Sonochemically synthesized CuO-NPs: individual and synergistic toxicity assessment with sodium arsenite in adult zebrafish

Abstract

Sodium arsenite (NaAsO₂) and sonochemically synthesized copper oxide nanoparticles (CuO-NPs) pose escalating risks to aquatic animals due to their bio-accumulative potential, persistence, and interaction; when co-occurring, their combined effects represent a new class of emerging contaminants (ECs) with heightened ecological relevance. We synthesized CuO-NPs and characterized them using powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy and UV-visible spectroscopy. Zebrafish (Danio rerio) were exposed to NaAsO₂, CuO-NPs, and their combination for 28 days, and they were subjected to comprehensive histopathological analysis of muscle tissues and biochemical and genotoxic examinations on the 7th, 14th, 21st, and 28th days of exposure. The synthesized CuO-NPs exhibited an average crystallite size of 10.56 nm, with a monoclinic crystalline structure and spherical morphology. Treatment with CuO-NPs and their co-exposure with NaAsO₂ induced histomorphological alterations in muscle tissues, significantly elevated hepatic oxidative stress biomarkers (P ≤ 0.0001), and suppressed total protein (P ≤ 0.05), antioxidant (P ≤ 0.0001), and acetylcholinesterase (P ≤ 0.0001) enzyme activities. The imbalance of oxidants and antioxidants induced DNA damage, as revealed by the comet assay. The correlational analysis exhibited a strong, significant correlation (P = 0.05) among oxidative stress biomarkers, antioxidant enzyme activities, and DNA damage. These findings indicate that CuO-NPs exhibit individual and synergistic toxicity with NaAsO₂, highlighting their potential ecological concerns.