Gel-staining techniques : dyeing to know it all

Staining techniques are the primary method for quantitative detection of gel-resolved proteins. With stain sensitivity defining the extent of total protein detected, staining-technique enhancements that facilitate increased detection of low-abundance proteins are constantly sought. Although stains must exhibit high detection sensitivity, they must also be broadly applicable, practical, cost-effective and compatible with downstream identification techniques. Currently, the most widely utilised in-gel protein stains are colloidal Coomassie Brilliant Blue and SYPRO Ruby (or slight variants on each). As with any stain, each requires extensive characterisation and rigorous optimisation of protocols to effectively define limits of sensitivity and quantitative capacity. However, the procedures involved in preparing, resolving, imaging and analysing samples can also have significant consequences on quantitative outcomes, and thus must be fully considered in order to facilitate detailed and reproducible analyses (i.e. as required in top-down proteomics).