Green Synthesis of Silver-Doped Nickel Oxide Nanoparticles Using Psidium Guajava Leaf Extract and Their Anti-Cancer Potential on Glioma Cells

Glioma is an aggressive brain tumor with limited therapeutic options, highlighting the need for the development of effective nanomaterial-based anticancer agents. In the present study, silver (Ag)-doped nickel oxide (NiO) nanoparticles were green synthesized using Psidium guajava leaf extract and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS). XRD confirmed the formation of crystalline cubic NiO with successful Ag incorporation, while FESEM revealed quasi-spherical nanoparticles with an agglomerated porous morphology. UV–Vis spectroscopy exhibited characteristic absorption bands at 268 and 398 nm, FTIR confirmed Ni–O vibrations and phytochemical functional groups involved in nanoparticle stabilization, and DLS analysis showed a median hydrodynamic diameter of 56.50 nm. The anticancer activity of the nanoparticles was evaluated against C6 rat glioma cells. Ag-doped NiO nanoparticles significantly decreased cell viability in a concentration-dependent manner after 72 h, with an IC₅₀ value of 24.67 µg/mL, and markedly increased lactate dehydrogenase (LDH) release, indicating enhanced cytotoxicity. Acridine orange/ethidium bromide staining demonstrated significant apoptosis induction, with apoptotic cells increasing to 36.67 ± 1.38