▎ 摘　　要

To deal with the increasing consumption of metal oxide nanoparticles and carbon-based nanomaterials challenges, researchers have focused their attention on finding environmentally friendly paths for the synthesis of nanoparticles. In this study, a green approach synthesized graphene oxide-based nanoparticles from brown seaweed of Polycladia myrica, ZnO, and TiO2 nanoparticles. The nanoparticles were investigated with XRD, Raman, FESEM, EDS, mapping, and TEM. The bioactivity of antibacterial, anti-algae, and toxicity of barnacle larvae was evaluated for the nanoparticles. The best results were observed in the antibacterial test and toxicity of barnacle larvae in the graphene oxide reduced with P. myrica/zinc oxide (GZ) nanoparticles and anti-algae test in the graphene oxide reduced with P. myrica/zinc oxide/titanium dioxide (GTZ) nanoparticles. Compared with inorganic NPs, the nanoecotoxicological effects of GZ and GTZ nanoparticles are less studied in saltwater. However, the results presented in this study provide a better understanding of the antimicrobial, toxic potential, and benefits of green GZ and GTZ nanoparticles to replace them in an eco-friendly manner with a chemical counterpart for widespread biomedical applications.