Fluorescent assay for acetylcholinesterase activity and inhibitor screening based on lanthanide organic/inorganic...

It is of great significance for the clinical diagnosis of Alzheimer's disease (AD) to achieve the on-site activity evaluation of acetylcholinesterase (AChE), the hydrolase of acetylcholine (ACh). Herein, we have developed a biosensing method endowed with considerable superiority based on the organic-inorganic hybrid composite Eu(DPA)₃@Lap with excellent stability and fluorescent properties for this purpose by loading Eu³⁺ ions and 2,6-dipicolinic acid (DPA) into LAPONITE® (Lap). Through the comprehensive consideration of the specific hydrolysis of acetylthiocholine (ATCh) into thiocholine (TCh) by AChE, the high binding affinity of TCh to copper ion (Cu²⁺), and the selective fluorescence quenching ability of Cu²⁺, a simple Eu(DPA)₃@Lap-based assay was developed to realize the rapid and convenient evaluation of AChE activity. Owning to the facile signal on-off-on response mode with a clear PET-based sensing mechanism, our assay presents favorable selectivity and sensitivity (LOD of 0.5 mU mL^-1). Furthermore, the fluorescent assay was successfully applied for assessing AChE activity in human serum samples and screening potential AChE inhibitors, showing potential for application in the early diagnosis and drug screening of AD, as a new development path of AD therapy.