Gold nanoclusters–Cu2+ ensemble-based fluorescence turn-on and real-time assay for acetylcholinesterase activity and inhibitor screening

Based on the specific binding of Cu2+ ions to the 11-mercaptoundecanoic acid (11-MUA)-protected AuNCs with intense orange–red emission, we have proposed and constructed a novel fluorescent nanomaterials–metal ions ensemble at a nonfluorescence off-state. Subsequently, an AuNCs@11-MUA–Cu2+ ensemble-based fluorescent chemosensor, which is amenable to convenient, sensitive, selective, turn-on and real-time assay of acetylcholinesterase (AChE), could be developed by using acetylthiocholine (ATCh) as the substrate. Herein, the sensing ensemble solution exhibits a marvelous fluorescent enhancement in the presence of AChE and ATCh, where AChE hydrolyzes its active substrate ATCh into thiocholine (TCh), and then TCh captures Cu2+ from the ensemble, accompanied by the conversion from fluorescence off-state to on-state of the AuNCs. The AChE activity could be detected less than 0.05mU/mL within a good linear range from 0.05 to 2.5mU/mL. Our proposed fluorescence assay can be utilized to evaluate the AChE activity quantitatively in real biological sample, and furthermore to screen the inhibitor of AChE. As far as we know, the present study has reported the first analytical proposal for sensing AChE activity in real time by using a fluorescent nanomaterials–Cu2+ ensemble or focusing on the Cu2+-triggered fluorescence quenching/recovery. This strategy paves a new avenue for exploring the biosensing applications of fluorescent AuNCs, and presents the prospect of AuNCs@11-MUA–Cu2+ ensemble as versatile enzyme activity assay platforms by means of other appropriate substrates/analytes. [Display omitted] Seizing Cu2+ and recovering fluorescence by the product of ATCh hydrolyzed by AChE.Establishing AuNCs–Cu2+ ensemble-based real-time fluorescence turn-on assay for AChE.Assaying AChE activity less than 0.05mU/mL with linear range from 0.05 to 2.5mU/mL.A novel method to detect AChE in real biological sample and screen its inhibitors.