Selenium Nanoparticle–2D Material Hybrid Composites for Redox Regulation in Saccharomyces cerevisiae: Biochemical and Microchemical Insights

Abstract Selenium serves as an essential element and recognizes as for its vital biological significance by acting as cofactor. Despite its essentiality, dual role of selenium as a beneficial micronutrient at optimal concentrations and a potential pro-oxidant at high concentrations under external stress remains a critical area of investigation in Saccharomyces cerevisiae . However, advent of redox homeostasis regulator and stress controller green synthesized selenium nanoparticles (Se-NPs) has emerged as a promising solution. The research examines the dose-dependent effects of Se-NPs on the growth dynamics and glutathione redox cycle (GSH:GSSG) in Saccharomyces cerevisiae subjected to external stress conditions. Synthesized Se-NPs were prepared and confirmed by Ultraviolet–visible (UV–Vis) spectra at peak at 300 nm. Scanning electron microscopy (SEM) showed a spherical with irregular patterns of Se-NPs. The analysis by energy-dispersive X-ray spectroscopy (EDS) revealed a strong intensity of Se as compared to other elements. Yeast culture was exposed to selenium treatments at different concentrations: No selenium (control), < 0.1 mg/L, 0.1–1 mg/L, and > 2 mg/L, with evaluations focusing on microscopic morphology, spectroscopic absorbance (A600), cell counts and the redox equilibrium of the GSH:GSSG cycle in mitochondria, cytosol and nucleus under external stress conditions, including thermal stress, ethanol stress, H₂O₂ stress (oxidative damage), and HU stress (replication disruption). Selenium dose at 0.1–1 mg/L improved cell viability together with stress tolerance by preserving a high GSH:GSSG ratio which promote antioxidant defense whereas excessive selenium dose (> 2 mg/L) induced cytotoxicity and disrupted glutathione homeostasis leading to redox imbalance. These findings described a critical threshold for Se-NP bioactivity that identify its protective versus toxic effects. Understanding of selenium dose-dependent modulation in redox homeostasis provides fundamental insights into the potential biotechnological, redox biology and therapeutic applications along with stress management strategies.