Spatially-multiplexed protein separations enabled by multifunctional photopolymerized gels

A 2-D microfluidic chip combining isoelectric focusing (IEF) and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) using photopolymerized polyacrylamide (PAAm) is described. In addition to serving as a highlyresolving separation medium for gel electrophoresis, the PAAm gels are used to enable the efficient isolation of different on-chip media including anolyte, catholyte, and sample/ampholyte solutions for IEF. The gel plugs are demonstrated as on-chip reagent containers, holding defined quantities of SDS for in situ SDS-protein complexation, and enabling the use of a discontinuous buffer system for sample band sharpening during SDS-PAGE.The new chip design also provides lossless sample injection and the optimized backbiasing to minimize sample tailing and leakage.