Green synthesis of nickel oxide nanoparticles using Zanthoxylum rhetsa (Roxb.) DC. leaf extract, comprehensive physicochemical characterisation and multifunctional biomedical applications

In the present study, nickel oxide nanoparticles (NiONPs) were synthesized through a green and sustainable method using aqueous leaf extract of Zanthoxylum rhetsa (Roxb.) DC. Phytochemicals present in the extract acted as natural reducing and stabilizing agents, enabling eco-friendly biosynthesis of the nanoparticles. The formation of ZR-NiONPs was confirmed by X-ray diffraction (XRD) which revealed an average crystallite size of 12.88 nm. Ultraviolet-Visible (UV-Vi) spectroscopy showed a characteristic absorption peak at 476 nm. Fourier Transform Infrared (FTIR) spectroscopy identified functional groups such as hydroxyl, carbonyl and amide groups along with a Ni-O stretching peak between 550 and 430 cm−1. Morphological analysis using Field Emission Gun-Scanning Electron Microscopy (FEG-SEM) revealed spherical to irregularly shaped particles. Energy Dispersive X-ray Spectroscopy (EDX) confirmed the presence of nickel and oxygen. Transmission Electron Microscopy (TEM) showed particle sizes ranging from 10 to 42 nm, while zeta potential (ZP) analysis indicated −10.2 mV suggesting moderate colloidal stability. Vibrating Sample Magnetometer (VSM) analysis revealed a magnetization value of ± 55 emu/g, indicating ferromagnetic nature. Biological studies showed significant antibacterial activity against Bacillus cereus ATCC 14579, Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922 and Proteus vulgaris ATCC 29905 and antifungal activity against Candida albicans (ATCC 10231) and Aspergillus niger (ATCC 16888). The nanoparticles exhibited antioxidant activity (IC50 = 92.56 µg/mL), anti-inflammatory activity (48.83% inhibition at 100 µg/mL), antidiabetic activity (IC50 = 97.71 µg/mL), anti-tuberculosis activity (46.24% inhibition at 1000 µg/mL), anticancer activity against MCF-7 cells (IC50 = 88.52 µg/mL) and cytotoxicity against L929 fibroblast cells (29.40% inhibition at 1000 µg/mL) indicating their potential for biomedical applications.