Aggregation switched fluorescent strategy for acetylcholinesterase activity based on the controlled release of cationic perylene bisimide fluorophores

Abstract Acetylcholinesterase (AChE) is a vital cholinesterase for neural transmission which accounts for several nervous diseases, so a highly efficient sensing pattern for its determination is crucial. Upon an elegant integration of the aggregation-based response strategy and the intrinsic property of MnO2 nanosheets (NSs) in morphology and oxidability, a composite receptor PBM@MnO2 NSs for AChE was developed in this work, by virtue of the specific enzymatic interaction induced by AChE with positive thiocholine (TCh) as product to degrade MnO2 NSs and release N, N′-bis(2-(trimethylammonio)ethyl)-perylene-3,4,9,10-tetracarboxylic biimide (PBM) monomers. The electrostatic interaction between the positive PBM and negative MnO2 NSs is responsible for the self-assembly of PBM monomers onto MnO2 NSs, accompanied by the fluorescence quenching arising from PBM aggregation. The well-behaved selectivity toward AChE over other thiols (GSH, Cys and Hcy) is contributed by the charge property. The size of PBM aggregates were limited at ca. 150 nm, allowing further investigation on AChE evaluation biologically. This work examined the bio-imaging in cells and zebrafish, and in-depth study found out that this imaging platform is capable of discriminating cells at apoptosis from the living cells.