Biosynthesis of selenium nanoparticles using Inonotus hispidus posing anti-tumor effects

In this study, bio-selenium nanoparticles (Bio-SeNPs) were synthesized via biotransformation of sodium selenite by Inonotus hispidus. The sodium selenite tolerance of I. hispidus and the production process of Bio-SeNPs were systematically examined. Optimal synthesis was achieved by adding sodium selenite to a final concentration of 0.25 mM on the third day of fermentation, followed by 3-4 days of additional incubation. Under these conditions, the highest Bio-SeNP yield (4.66 mg/mL), a sodium selenite reduction rate of 78.86%, and a selenium recovery rate of 12.42% were attained. Meanwhile, characterization of the synthesized nanoparticles revealed that they were amorphous, spherical, and composed of elemental (zero-valent) selenium, with particle sizes predominantly ranging from 53 to 146 nm. In vitro cytotoxicity assays demonstrated that Bio-SeNPs exhibited low toxicity toward HT22 normal neuronal cells, while exerting significant dose-dependent inhibitory effects on the proliferation of HepG2 (liver cancer) and MCF-7 (breast cancer) cell lines. Notably, the anti-tumor efficacy of Bio-SeNPs surpassed that of biomacromolecules derived from I. hispidus alone, indicating a synergistic or enhanced bioactivity conferred by the nanoparticle formulation.Mechanistically, Bio-SeNPs inhibited tumor cell growth predominantly by triggering early-stage apoptosis rather than necrosis, indicating the activation of intrinsic apoptotic pathways. These findings offer valuable insights into the scalable production of Bio-SeNPs and underscore their potential as targeted anticancer agents with minimal toxicity to normal cells.