Physics Department, College of Science, Mustansiriyah University, Baghdad, Iraq

Recent research has concentrated on the enlargement of new biomedical agents.

Consequently, the biosynthesis of nanoparticles has garnered important attention in recent years as a result of the increased development of new pathogens and microbial resistance against antibiotic therapy. The green synthesis approach is used in this work to generate “nickel oxide nanoparticles” NiO NPs utilizing nickel nitrate as a starting material and plant extracts from rosemary as a reducing agent and coating. Multiple characterization techniques have been used to classify the composite nanoparticles, including XRD, which confirmed the crystallinity of NiO NPs at face centered cubic phase at average size of crystalline is 13.59 nm. Fourier transform infrared spectra confirmed the NiO formation with high purity phase, which was found at the range 827 (cm-1). The FE-SEM shows that the nanoparticle size is 17.69 nm, with spherical and semi-spherical forms of the Nano clusters, which is in good agreement with the XRD data. And according to AFM, the average size of particle of NPs is 57 nm. NiO NPs have an optical bandage of 3.8 and 4.5 eV, and notable emission peaks were seen in the visible and ultraviolet regions. Agar well diffusion was used to test the antimicrobial behavior of green synthesized nanoparticles against four distinct bacterial species: S. epidermidisa, S. aurous, K. pneumonia, E. coli, and C. albino's fungi. The results showed significant antimicrobial activity over time and at varying concentrations, and an MTT assay was used to determine the anticancer activity against human colon cancer cells (CL-40).Even at very low concentrations, NiO nanoparticles showed significant anti-cancer effects against human colon cancer cells CL- 40 (IC50 : 69.20µg/mL). These findings imply that the synergistic effect of the green synthesized NiO nanoparticles physical characteristics and adsorbed phytomolecules on their surface may be responsible for their increased biological activities. “These results raise the possibility that NiO has new biological uses, such as as an antibacterial and anticancer agent” .