Synthesis and Characterization of the Nanogold-Bound Ternary Copper(II) Complex of Phenanthroline and Cysteine as Potential Anticancer Agents

[Image: see text] The aim of this study was to synthesize and characterize a nanogold–{[(Cu)(phen)(cys)(H(2)O)]NO(3)}(n) conjugate and to evaluate its antiproliferative property against the breast cancer cell line (MCF7) and normal cell line (MCF10A). Nanogold solution was prepared using the Turkevich method. In one approach, a ternary copper(II) complex of 1,10-phenanthroline with l-cysteine, [(Cu)(phen)(cys)(H(2)O)]NO(3), was first prepared and then tethered with the gold nanoparticles. In another approach, gold nanoparticles were reacted with l-cysteine, copper(II) nitrate, and 1,10-phenanthroline subsequently. The synthesized [(Cu)(phen)(cys)(H(2)O)]NO(3) complex was characterized by Fourier transform infrared (FTIR) and electrospray ionization mass spectrometry techniques, which showed that l-cysteine was bound to the copper through carboxylic and amino groups, with the thiol moiety remaining free. The free thiol group was bound to the nanogold surface to form the nanogold–{[(Cu)(phen)(cys)(H(2)O)]NO(3)}(n) conjugate, as evidenced by the increase in the surface plasmon absorption band in ultraviolet–visible and the absence of a thiol peak in FTIR of the nanogold–copper complex conjugate. The anticancer activity of the nanogold–copper complex conjugate and the free copper complex against a breast cancer cell line (MCF7) and their toxicity on a normal cell line (MCF10A) were examined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy phenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Results suggested that the nanogold–{[(Cu)(phen)(cys)(H(2)O)]NO(3)}(n) conjugate demonstrates a selective antiproliferative and proapoptotic effect on the breast cancer cells, confirming the potential of the nanogold–copper complex conjugate as an anticancer agent.