Carbon-Coated Cu ₂ O Nanoparticles with Multifunctional Aquatic Bioactivity via Tunable Copper-Ion Release

Rapid algal proliferation poses a persistent threat to water quality and aquatic biodiversity, demanding defined, ecofriendly intervention approaches. To address this challenge, sustainable carbon-coated cuprous oxide nanoparticles (C@Cu 2 O NPs) were engineered as a surface-modified framework to control copper-ion release and nanobio interactions in a simplified aquatic ecosystem. A starch-derived carbon layer stabilized the nanoparticles and allowed controlled, time-dependent copper-ion delivery, mitigating acute toxicity. The antialgal efficacy was revealed using Chlorella vulgaris, achieving 90% inhibition at 0.12 mg/L over 12 days. Simultaneously, ducL emna ) was used for phytoextraction, gradually absorbing released copper ions and reducing aqueous concentrations; at 0.09 mg/L, water copper levels decreased to 12.55 μg/L, while plant tissue reached 1.084 μg/g by day 12. Significantly, C@Cu 2 O NPs inhibited algae without compromising duckweed growth and fish. In a mixed aquatic environment, the interaction between duckweed and fish facilitated the controlled availability of copper, leading to algal inhibition and clearer water. This study highlights a rational, mechanism-driven nanotechnology platform that incorporates controlled copper delivery with multifunctional aquatic ecosystem restoration.