Ratiometric and sensitivity detection of AChE: Silicon nanomaterial-triggered aggregation-induced emission of copper nanoclusters

As an important kind of hydrolase, acetylcholinesterase (AChE) is closely related to many neurological diseases. Therefore, the development of reliable and sensitive methods for the determination of its activity is of great research significance. In this work, silicon nanomaterials (SiNPs) with positive charge and glutathione-modified copper nanoclusters (CuNCs) with negative charge were designed to establish a ratiometric fluorescence system (SiNPs@CuNCs) based aggregation-induced emission (AIE) strategy. The SiNPs@CuNCs could directly detect the AChE activity without any intermediate quencher. Acetylthiocholine iodide could be catalyzed and hydrolyzed into thiocholine (TCh) by AChE. TCh could effectively quench the fluorescence intensity (FI) of CuNCs in SiNPs@CuNCS, yet the FI of SiNPs was unchanged. The activity of AChE was measured by FI ratio (FCuNCs/FSiNPs). The linear range of SiNPs@CuNCs for the quantitative detection of AChE was 0–0.05 U/mL, and the limit of detection was 0.003 U/mL. SiNPs@CuNCs successfully realized the trace detection of AChE activity in a real serum sample, and satisfactory results were obtained. This research will provide unique insights into the development of new ratiometric fluorescent nanomaterials for the determination of other hydrolase.