Green Synthesis of Caulerpa chemnitzia–Derived Silver Nanoparticles for Breast Cancer Therapy: Current Advances, Mechanisms, and Future Perspectives

Abstract Breast cancer remains the most frequently diagnosed malignancy among women worldwide and a leading cause of cancer-related death, prompting sustained interest in therapeutic strategies that combine efficacy with reduced systemic toxicity. Green nanotechnology, in which biological extracts replace hazardous chemical reagents as reducing and capping agents during nanoparticle fabrication, has emerged as an environmentally benign route to biologically active nanomaterials. Marine macroalgae of the genus Caulerpa are of particular interest because their tissues are naturally rich in polyphenols, sulfated polysaccharides, pigments, and distinctive alkaloids such as caulerpin, all of which can serve simultaneously as reducing and stabilizing agents during the biosynthesis of silver nanoparticles (AgNPs). This review synthesizes the published evidence on green synthesis of AgNPs from Caulerpa species, including Caulerpa chemnitzia, C. racemosa, C. serrulata, C. scalpelliformis, and C. lentillifera, with an emphasis on synthesis optimization, physicochemical characterization, and the cellular mechanisms by which such nanoparticles exert cytotoxic and pro-apoptotic effects on breast cancer cell lines, principally MCF-7. Reactive-oxygen-species generation, mitochondrial membrane depolarization, caspase-3/9 activation, and modulation of Bax/Bcl-2 expression recur as the dominant mechanistic themes across the literature reviewed. The review further situates Caulerpa-derived AgNPs within the broader landscape of algae- and plant-mediated nanoparticle synthesis, addresses toxicological and biocompatibility considerations, and outlines current gaps — most notably the scarcity of dedicated breast-cancer bioassays for C. chemnitzia-derived AgNPs specifically — together with priorities for future in vivo and translational research.