Recent Advances Towards Selenium Nanoparticles: Synthetic Methods, Functional Mechanisms, and Biological Applications

The exceptional physicochemical properties of selenium nanoparticles (SeNPs) have led to their widespread development. The function of SeNPs is significantly influenced by their shape and particle size, which are in turn determined by the applied synthesis methods. This work presents a critical and comparative analysis of physical, chemical, and biosynthetic methods. The key point is to elaborate on how different methods precisely regulate the particle size, morphology, and stability that are crucial to their functional efficacy. This work emphasizes the importance of creating standardized protocols for characterizing SeNPs in order to make meaningful comparisons between the effectiveness of various studies. We further elucidate the underlying mechanisms of SeNPs' anti-tumor, antioxidant, and antibacterial activities. A key novelty of this work lies in its systematic construction of a bridge between the synthesis, properties, functions, applications, and translational potential and its provision of a critical assessment. Finally, the review identifies and summarizes the principal challenges hindering clinical and commercial translation, including the imperative for standardized toxicological evaluation, scalable synthesis, and regulatory alignment.