A Fluorescent Probe with Aggregation-Induced Emission for Detecting Alkaline Phosphatase and Cell Imaging.

Alkaline phosphatase (ALP) is associated with many diseases, and its accurate detection is of great significance. Fluorescent compounds with aggregation-induced emission (AIE) feature show beneficial advantages for serving as fluorescent probes. Herein, an AIE-active "turn on" probe for ALP detection was synthesized through incorporating a strong electron-withdrawing group (cyano) in the middle and the recognition moiety phosphate group at the end, thereby rendering a D-A-D structure with a relatively high conjugation degree and good water solubility. It was found that the probe TPE-CN-pho is highly sensitive to ALP in aqueous solution. In the presence of ALP, the hydrophilic phosphate group on the probe is rapidly removed, resulting in a decrease in water solubility and subsequent formation of aggregates, thereby achieving aggregation-induced emission. Moreover, the probe TPE-CN-pho has also been successfully applied to imaging ALP in living cells.