Multifunctional Biogenic Copper Oxide Nanoparticles: A Comprehensive Review on Biomedical Applications, Photocatalytic Wastewater Treatment, and Future Perspective

Abstract In a world facing major challenges like climate change, environmental degradation, and public health, finding sustainable solutions through the development of nanoparticles has emerged as a critical area of innovation. This review presents a comprehensive summary of the biogenic synthesis of copper oxide nanoparticles (CuO‐NPs) using natural, eco‐friendly methods, particularly plant extracts. This green approach avoids harsh chemicals and reduces high energy consumption, relying instead on natural compounds in plants. Phytochemicals such as flavonoids, alkaloids, terpenoids, and phenolics act as natural reducing and stabilizing agents in this biosynthetic process, offering an eco‐friendly alternative to conventional methods. In the biomedical domain, their tunable band gap and surface chemistry render CuO‐NPs highly promising for photothermal therapy, targeted drug delivery, as well as exhibiting potent anticancer and antimicrobial activities. Beyond health, CuO‐NPs are effective in energy storage, photovoltaic systems, dye degradation with high photocatalytic efficiencies, and wastewater treatment, addressing critical environmental concerns. Despite their potential, several challenges must be addressed to ensure the safe and effective use of CuO‐NPs. These include optimizing synthesis protocols, standardizing characterization techniques, and evaluating toxicity and biocompatibility. Addressing these issues is essential for responsible development, supporting sustainability, and advancing global goals in green chemistry and public health.