Target-responsive AIE-Au nanoconjugate for acetylcholinesterase activity and inhibitor assay with ultralow background noise

Fluorescence nanosensor with ultralow fluorescence background is in highly demand for enhancing the sensing performance. Herein, we report a kind of nonfluorescent nanoconjugates between aggregation induced emission nanoparticles and gold nanoparticles (denoted as AIE-Au nanoconjugates) through electrostatic interaction, and further implement them in sensitive analysis of acetylcholinesterase (AChE) activity and inhibitors. Acetylthiocholine (ATCh) was effectively catalyzed by AChE and subsequently hydrolysized into thiocholine, which interacted with AuNPs via the relatively strong Au-S bonds leading to the separation of AIE nanoparticles and AuNPs to recover AIE nanoparticles' fluorescence. Further, the proposed biosensor provided an ultrahigh sensitivity of 0.015 mU/mL for AChE. In view of the fact that AChE activity can be prohibited by inhibitors, AIE-Au nanoconjugates can also be applied for carbaryl analysis. On account of the exceptional properties, the prepared AIE-Au nanoconjugates broaden the perspectives of AIE nanoparticles and AuNPs for biosensor development, and demonstrated significant application prospect in food safety.