Immunoelectrophoresis of red blood cells performed on microcapillary chips

Immunoanalysis of blood cells on a microcapillary electrophoresis (nuCE) chip has been studied using sheep erythrocytes (ShE) as an example. Two different buffer solutions, the phosphate-buffered saline (PBS) and the gelatin veronal buffer (GVB) were examined in regard to the electrokinetic transport behavior of ShE suspended in these solutions inside the rectangular channel engraved on a quartz chip. This clarified two advantages of the use of GVB for on-chip cell electrophoresis: gelatin coatings prevent (i) nonspecific sticking of ShE on the channel wall, and cause (ii) an appreciable reduction in the zeta potential of the wall suppressing the electroosmotic flow of the buffer solution. As a result ShE suspended in the GVB can smoothly migrate from the cathode to the anode, which is the opposite flow direction of immunoglobulin G (IgG) antibodies under the physiological pH condition of 7.4. Based on these results, on-chip capillary cell immunoelectrophoresis of ShE and rabbit anti ShE antibodies (IgG) have been proposed and successfully accomplished using the GVB. It is demonstrated that the variation of the cell migration velocity originating from the change in the surface charge after binding antibodies is applicable to the fast detection of immune reactions and also to single-cell typing.