RESUMO
A PMMA microfluidic chip, in which fluid is manipulated to transport protein from a PAGE gel piece to a collection reservoir via a microfluidic channel, has been developed. The protein sample is mobilized out of the gel (loaded in a chip access hole) into a low EOF-CE microfluidic channel under the influence of an electric field. Simultaneously, hydrostatic pressure from the filled buffer reservoirs is used to direct the protein sample to a third reservoir, through a field-free channel connected to the electrophoresis channel. Using this novel process of protein transport from a gel sample, proteins from Coomassie-stained gels have been transferred into solution in 15-30 min, with good sample recovery, using a run buffer containing an anionic acid-labile surfactant. A variety of small- and medium-sized proteins were successfully recovered and detected using both electrospray and MALDI MS over gel loads of 0.1-10 microg. This technological tool is very important for extracting quality intact protein samples from polyacrylamide gels, from which accurate protein molecular weights and protein sequences can be obtained using intact molecules.