On-chip multi-dimensional biomolecule separation using multi-layer microfabricated valves

Abstract

Recent proteomics researches require a sensitive, high-speed, and automatic protein separation tool that far exceeds the capability of traditional two dimensional (2D) protein gel electrophoresis. Methods are described to achieve multi-dimensional biomolecule separation in a microfluidic channel. The new methods couple isoelectric focusing (IEF) with high ionic strength capillary electrophoresis (CE) by active micro valve control in a microchip. Several experiments demonstrating independent 2D separation were performed, and critical parameters for better chip performance were identified; including channel passivation, electroosmosis control, IEF linearity control, and detection enhancement. The result can be used for the filtration of high-abundance proteins, which used to be done by affinity columns. Also, it can be used for much possible integration between different heterogeneous separation/analysis techniques such as IEF, polyacrylamide gel electrophoresis (PAGE), CE, reverse-phase chromatography, and mass spectrometry (MS).