Copper bionanocomposite mitigates arsenic toxicity in Oreochromis niloticus

Background Arsenic (As) is an extremely hazardous trace metalloid frequently found in water bodies, where it poses substantial threats to all living organisms, including fish. Its removal has therefore become a significant global challenge. Methods We explored the adsorptive capacity of a copper 1,4-benzenedicarboxylate metal-organic framework supported on rice husk-derived activated carbon (Cu-BDC@AC) nanocomposite toward As toxicity in Oreochromis niloticus. Fish were exposed to As (5 mg/L), the nanocomposite (NP, 1 mg/L), or both (As + NP) via water for 3 weeks. Serum biochemical parameters; antioxidant, pro-inflammatory, and apoptotic gene expression; hepatic and renal histopathology; and hepatic As bioaccumulation were assessed. Results Fish exposed to As exhibited significantly higher ALT and AST activities, accompanied by pronounced oxidative stress with elevated MDA and NO levels, and depleted CAT activity and GSH concentration. Nrf-2, SOD, and CAT were significantly downregulated. It also induced inflammatory and apoptotic responses, indicated by upregulated TNF-α, IL-1β, IL-6, IL-21, IFN-γ, and caspase-3, with downregulated Bcl2 expression relative to controls. Histopathology revealed extensive hepatic and renal lesions in the As group, whereas the NP-only group showed no adverse alterations relative to controls. Conclusions Cu-BDC@AC significantly attenuated oxidative, inflammatory, and apoptotic stresses and reduced hepatic As accumulation relative to the As-intoxicated group. These findings suggest that Cu-BDC@AC can mitigate As-induced toxicity in Nile tilapia and warrant further study as a candidate bio-adsorptive material for aquaculture water treatment.