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Protection of HeLa cells against ROS stress by CuZnSOD mimic system

Fang, Ya-Cheng, Chen, Yi-Ping, Chen, Chien-Tsu, Lin, Tien-Sung, Mou, Chung-Yuan
Journal of materials chemistry B 2013 v.1 no.44 pp. 6042-6052
Western blotting, antioxidant enzymes, catalytic activity, cell cycle, cell viability, copper, encapsulation, flow cytometry, fluorescein, human cell lines, isothiocyanates, nanocarriers, nanoparticles, paraquat, perchlorates, porous media, silica, superoxide dismutase, zinc
A new copper zinc complex (CZpbi), [(bipyridinyl)₂Cu-μ-pbi-Zn(pbi)](ClO₄)₂, pbi = 2-(2-pyridyl)-benzimidazole, was synthesized to mimic copper zinc superoxide dismutase (CuZnSOD). CZpbi was then encapsulated onto a dye (fluorescein isothiocyanate, FITC) functionalized mesoporous silica nanoparticles (MSN) where MSN serves as a nanofactory platform for delivering the catalytic action of the center copper complex. We examined the inhibition of oxidative damage of HeLa cells in the presence of paraquat (PQ, 1,1′-dimethyl-4,4′-bipyridylium dichloride, an oxidative stressor). We further studied the cell viability and cell cycle process under the influence of paraquat stress in the presence of the SOD-mimic FITC–MSN–CZpbi material by flow cytometry and western blot test. We found the nano-sized FITC–MSN is an excellent nano-carrier for delivering the mimic SOD complexes to HeLa cells. Here the reactants are already inside the cell and the result is a promotion of cell function. We present the methodology of encapsulating bio-inspired SOD-mimic in FITC–MSN to achieve a better drug delivery vehicle and catalytic (detoxification) activity. The potency and the stability of SOD-mimic FITC–MSN–CZpbi may provide a new avenue in the future development of artificial antioxidant enzymes.