Synthesis and Characterization of Nickel Oxide Nanoparticles via Polyol‐Mediated Hydrothermal Process with Antibacterial Properties

Abstract Nickel oxide nanoparticles (NiO NPs) synthesized with polyvinylpyrrolidone (PVP) demonstrate promising antimicrobial properties for biomedical applications. NiO NPs were synthesized using PVP stabilizers of varying molecular weights: PVP K10 (average MW 10,000 dalton), PVP K15 (average MW 15,000 dalton), and PVP K40 (average MW 40,000 dalton), employing a hydrothermal method. The NiO NPs synthesized with PVP10K exhibited smaller particle sizes ranging from 30 to 40 nm and a larger surface area. Optimal synthesis conditions for NiO NPs were established as follows: 100 °C for 6 h for K1‐6/100, 120 °C for 6 h for K1‐6/120, and 120 °C for 12 h for K1‐12/120. TEM images revealed that the NiO NPs possessed a hexagonal morphology with sizes ranging between 10 and 30 nm. XRD analysis confirmed the crystalline structure of the NiO NPs, whereas FTIR spectra validated the presence of Ni─O bonds. UV–vis detected the optical bandgap within the range of 3.06 to 3.31 eV. The minimum inhibitory concentration assays indicated that the compound K1‐12/120 exhibited the most pronounced antibacterial effect against Escherichia coli at a concentration of 256 µg/mL and against Staphylococcus aureus at a concentration of 128 µg/mL. Moreover, Gram‐positive bacteria were found to be more susceptible to NiO NPs.