Construction of logic gate computation for the assay of the nerve agent sarin based on an AChE-based dual-channel sensing system

Abstract

Nerve agents have posed a huge threat to national and human security, and their sensitive detection is crucial. Herein, based on the oxidation of Ce⁴⁺ and the aggregation-induced emission (AIE) of glutathione-protected gold nanoclusters (GSH-Au NCs), a cascade reaction was designed to prepare oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) and GSH-Au NCs crosslinked by Ce³⁺ (Ce³⁺-GSH-Au NCs). oxTMB had a broad UV-visible absorption range (500–700 nm) and was capable of quenching the fluorescence of Ce³⁺-GSH-Au NCs at 590 nm through the internal filtration effect (IFE). Thiocholine (TCh), the hydrolysis product of acetylthiocholine chloride (ATCl) catalyzed by acetylcholinesterase (AChE), reduced oxTMB completely, resulting in a decrease in the absorption of oxTMB and the recovery of IFE-quenched fluorescence of Ce³⁺-GSH-Au NCs. Nerve agent sarin (GB) hindered the production of TCh and the reduction of oxTMB by inhibiting the AChE activity, leading to the fluorescence of Ce³⁺-GSH-Au NCs being quenched again. The dual-output sensing system (AChE + ATCl + oxTMB + Ce³⁺-GSH-Au NCs) exhibited a low limit of detection to GB (2.46 nM for colorimetry and 1.18 nM for fluorimetry) and excellent selectivity toward common interferences being unable to inhibit AChE. Moreover, the intelligent logic gate constructed based on the sensing system showed promising applications in the field of smart sensing of nerve agents.