Selenium nanoparticles as antioxidants: green synthesis, characterization, and evaluation of bioactivity

Selenium (Se), an important micronutrient with several biological effects, exhibits improved stability, biocompatibility, and safety through nanoparticle (NP) formulation. We present here a novel approach for producing smaller and structurally stable biogenic selenium nanoparticles (SeNPs) with bioactive coating. Poly(allylamine hydrochloride)-coated SeNPs were synthesized biogenically using <i>Trachyspermum ammi</i> (TA) seed extract, in parallel to chemically synthesized SeNPs. NPs were characterized and assessed for their <i>in vitro</i> antioxidant/radical scavenging potential through multiple complementary chemical assays along with the intracellular reactive oxygen species (ROS) scavenging and biocompatibility assay using human dermal fibroblasts. Both NPs were spherical and positively charged, with TA-SeNPs having a smaller size and a more amorphous nature. X-ray photoelectron spectroscopy confirmed the presence of elemental Se. Fourier transform infrared spectroscopy (FTIR) indicated the functional groups common to both NPs, with unique aliphatic, aromatic and glycosidic linkages, and phenolic compounds in TA-SeNPs, attributed to the TA extract. Both NPs showed dose-dependent antioxidative properties, with TA-SeNPs exhibiting significantly increased antioxidant activity among all the tested samples and showing similar to relatively higher activity relative to L-ascorbic acid (AA) and TA extract in several assays. Viability assays revealed that both NPs were nontoxic at low concentrations; however, cell viability is decreased at high concentrations, indicating dose-dependent cytotoxicity. TA-SeNPs suppressed reactive oxygen species more effectively at low concentrations, whereas SeNPs showed stronger activity at high concentrations. Our findings showed that the TA extract-mediated biosynthesis offers a cost-effective and biologically favorable route to produce SeNPs, with potential for safer antioxidant nanomedicine applications.