Dual-mode colorimetric-photothermal sensing platform of acetylcholinesterase activity based on the peroxidase-like activity of Fe-N-C nanozyme

Sensors based on colorimetry, fluorescence, and electrochemistry have been widely employed to detect acetyl-cholinesterase and its inhibitors, however, there are only a minority of strategies for AChE detection based on photothermal method. This work reports a versatile dual-mode colorimetric and photothermal biosensing plat-form for acetylcholinesterase (AChE) detection and its inhibitor (paraoxon-ethyl, a model of AChE inhibitors) monitor based on Fe-N-C/H2O2/3,3 ',5,5 '-tetramethylbenzidine (TMB) system. The Fe-N-C with abundant active Fe-Nx sites shows outstanding peroxidase-mimicking activity and can be used to promote the generation of center dot OH by H(2)O(2 )to oxidize TMB. However, the introduction of mercapto molecules tending to coordinate with metal atoms result in the block of action site in Fe-N-C, thereby decrease its peroxidase-mimetic activity. The designed biosensor principle is based on the block of active sites of Fe-N-C by thiocholine (TCh, one kind of mercapto molecules) that can be produced by acetylthiocholine (ATCh) in the presence of AChE. Under optimum conditions, the limit of detection (LOD) for AChE activity is 1.9 mU mL(-1) (colorimetric) and 2.2 mU mL(-1) (photo -thermal), while for paraoxon-ethyl is 0.012 mu g mL(-1) (colorimetric) and 0.013 mu g mL(-1) (photothermal), respectively. The assay we proposed not only can be designed to monitor AChE detection and its inhibitors, but also can be easily extended for the detection of other biomolecules relate to the generation or consumption of H2O2.

Automated summary

This work reports a versatile dual-mode colorimetric and photothermal biosensing platform for acetylcholinesterase (AChE) detection and its inhibitor monitor based on Fe-N-C/H2O2/3,3',5,5'-tetramethylbenzidine (TMB) system. The platform shows outstanding sensitivity and selectivity, and can be easily extended for the detection of other biomolecules related to H2O2 generation or consumption.