Green Synthesis of Selenium Nanoparticles Using Nigella sativa Seed Extract: Physicochemical Characterization and Antibacterial Activity

Abstract

Selenium nanoparticles (SeNPs) are increasingly investigated as multifunctional nanomaterials because their nanoscale physicochemical properties can be combined with selenium-dependent biological activity. Plant-mediated synthesis offers a comparatively simple route in which phytochemicals can participate in reduction and surface stabilization. In this study, SeNPs were prepared using Nigella sativa seed extract under aqueous and organic solvent conditions and were evaluated by UV–visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and well-diffusion antibacterial testing. The synthesized material showed a characteristic optical response, with an absorption feature around 270 nm for the organic preparation, while the aqueous preparation showed an extract-associated band around 430 nm. FTIR spectra indicated hydroxyl, C–H, carbonyl, and C–O/C–O–C containing groups associated with the plant-derived surface chemistry. XRD patterns showed crystalline diffraction features consistent with selenium-containing material, while SEM showed particulate morphology at the nanoscale morphology. Antibacterial activity increased with nanoparticle concentration. At 75 µg per well, inhibition zones reached 17.67 ± 0.47 mm against Bacillus subtilis, 16.33 ± 1.25 mm against Staphylococcus epidermidis, and 18.67 ± 0.94 mm against Salmonella Typhimurium. These findings support the use of plant-derived SeNPs as a sustainable antimicrobial platform and provide a foundation for future mechanistic, antibiofilm, cytotoxicity, and translational studies