Rapid Isoelectric Focusing of Proteins in 1 Mm Long Microchannels

Isoelectric focusing (IEF) is used to separate proteins in millimeter long, agarose-filled microchannels. The agarose suppresses convection due to hydrostatic and electroosmotic flows that might otherwise occur in very short channels while loading or running the samples. Our experiments were performed in PMMA microchannels with lengths ranging from 1-10 mm at a constant field strength of 50 V/cm and these separations were recorded using whole channel imaging with fluorescent proteins. Narrow focused protein bands were usually observed in less than 1 min, but resolution slowly improved if several extra minutes were allowed to pass.