Fluorescent light-up probe with aggregation-induced emission characteristics for in vivo imaging of cell apoptosis

In this paper, a new live-cell permeable, fluorescent light-up probe comprised of a hydrophilic caspase-specific Asp-Glu-Val-Asp (DEVD) peptide and a hydrophobic tetraphenylethene pyridinium unit has been developed for in vivo cell apoptosis imaging and drug screening. The probe shows a specific light-up response to activated caspase-3/7 with a high signal-to-background ratio. The significant fluorescence turn-on response of the probe is due to the aggregation of cleaved hydrophobic residues that populate the radiative decay channels. With good water solubility and biocompatibility, the probe is demonstrated to be a promising candidate for in vivo real time monitoring of caspase activation and in situ screening of apoptosis-inducing drugs.