A 15-s Protein Separation Employing Hydrodynamic Force on a Microchip

We report here a novel pressurization technique for microchip electrophoresis that enables 15-s separation of protein mixtures extracted from biological samples. Although pressure-driven flow is usually parabolic flow, pressurization prior to electrophoresis separation produced a plug flow and achieved a dramatic migration time reduction without compromising resolution. Sample plugs were pushed forward by pressurization after loading the sample but before electrophoresis separation, in the absence of an electric potential. Higher pressures enabled higher speed separation; furthermore, the resolution could be easily controlled using an optimal pressure. In addition, the slow medium-pressurization technique enabled 2-D separation in only a single channel on a microchip. Utilizing this technique, 12 samples of complex protein mixture extracted from a human T lymphoblastic cell line, Jurkat cells, were separated within 15 s in a single run using a 12-microchannel array. In addition, target proteins from Jurkat cells were detected within this time. This novel pressurization technique on a microchip will offer enormous advantages for proteome analysis over commonly used 2-D electrophoresis.