Selenium nanoparticles: Eco-friendly synthesis, biological activities and biomedical applications - A comprehensive review.

The green synthesis of nanoparticles has emerged as a promising, eco-friendly, and cost-effective alternative to conventional chemical and physical methods, offering significant biomedical potential due to their biocompatibility, stability, and multifunctionality. This review provides a comprehensive overview of recent advances in the biological synthesis of selenium nanoparticles (SeNPs) using bacteria, fungi, algae, and plants. It emphasizes the roles of various biological capping agents in modulating the physicochemical properties and therapeutic efficacy of SeNPs. The review critically examines the mechanisms underlying nanoparticle formation and stabilization, followed by in-depth discussions of their diverse biomedical applications, including antibacterial, antifungal, antiviral, anticancer, antioxidant, antidiabetic, and anti-inflammatory activities. Special attention is given to the unique ability of SeNPs to selectively target pathogenic cells while minimizing toxicity to healthy tissues, positioning them as promising candidates for nanomedicine. The synergistic effects of bioactive compounds used in the capping process further enhance their therapeutic profiles. This review aims to consolidate current knowledge on green-synthesized SeNPs, highlight the mechanisms and advantages of biogenic production routes, and explore their functional versatility across biomedical disciplines. Future directions include standardizing synthesis protocols, conducting detailed toxicological evaluations, and conducting translational research to integrate SeNPs into clinical applications. Moreover, advancing the design of SeNPs-based delivery systems and exploring their role in precision medicine and synergistic therapies will be essential for their sustainable use in next-generation therapeutics.