Microfluidic two-dimensional IEF-CZE for proteomics

Separations of complex proteomes are required to fractionate components before downstream identification and quantification of individual protein species. Twodimensional gels based on a combination of isoelectric focusing (IEF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) have been a core technology for real-word detection of thousands of proteins, and microfluidic systems which mimic the functionality of 2-D gels in a miniature high-throughput format are a promising technology. Here we describe a new approach based on the combination of IEF with parallel capillary zone electrophoresis (CZE) in a microchip format, enabling improved reproducibility and higher throughput separations by eliminating the use of sieving gel in the second separation dimension. Although the system sacrifices some degree of resolving power through the use of non-orthogonal separation modes, overall peak capacities on the order of 2,500 are realized in the 2-D microfluidic chips.