Photoresponsive Nickel(II) Complex with Enhanced Anticancer Activity: Insights into Biomolecular Interaction and Theoretical Studies

Metallodrugs with mechanisms distinct from cisplatin are promising for overcoming drug resistance and enhancing anticancer efficacy. In this study, a bipyridine-based ligand and its Ni(II) complex were synthesized and characterized using elemental analysis, nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF), ultraviolet-visible (UV-vis), Fourier transform infrared (FT-IR), and electrochemical techniques. Density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level supported the molecular structure. Interaction with calf thymus DNA and bovine serum albumin was confirmed through spectroscopic and biophysical methods, supported by molecular docking studies. The Ni(II) complex exhibited significant cytotoxicity against MG-63 and HCT-116 cancer cells under both dark and near-infrared irradiation, with low toxicity toward normal HEK293 cells. It showed higher activity than the free ligand, along with notable antioxidant and antimicrobial properties. Additionally, efficient photocatalytic degradation of Eosin Y (up to 93% under irradiation) highlights its multifunctional potential in biomedical and environmental applications.