A fluorescent probe with aggregation-induced emission characteristics for distinguishing homocysteine over cysteine and glutathione

The development of a fluorescent probe for homocysteine (Hcy) has received great attention in recent years because abnormal levels of Hcy in the blood is a risk factor for cardiovascular and neurodegenerative diseases. We herein report a tetraphenylethene derivative, TPE-Py, with aggregationinduced emission (AIE) characteristics. It contains an alpha,beta-unsaturated ketone unit and can react with biothiols through the 1,4-addition reaction route, which results in the disruption of molecular conjugation and thus leads to the change of its fluorescence. Due to the intrinsic AIE property of TPE-Py, only Hcy triggers an obvious ratiometric change from yellow emission to blue, whereas the quenching of fluorescence was observed in the case of cysteine (Cys) and glutathione (GSH), respectively. It enables TPE-Py to serve as a highly selective and sensitive probe for distinguishing Hcy over Cys and GSH.