Design and synthesis of ICT‐based fluorescent probe for high‐sensitivity protein detection and application to rapid protein staining for SDS‐PAGE

A novel fluorescent molecular probe possessing styryl, sulfonyl, and cyanopyranyl moieties that was termed compound 1 was designed and synthesized to detect proteins through noncovalent bonding. Compound 1 did not produce fluorescence emission in the absence of proteins. However, its fluorescence spectrum showed a dramatic increase in the fluorescence intensity and strong orange emission after the addition of BSA. These changes were caused by intramolecular charge transfer (ICT). The fluorescence intensities of compound 1 were plotted as a function of the protein concentrations. A good linear relationship was observed up to a protein concentration of 325 μg/mL, and the detection limit was 70 ng/mL under the given assay conditions; this detection limit was higher than that of previously reported compounds. To demonstrate the application of compound 1 , proteins in an SDS‐PAGE gel were stained with compound 1 and were successfully imaged with a higher sensitivity and shorter staining operation time as compared to those of the silver staining method and SYPRO Ruby staining method. Thus, easy and high‐sensitivity protein detection can be performed with the fluorescent probe, and this probe is ideally suited to proteomic applications.