Design and synthesis of fluorescent probe for high-sensitivity protein detection based on merocyanine structure and application to rapid electrophoretic gel stain

A new fluorescent molecular probe, sodium 3-((E)-2-((E)-3-(4-(dicyanomethylene)-6-methyl-4H-pyran-2-yl)allylidene)quinolin-1(2H)-yl)propane-1-sulfonate (1), possessing the cyanopyranyl moieties and merocyanine structure was designed and synthesized to detect proteins in solution and for SDS-PAGE. Compound 1 exhibited no fluorescence in the absence of proteins; however, it exhibited strong fluorescence on the addition of bovine serum albumin (BSA) as a result of polarity change by BSA. Compared with the conventional protocols for in-gel protein staining, such as SYPRO Ruby and silver staining, compound 1 achieves higher sensitivity, even though it offers a simplified, higher-throughput protocol. In fact, the total time required for protein staining was 60–90 min under optimum conditions much shorter than that required by the less-sensitive silver staining or SYPRO Ruby staining protocols. Thus, compound 1 may facilitate high-sensitivity protein detection, and it may be widely applicable as a convenient tool in various scientific and medical fields.