Abstract
BACKGROUND: Given the great benefits of artificial enzymes, a simple approach is proposed via assembling of Ni(2+) with hemin for synthesis of Ni-hemin metal-organic-frameworks (Ni-hemin MOFs) mimic enzyme. The formation of the Ni-hemin MOFs was verified by scanning electron microscopy, Transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Energy-dispersive X-ray spectroscopy and UV-vis absorption spectroscopy. This novel nanocomposite exhibited surprising peroxidase like activity monitored by catalytic oxidation of a typical peroxidase substrate, 3,3,5,5'-tetramethylbenzidine, in the presence of H(2)O(2). By using folic acid conjugated MOF nanocomposite as a recognition element, we develop a colorimetric assay for the direct detection of cancer cells. RESULTS: The proposed sensor presented high sensitivity and selectivity for the detection of human breast cancer cells (MCF-7) and Human Caucasian gastric adenocarcinoma. By measuring UV-vis absorbance response, a wide detection range from 50 to 10(5) cells/mL with a detection limit as low as 10 cells/mLwas reached for MCF-7 cells. We further discuss therapeutics efficiency of Ni-hemin MOFs in the presence of H(2)O(2) and ascorbic acid. Peroxidase-mimic Ni-hemin MOFs as reactive oxygen species which could damage MCF-7 cancer cells, however for normal cells (human embryonic kidney HEK 293 cells) killing effect was negligible. CONCLUSIONS: Based on these behaviors, the developed method offers a fast, easy and cheap assay for the interest in future diagnostic and treatment application.