Manipulating the Photocatalytic Activity of Eu-Coordinated Hydrogen-Bonded Organic Framework Nanorods Decorated With Au Nanoclusters for the Multiplexed Luminescence Assay of Acetylcholinesterase

An integration of multiplexed luminescence and photocatalysis assay was proposed for the detection of acetylcholinesterase (AChE) by manipulating the coordination immobilization of photocatalytic Au nanoclusters on Eu-HOF nanorods. Eu-HOF-AuNCs served as a luminescence indicator and mimicked the enzyme toolbox for universally generating reactive oxygen species (ROS). Under light irradiation, Eu-HOF-AuNCs may accelerate the catalytic oxidation of oPD to produce more oligomers with yellow fluorescence and in situ-regulate photoluminescence variations of the indicator, in which oligomers can weaken the phosphorescence of the indicator based on overlapped spectra. By utilizing thiocholine (enzymolysis product of acetylthiocholine) to preferentially compete for ROS produced by photocatalysis of Eu-HOF-AuNCs, AChE activity was detected by the reversal of the indicator signal due to the attenuation of oPD oligomers. The emerged ratiometric fluorescence F573/F340 and F617/F340 exhibit improved sensitivity with detection limits of AChE as low as 0.09 and 0.14 U/L, respectively. Also, the cooperation of phosphorescence of Eu-HOF-AuNCs boosts detection accuracy. Serum experiments show that the Eu-HOF-AuNCs can be used to determine AChE, promoting the possibility of application in disease diagnosis. This sensor driven by photocatalysis has a great potential to be developed into a universal oxidase platform for quantifying analytes as long as the reasonable redox reaction.