PVA-Stabilized Biogenic Selenium Nanoparticles: Physicochemical Properties and Ultrastructural Responses in Human Dermal Fibroblasts

Biogenic selenium nanoparticles (SeNPs) offer promising biomedical properties, although the polymeric environment can influence their physicochemical stability and cellular interactions. In this study, SeNPs synthesized using Amphipterygium glaucum leaf extract were incorporated into a medium-molecular-weight poly(vinyl alcohol) (PVA) matrix to obtain a redispersible SeNPs@PVA89 nanocomposite. Spectroscopic, structural, morphological, thermal, and dispersion analyses showed that incorporating SeNPs preserved characteristic nanoscale and optical features while altering polymer organization. The hydrodynamic diameter increased from 153 to 320 nm, and the ζ-potential shifted from −53 to −22 mV, consistent with changes in the nanoparticle interfacial environment and a hydrated PVA layer. In human dermal fibroblasts, SeNPs@PVA89 induced concentration-dependent effects: metabolic activity was preserved at 3 and 6 µg/mL, whereas ≥12 µg/mL markedly reduced cell viability; at 3 µg/mL, morphology, F-actin organization, and wound closure were preserved. Nevertheless, confocal microscopy revealed punctate intracellular fluorescence, while transmission electron microscopy showed electron-dense material within membrane-bound vesicles, alongside mitochondrial fragmentation, cristae alterations, and rough endoplasmic reticulum remodeling. Although the elemental identity of these electron-dense structures was not directly confirmed, the findings are consistent with cellular interaction and vesicular sequestration of the nanosystem. Overall, PVA-stabilized biogenic SeNPs showed concentration-dependent cellular effects, with ultrastructural remodeling despite unchanged conventional cytocompatibility outcomes.