Abstract

Background: Microbial biogenic selenium nanoparticles (SeNPs) have become promising agents in nanomedicine because of their environmentally friendly synthesis and potential anticancer properties. Objective: This review provides an updated overview of the synthesis of SeNPs by yeast and lactic acid bacteria, their physicochemical properties, anticancer mechanisms, and potential therapeutic applications, with a particular emphasis on their role in cancer treatment. Methods: A systematic search was performed on PubMed, Scopus, Web of Science, and ScienceDirect using keywords such as "selenium nanoparticles," "biogenic synthesis," "microbial," "anticancer activity," and "therapeutic potential." Articles published between 2010 and 2025 in English were included if they focused on the yeast and lactic acid bacteria synthesis of SeNPs and their biomedical applications. Duplicates, inaccessible texts, studies on non-microbial methods, and reports lacking biological evaluation were excluded. Approximately 108 articles were analyzed thematically based on synthesis, characterization, mechanisms, and applications. Results: Bacteria and yeast were identified as promising biosynthetic agents for SeNP production, showing indications of improved stability and biocompatibility. Characterization studies suggested that size-and shape-dependent properties may influence biological activity. Reported anticancer-related effects include ROSmediated apoptosis, DNA damage, cell cycle perturbation, and modulation of signaling pathways, with evidence of partial selectivity for cancer cells and lower toxicity to healthy tissues. Functionalization during microbial synthesis enhances solubility and cellular uptake, potentially improving therapeutic performance. Comparative analyses suggest that microbial SeNPs may offer advantages over chemically synthesized counterparts in safety and biological effectiveness. Conclusions: Microbial SeNPs represent sustainable nanomaterials with potential application in anticancer research. However, significant challenges remain, including the need for scalable production processes, greater standardization of synthesis protocols, and further preclinical and clinical evaluation to substantiate their therapeutic relevance.