In this work, fluorescent copper oxide nanoparticles (CuO NPs) were green synthesized using viable cells, cell lysate supernatant (CLS) and protein extracts of luminescent Vibrio sp. VLC. Biogenic CuO NPs were then characterized by XRD, FTIR, UV/Vis spectroscopy, TEM, DLS, and PL spectroscopy. Results showed that CLS method was more efficient for CuO NPs production, therefore CuO NPs synthesized by this method from copper sulfate (CuO NPs-1) and/or copper nitrate (CuO NPs-2) were used for further studies. The crystallite size of polydispersed CuO NPs-1 and CuO NPs-2 were about 8.83 and 8.77 nm, respectively indicating their suitability for biological applications. Antibacterial activity of CuO NPs was determined using broth microdilution, well diffusion agar, and time-kill curves methods. Both CuO NP-1 and CuO NP-2 inhibited bacterial growth at the minimum inhibitory concentration (MIC) of 625 mg/L except St. mutants (MIC=1250 mg/L). Emission of fluorescent light from the surface of NPs was increased when exposed to Cd2+, As2+ and Hg2+ ions but decreased by Pb2+ ions. Results showed that CuO NP-1 had anticancer properties against KYSE30 esophageal cancer cell line (IC50=13.96 mg/L) while no higher cytotoxic effects were observed on Human Dermal Fibroblasts (HDF) (IC50=48.88 mg/L).

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