Near-infrared fluorescent probe for in vivo monitoring acetylcholinesterase activity

Acetylcholinesterase (AChE) plays an important role in the process of chemotherapy drug-induced cell apoptosis and is also an apoptosis marker to diagnose disease and assay the effect of the drug. Thus, we designed and synthesized a novel near-infrared fluorescent probe (NFL-SF) to detect AChE activity, which contained near-infrared (NIR) fluorophore NFL-OH and 2-thienylformyl chloride as the recognition unit. The probe has higher specificity and sensitivity to AChE and excellent biocompatibility. With the increasing concentration of AChE, the probe displayed an enhanced fluorescence signal at 745 nm for 30 min, with the detection limit of 0.2 mU/mL. In addition, NFL-SF not only detected exogenous AChE activity, but also effectively monitored the endogenous AChE activity of chemotherapeutic drug-induced cell apoptosis in living cells. When the AChE activity was inhibited with donepezil, the fluorescence intensity of the NIR channel was significantly reduced. Notably, the probe was successfully applied to in vivo imaging of nude mice. We believe that this probe could provide a strategy for rapidly and visually monitoring AChE activity.