Construction of a copper nanocluster/MnO 2 nanosheet-based fluorescent platform for butyrylcholinesterase activity detection and anti-Alzheimer's drug screening.

An abnormal level of butyrylcholinesterase (BChE) activity is highly connected with hepatic damage and Alzheimer's disease. Herein, a facile and efficient method was proposed for BChE detection by incorporating polyethyleneimine-capped copper nanoclusters (PEI-CuNCs) with manganese dioxide (MnO 2 ) nanosheets. The emission of PEI-CuNCs can be significantly quenched by MnO 2 nanosheets via the inner filter effect. With the addition of BChE, the hydrolysis of butyrylthiocholine iodide produces thiocholine which can reduce MnO 2 nanosheets to Mn 2+ , thus resulting in the fluorescence recovery of PEI-CuNCs. Based on that, a fluorescence "turn-on" sensing platform for BChE activity determination was constructed with a detection limit of 2.26 U L -1 . This sensing method is able to detect BChE in human serum samples and identify the serums of normal persons and cirrhotic patients effectively, indicating its great potential in the clinical diagnosis of liver diseases. Furthermore, the approach can also be used to screen BChE inhibitors, which are promising medications to alleviate the symptoms of Alzheimer's disease.