Dual-modal biosensor based on proton-modulated mechanism integrated nanozyme for acetylcholinesterase analysis.

Background: Acetylcholinesterase (AChE) not only serves as an important biomarker for nervous system diseases, but also facilitates the discovery of related drugs. Therefore, the sensitive and accurate detection of AChE is of great significance for the diagnosis of relevant diseases and drug screening. Moreover, despite the great leaps in nanozyme-based sensing technology, it is still one of the challenges in the biomimetic field to design felicitous approaches to realize in-situ modulation of nanozyme activity. To address the above issues, a proton-modulated strategy for self-regulation of nanozyme activity was proposed, and then AChE was employed as a model analyte to construct a dual-mode colorimetric and electrochemical bioassay system.

Results: In this work, a novel nanozyme (7 % hemin-BiWO, H-BiWO) with specific peroxidase-like (POD) activity was exploited, which can activate 3,3',5,5'-tetramethylbenzidine (TMB) to produce oxTMB in the coexistence of hydrogen peroxide (HO). Whereas the latter (oxTMB) exhibits attractive optical yet electrochemical properties, thus leading to remarkable signal enhancement. In addition, in-situ regulation of nanozyme catalytic performance was achieved based on the fact that AChE could promote the hydrolysis of acetylcholine (ACh) to produce acetic acid, and then directly affect the pH of the solution. Thus, a self-modulated colorimetric and electrochemical dual-channel sensing strategy based on AChE activity was prepared, which not only allows quantitative analysis of AChE with detection limits of 0.04 mU/mL (colorimetric method) and 0.015 mU/mL (electrochemical method), but also successfully fulfil determination in spiked human blood samples with the recovery values ranging from 97.44 % to 107.66 %.

Significance And Novelty: Overall, a colorimetric-electrochemical dual-channel sensor based on the proton-regulation mechanism was constructed, which satisfied the "on-demand" determination of AChE, but also reached in-situ modulation of the catalytic activity of nanozyme. This study opens up a new avenue for the establishment of a self-regulating dual-mode analytical approach, and also provides new impetus for developing novel diagnostic methods of AChE-related diseases.