Tetraphenylethylene conjugated with a specific peptide as a fluorescence turn-on bioprobe for the highly specific detection and tracing of tumor markers in live cancer cells.

Smart molecular probes and flexible methods are attracting remarkable interest for the visualization of cancer-related biological and chemical events. In this work, a new fluorescence turn-on probe with dual-recognition characteristics for the specific imaging of cancer cells is reported. This new bioprobe is rationally designed by linking tetraphenylethylene (TPE), an aggregation-induced emission (AIE) fluorophore, with the small peptide IHGHHIISVG (referred to as AP2H), a targeting ligand to the broad-spectrum cancer-related protein LAPTM4B. The binding of the probe TPE-AP2H with the target, both in solution and at the cellular level, switches on the fluorescence of TPE because of the inhibition of internal rotations within the TPE framework. Accordingly, this bioprobe allows the real-time monitoring and subcellular localization of LAPTM4B in cancer cells, with a very high target-to-background ratio for the imaging. Furthermore, brighter fluorescence images are detected after incubation of TPE-AP2H with tumor cells at lower pH values. Thus, this new bioprobe is more advantageous because it can simultaneously target the LAPTM4B protein and sense the characteristic low-pH environment of tumor cells. In addition, TPE-AP2H displays high photostability and low cytotoxicity. Therefore, this new bioprobe is promising for the more accurate and reliable imaging of tumor markers in live cancer cells.