A highly specific two-photon fluorescent probe for real-time monitoring of acetylcholinesterase in neurogenic disorders in vivo

Acetylcholinesterase (AChE) hydrolyses choline into thiocholine, which is essential for cholinergic neurons to revert to their resting state following activation. Abnormal changes in AChE activity can directly affect nervous system function. Thus, the specific detection of AChE activity is urgently needed for elucidating the function of the nervous system and diagnosing AChE-related diseases. Current methods for detecting AChE activity have several limitations, including strong background interference and poor tissue penetration. Thus, we designed and synthesized a two-photon (TP) excited fluorescent probe, WZ-AChE, for the specific detection of AChE. Briefly, a carbamate bond was chosen to specifically recognize AChE, which can also be cleaved by AChE. The product, WZ, released strong deep red fluorescence signal under TP excitation at 800 nm. Our results showed that WZ-AChE can detect AChE activity in PC12 cells with both superior sensitivity and selectivity. In addition, we successfully applied WZ-AChE to a C. elegans Parkinson's disease (PD) model and a mouse model of depression. The findings revealed that AChE activity was greater in both disease models than in the control group. To summarize, a novel tool was created to investigate the mechanisms underlying PD and depression.