By Geetha Yadav and Ning Liu
Polyacrylamide gel electrophoresis (PAGE) is a well-established technique for the separation, detection, and analysis of proteins. SDS-PAGE is used as the first step in western blotting analysis, in the second dimension separation of the 2-D analysis of proteins in proteomics studies, and as the confirmatory step in protein integrity and purity analyses after the chromatographic separation of proteins.
Visualization of proteins after separation on polyacrylamide gels is predominantly carried out using protein stains such as Coomassie Brilliant Blue (CBB). Other stains, such as silver, zinc or some fluorescent dye-based stains are also used to determine sample quality, level of separation, and protein load. The traditional staining methods are generally time consuming and preclude the use of gels in downstream applications, such as western blotting and mass spectrometry.
Stain-free technology, a technology that existed in principle since early 2000 but was only commercialized in 2010, addresses these issues and has, as a result, changed the protein separation and analysis landscape in the past few years. Stain-free technology has been adopted by many labs for its simplicity, ease of use, and, most important, its reliability, which confers validity to the results obtained in downstream applications. The number of stain-free gels has grown exponentially in the past three years.