Microfluidic Platform for the Evaluation of Multi-Glycan Expressions on Living Cells using Electrochemical Impedance Spectroscopy and Optical Microscope

A microfluidic platform to evaluate the expression of multi-glycans on a cell surface was developed using electrochemical impedance spectroscopy (EIS) and optical microscope technique. In the microfluidic channel, four indium tin oxide (ITO) electrodes were modified with three lectins and one passivation agent, respectively, to selectively recognize the corresponding carbohydrate epitopes on the cell surface. The binding of the cells on the electrode array was monitored by the electrochemical impedance to evaluate the expression of cell surface glycans. The excellent optical transparency of ITO electrode permitted the microscopic observation of the cell binding simultaneously to substantiate the impedance measurement. Compared with the individual technology, the double-check mode increased the sensitivity and accuracy of the assay. The experimental results using these two techniques indicated that the cell binding ability decreased in the order WGA > Con A > PNA, which was consistent with the expression difference of carbohydrate epitopes on K562 cell surface. The proposed strategy was further used for facile evaluating the variations of glycan expression on living cells in response to drugs. The consumption of cell sample for each sensing interface in the whole experiments is merely 5 x 10(3) cells. This platform offers great promise for cancer-associated glycol-biomarkers screening and further helps cancer diagnosis and treatment.