Determination of butyrylcholinesterase activity based on thiamine luminescence modulated by MnO2 nanosheets

In this paper, a novel strategy for biosensing butyrylcholinesterase (BChE) activity is developed based on manganese dioxide (MnO2) nanosheets to modulate the photoluminescence of thiamine (TH). The oxidase-like activity of MnO2 nanosheets enables them to catalyze the oxidation of non-fluorescent substrate TH to generate strong fluorescent thiochrome (TC). When the target BChE is introduced to form thiocholine in the presence of S-butyrylthiocholine iodide (BTCh), MnO2 nanosheets are reduced by thiocholine to Mn2+, resulting in the loss of their oxidase-like activity and the reduction of TC fluorescence. Based on this, a BChE activity fluorescence biosensor is constructed utilizing the luminescence behavior variation of TH and the oxidase-like activity of MnO2 nanosheets. The fluorescence biosensor shows a sensitive response to BChE, and the detection limit reaches 0.036 U L−1. In addition, the feasibility of the biosensor in real samples analysis is studied with satisfactory results.