Bioinspired NiO nanoparticles from Bauhinia tomentosa with improved antimicrobial and antioxidant properties

Abstract Green synthesis approach of nanomaterials inspired by biological materials, in particular, extracts from plants, has become a preferred method to synthesize nanoparticles (NPs). This is mainly due to the improved therapeutic activity of the NPs informed by phytochemicals found in plant extracts, and the environmental friendliness and cost effectiveness of the method. The present work reports the bioinspired synthesis of nickel oxide NPs (NiO NPs) from the aqueous extract of Bauhinia tomentosa as reducing and capping agent. The morphology, functional groups, elemental composition, and size of the NiO NPs were characterized by scanning electron microscopy (SEM), Fourier transform Infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), and dynamic light scattering (DLS), respectively. The antioxidant and antimicrobial activities of the NPs were also investigated to test their therapeutic potential. The synthesized NiO NPs were spherically shaped and appropriately dispersed with a size distribution of 30–100 nm, and absorb at 346 nm in the ultraviolet region. The FTIR spectra of the NiO NPs revealed a stretching vibration band at 601 nm, representing the Ni-O bond. The bioinspired NiO NPs showed improved antioxidant activities over the extracts by scavenging the free radicals generated by hydrogen peroxide (H 2 O 2 ) and 2,2-diphenyl-2-picrylhydrazyl (DPPH). Furthermore, the NiO NPs showed outstanding activities against Escherichia coli , Pseudomonas aeruginosa , Staphylococcus aureus , and Candida albicans , comparable to popularly used antibiotics and antimycotics.