Plant-mediated nickel oxide nanoparticles show species-dependent antibacterial, antioxidant, anti-inflammatory and antidiabetic activities.

Nickel oxide nanoparticles are renowned for their diverse properties, including magnetic, electrical, optical, and catalytic capabilities, making them highly suitable for both industrial and biomedical applications. This study synthesized nickel oxide nanoparticles using both chemical and green synthesis methods with extracts from four plant species: Medicago sativa L., Euphorbia milii Des Moul., Codiaeum variegatum (L.) A. Juss., and Helianthus annuus L. All samples had consistent face-centered cubic structures, as proven by X-ray diffraction. However, electron microscopy and Fourier-transform infrared spectra showed that the green-synthesized particles had tighter size distributions and unique surface functions due to the presence of plant phytochemicals. According to in vitro tests, Codiaeum variegatum mediated nanoparticles showed the strongest multifunctional bioactivity, including increased scavenging of free radicals, targeted cytotoxicity against A549 lung cancer cells, and substantial inhibition of cyclooxygenase-1 and important enzymes that hydrolyze carbohydrates. Antibacterial tests demonstrated that Staphylococcus aureus was efficiently reduced by both chemically produced and Codiaeum variegatum derived nanoparticles, whereas biofilm experiments shown that Medicago sativa derived nanoparticles caused greater disruption. These findings demonstrate that the performance of nanoparticles is controlled by their botanical source, allowing NiO nanoparticles to be tailored for specific medicinal uses. Our results open the door for additional in vivo testing and process optimization while validating green synthesis as an environmentally responsible method of producing NiO nanoparticles with adjustable bioactivities.