Green Synthesis of Nickel Oxide Nanoparticles Using Leaf Extract of Aegle marmelos and Their Antibacterial, Anti-Oxidant, and In Vitro Cytotoxicity Activity

This present work employed a straightforward, green synthesis method to produce nickel oxide nanoparticles (NiO NPs) utilizing the leaf extract from the Aegle marmelos plant to improve their biological properties. NiO NPs have attracted considerable interest in recent years for their high chemical stability, catalytic performance, high surface area, biocompatibility, diverse applications, versatility, antimicrobial, anticancer, and antioxidant activity. The synthesized NPs underwent thorough characterization methods with UV–Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDAX), and transmission electron microscopy (TEM) analysis indicated the NiO NPs were predominantly monoclinic, cubic, and hexagonal in shape, exhibiting high purity and a general crystalline size ranging from 10 to 25 nm. EDAX analysis confirmed the presence of nickel and oxygen elements. The in vitro cytotoxicity of the NiO NPs was investigated on MC3t3-E1 cell lines treated with six different concentrations (25, 50, 100, 150, 200, and 250 μg mL⁻¹) for 48 h in comparison with a positive control, 5-fluorouracil, using the MTT test. Even though NiO NPs exhibit significant in vitro scavenging activity against DPPH and ABTS, it was observed to increase when compared to the standard ascorbic acid. Furthermore, NiO nanoparticles in aqueous solution also showed superior inhibition compared to streptomycin against both Bacillus subtilis (NCIM 2010), Escherichia coli (NCIM-5029), Staphylococcus aureus (NCIM-5022), and Streptococcus mutans (NCIM-5660) with inhibition zones measuring 13.7 ± 0.58 mm and 10.5 ± 0.50 mm. Hence, plant biomolecules induce the reduction of nickel ions to NiO NPs and function as a capping and stabilizing agent, enhancing biological performance. The findings indicated that the synthesis of NiO NPs from Aegle marmelos leaf extracts is a safe technology and exhibited good cytotoxicity and antioxidant activity.