Hybrid CuO-Al₂O₃-ZnO nanoparticles synthesized via a green route for advanced polyurethane-based marine antifouling...

This investigation presents an original and environmentally sustainable approach for inhibiting marine biofouling using ecologically synthesized CuO-Al₂O₃-ZnO hybrid nanoparticles embedded in a polyurethane matrix. Copper oxide (CuO) nanoparticles were biosynthesized utilizing Padina sp. extract, zinc oxide (ZnO) was extracted of Avicennia marina, and aluminum oxide (Al₂O₃) was utilized as a formulation using Sargassum sp. extract, all of which served as natural reducing and stabilization agents. To confirm uniformity as well as the formation of the hybrid, structural characterization studies (FTIR, XRD, FESEM, EDS, AFM) indicated uniform dispersion of the nanoparticles and formation of the hybrid. Efficacy studies for the nanoparticles were performed with antibacterial and antialgal tests, and tests on the lethal effects of the nanoparticles were conducted on two organisms, Amphibalanus amphitrite and Artemia salina, in the laboratory. Our study indicates that CuO demonstrated the greatest and fastest antibacterial activity (MIC = 12.5 μg/mL). CuO and ZnO nanoparticles inhibited the growth of Isochrysis galbana by 98% and 82% respectively, while Al₂O₃ only inhibited growth by 13%, and the CuO-ZnO-Al₂O₃ hybrid achieved a stable inhibition of 75%. The order of toxicity in both Artemia salina and Amphibalanus amphitrite was CuO > ZnO > Hybrid > Al₂O₃. In field immersion studies, the hybrid nanoparticle coating inhibited biofouling by 84% compared to the control after three months of marine immersion. The findings present potential to utilize eco-synthesized hybrid nanostructures as adjuncts in biofouling management.