melanomacrophage centers and increased mitotic activity. In kidney tissues, PE-NPs caused vacuolation, Ag-NPs induced degeneration and hemorrhages, and CuO-NPs displaced epithelial linings. Collectively, these findings demonstrate that exposure to these nanoparticles induces significant biochemical and histological disturbances in Clarias gariepinus , emphasizing the need for nano-specific risk assessments in aquatic environments.