Detection of surface immunoreactions on individual cells by electrophoretic mobility measurement in a micro-channel

The electric characteristics at the surface of cells are changed depending on the surface conditions and reactions, and electrophoresis is one of the simplest methods of detecting the change in the electric characteristics of cells, and one which does not cause any damage to the sample cells. In this paper, we fabricate micro-channels, attach antibodies, that is, immunoglobulin G (IgG), to the surface of sheep's red blood cells (RBCs) and carry out electrophoresis experiments of RBCs in the micro-channels to measure the electrophoretic mobility of each RBC. The amount of antigen-antibody reaction on the cell surface is also measured by the well-known enzyme-linked immunosorbent assay (ELISA) method. We find that there is a clear correlation between the electrophoretic mobility of the cells and the amount of IgG reaction on the surface of the cells, that is, the absolute value of the mobility of the cells decreases with an increase in the amount of IgG reaction on the cells. Therefore, the amount of surface reactions on each cell can be quickly detected by measuring the electrophoretic mobility of the cell, which is much simpler than labelling methods such as the ELISA or flow cytometric methods. The present result suggests that simultaneous detection of different diseases and health conditions may become possible by using multi-channel micro-fluidic electrophoresis devices. (c) 2007 Elsevier B.V. All rights reserved.