Label-Free Fluorescence Turn-On Detection of Histidine-Tagged Proteins Based on Intramolecular Rigidification Induced Emission

Graphical We firstly reported the direct detection and quantification of His-tagged protein based on intramolecular rigidification induced emission in dilute solution, achieved the real-time and fast fluorescent “On” response of His-tagged proteins in protein solution. Our probe could be used in fluorescent labeling of proteins with simple procedure, high quality and low background interference. Histidine tag (His-tag) is a representative epitope tag, which has been widely used in the purification or immobilization of recombinant proteins. In this study, a novel probe CTPE-IDA-Ni 2+ based on intramolecular rigidification induced emission for fluorescence detecting His-tagged proteins is successfully developed and experimentally demonstrated. This detecting system is based on TPE derivative incorporated IDA-Ni 2+ moiety for real-time detection of His-tagged proteins. In the presence of His-tagged proteins, the IDA-Ni 2+ -His-tag complex was formed, which restricted the rotation of two phenyl rings linked with TPE and subsequently resulting in the fluorescence turn on. Results have shown that our probe could directly detect His-tagged proteins with good selectivity and fast response within 10 min. In addition, we have proved that this system could be used in fluorescent labeling of His-tagged protein instead of traditional Western blot assay with simple procedure, high quality and low background interference, as well as without aggregation-caused quenching (ACQ) problems like some organic dyes.