Green-synthesized selenium-doped nickel oxide nanoparticles: Biological activities and mechanistic insights into anticancer and antimicrobial effects

In this study, selenium-doped nickel oxide nanoparticles (Se–NiONPs) were successfully green synthesized using Rosa damascena leaf extract as a natural reducing and stabilizing agent. The novelty of the present work lies in the development of phyto-mediated Se–NiONPs with comprehensive multifunctional biomedical evaluation, including anticancer, antibacterial, antibiofilm, anti-virulence, antioxidant, and enzyme inhibitory activities. Phytochemical analysis confirmed the presence of phenolic and flavonoid compounds that contributed to nanoparticle formation and stabilization. The synthesized nanoparticles were characterized using UV–Vis, FTIR, XRD, SEM, TEM, EDX, elemental mapping, DLS, TGA, and BET analyses, confirming their crystalline nanoscale structure with an average particle size of 41.8 ± 20 nm and a zeta potential of + 15.1 mV. Cytotoxicity analysis revealed selective anticancer activity toward HeLa cells (IC₅₀ = 239.4 µg/mL) compared to normal Vero cells (IC₅₀ = 407.9 µg/mL) with a selectivity index of approximately 1.7. Flow cytometry demonstrated significant apoptosis induction and G2/M cell cycle arrest, while RT-qPCR analysis showed upregulation of caspase-3 and BAX and downregulation of Bcl-2, indicating activation of the mitochondrial apoptotic pathway. In addition, Se–NiONPs exhibited potent antibacterial activity against Pseudomonas aeruginosa , Staphylococcus aureus , and Escherichia coli , with inhibition zones ranging from 15.56 to 18.4 mm, MIC values of 200–400 µg/mL, and MBC values of 200–800 µg/mL. The nanoparticles also demonstrated concentration-dependent antibiofilm activity, achieving maximum inhibition percentages of 68.79%, 55.03%, and 52.89% against S. aureus , P. aeruginosa , and E. coli , respectively. Furthermore, Se–NiONPs caused significant bacterial membrane disruption reaching up to 54.64% and markedly downregulated key virulence genes, including lasB (55.40%), algD (46.36%), and toxA (41.28%). Moreover, the nanoparticles exhibited moderate antioxidant activity with DPPH and ABTS IC₅₀ values of 478.18 and 640.03 µg/mL, respectively, in addition to inhibitory activity against α-amylase and α-glucosidase enzymes with IC₅₀ values of 481.05 and 232.52 µg/mL, respectively. Overall, the findings suggest that green-synthesized Se–NiONPs represent promising multifunctional nanomaterials with potential biomedical relevance; however, further in vivo and biocompatibility investigations are required to validate their therapeutic applicability.