Abstract
Liver cancer is one of the most widely spread cancers in the world. Cancer stem cells (CSCs) are a small subpopulation of liver cancer cells that are thought to be responsible for relapse of cancer and the resistance to chemotherapy. Detection of CSCs is highly demanded for screening patients who are at high risk for developing metastatic cancers. However, the current methodologies for CSCs detection are sophisticated, expensive and not reliable. Here, we report the development of a label-free impedance immunosensors for liver CSC quantification using four established CSC surface biomarkers (CD44, CD90, CD133/2 and OV-6). The immunosensors were simply fabricated by the covalent attachment of four biomarkers specific antibodies on gold electrodes using cysteamine/phenylene isothiocyanate linker. Electrochemical impedance spectroscopy was employed to detect the binding of the cells to the immunosensors. The binding of the CSCs to the gold electrode surface retards the access of ferri-ferrocyanide redox molecules to the electrode leading to enhancement in the charge transfer resistance (R-ct) which represents the basis of the detection signal. The developed electrochemical immunosensors showed high sensitivity and selectivity for CSC detection with a wide linear range from 1 x 10(1) to 1 x 10(4) cells/mL with a limit of detection of 1 cell/ml. This work represents a new, accurate, simple and low cost method for the detection of liver CSC that might help in the early diagnosis of metastatic disease and cancer relapse.