Rapid subpicogram protein detection on a microchip without denaturing

Protein size separation based on sodium dodecyl sulfate-gel electrophoresis (SDS-GE) requires denaturing, but we propose that denaturing is unnecessary for analysis by microchip electrophoresis (micro-CE). By omitting the protein denaturing process, we achieved not only shortened total analysis time, but also dramatically improved sensitivity without compromising size determination. The detection limit was improved to 0.1 ng/microL under conditions without denaturing and 600 pg (9.0 femtomol) of bovine serum albumin was detectable, which equals levels detectable by Silver stain, although a routine method by microchips in the Coomassie Blue detection level.