Synthesis of NiO nanoparticles from Paulownia tomentosa plant extracts via a green synthesis method and antibacterial, antibiofilm and cytotoxicity applications

This study revealed the effective production of nickel oxide nanoparticles (NPs) using chelating agents derived from the leaves of Paulownia tomentosa plants and nickel (II) chloride hexahydrate (NiCl 2 ⋅6H 2 O) as the precursor. Nickel oxide NPs (NiO NPs) have been successfully prepared by a green synthesis method using extracts of P. tomentosa leaves in water. The morphology and crystallinity of the NPs were investigated via X‐ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy (UV–vis), energy‐dispersive X‐ray analysis (EDX), Fourier transform infrared spectroscopy (FT‐IR) and thermogravimetric analysis (TGA). The formation behaviour of NiO NPs and the microstructural and physical properties of the resulting particles were studied. This study additionally investigated the antimicrobial, antibiofilm and cytotoxic effects of NiO NPs. Microstructurally uniform NiO NPs with a nanometre diameter were consistently produced using an eco‐friendly processing approach and exhibited a visible‐range transparency of 89%. The obtained SEM images confirmed the octahedral shape of the NPs. The NiO NPs acquired were found to have potent antimicrobial efficacy against all the other bacterial strains. As a result of their antibiofilm effects on pathogenic Escherichia coli and Pseudomonas aeruginosa bacteria, NiO NPs strongly inhibited these bacteria in a concentration‐dependent manner. In the cytotoxicity study of NiO NPs, a decrease in cell viability was shown to occur depending on the concentration of the cell lines used.