In this study, we developed a new immunosensor that can achieve an ultralow detection limit and high sensitivity. This new device has an electrokinetic trapping (EKT)-based nanofluidic preconcentrator, which was integrated with oscillating bubble valves, to trap concentrated antigen and immunobeads. During the immunoassay process, oscillating bubbles rapidly grew and acted as control valves and to block the microchannel. Thereafter, the trapped preconcentrated antigen plug and antibody-coated nanobeads were preserved in the region between these two valves. Finally, the antigen concentration was quantitatively analyzed by a real-time measurement of Brownian diffusion of the immunobeads. In this work, the test sample used was C-reactive protein (CRP) which is a risk indicator of coronary heart disease and atherosclerosis.
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