Synthesis of alga-coated copper oxide nanoparticles with potential applications in shrimp farming

Copper (Cu) is a crucial element that plays a vital role in facilitating proper biological activities in living organisms. In this study, copper oxide nanoparticles (CuO NPs) were synthesized using a straightforward precipitation chemical method from a copper nitrate precursor at a temperature of 85 °C. Subsequently, these NPs were coated with the aqueous extract of Sargassum angustifolium algae. The size, morphology, and coating of the NPs were analyzed through various methods, revealing dimensions of approximately 50 nm, a multidimensional shaped structure, and successful algae coating. The antibacterial activity of both coated and uncoated CuO NPs against Vibrio harveyi, a significant pathogen in Litopenaeus vannamei, was investigated. Results indicated that the minimum inhibitory concentration (MIC) for uncoated CuO NPs was 1000 μg/mL, whereas for coated CuO NPs, it was 500 μg/mL. Moreover, the antioxidant activity of the synthesized NPs was assessed. Interestingly, uncoated CuO NPs exhibited superior antioxidant activity (IC50 ≥ 16 μg/mL). The study also explored the cytotoxicity of different concentrations (10-100 μg/mL) of both coated and uncoated CuO NPs. Following 48 h of incubation, cell viability assays on shrimp hemocytes and human lymphocytes were conducted. The findings indicated that CuO NPs coated with alga extract at a concentration of 10 μg/mL increased shrimp hemocyte viability. In contrast, uncoated CuO NPs at a concentration of 25 μg/mL and higher, as well as CuO NPs at a concentration of 50 μg/mL and higher, led to a decrease in shrimp hemocyte survival. Notably, this study represents the first quantitative assessment of the toxicity of CuO NPs on shrimp cells, allowing for a comparative analysis with human cells.