Design And Application Of Novel Polymeric Ionic Liquids Based Acetylcholinesterase Electrochemical Biosensor

It is important to establish a rapid and in-situ analysis method for pesticides and their derivatives.Amperometric acetylcholinesterase（ACh E）biosensor has been proved to be a reasonable solution because of its advantages of quick response,simplicity,convenience and low analytical cost.In order to construct a high-performance biosensor,it is crucial to select an appropriate immobilization method and support matrix to maintain the bioactivity of ACh E and accelerate electron transfer.In this paper,the biosensors were based on polymeric ionic liquid（PILs）microgel entrapped with ACh E（ACh E@PILs）.Under weak alkaline conditions,the negative charged ACh E on the surface interacts strongly with the positive charged ionic liquid monomer.Under the action of the template,the ionic liquid monomer emulsion polymerized into PILs,and in this process,the entrapped ACh E and PILs formed ACh E@PILs.On the one hand,positive charged PILs around the enzyme molecules provided a microenvironment biological compatibility,stabilized the biological activity and prevented the leakage.On the other hand,as a modifiable interface,PILs allow other components with electronic transmission characteristics load on them.Based on the above research,this paper mainly carries out the following work:（1）Firstly,Au nanoparticles（Au NPs）were selected as the first support matrix with high electron transport characteristics.ACh E@PILs@Au NPs were prepared by electrostatic assembly of Au NPs with negative charge properties on the basis of binary component ACh E@PILs.The limits of detection for carbaryl and dichlorvos by ACh E@PILs@Au NPs/GCE were 5.1×10^-2and 3.8×10^-2ng m L^-1,respectively.The linear ranges were 6.25×10^-2-8.75×10~2and 1.25×10^-1-1.375×10~3ng m L^-1,respectively.More importantly,the biosensor has ultra-high thermal stability and storage stability,facilitating rapid field detection of fruits and vegetables in a variety of climatic conditions.In addition,the biosensor had good repeatability and anti-interference ability,and had high accuracy in the analysis of peaches,tap water and other practical samples.（2）The influence of construction mode on electrochemical biosensor was further explored.Carboxylic multi-walled carbon nanotubes（c-MWCNTs）were selected as the second support matrix with high electron transport characteristics.Two c-MWCNTs with different charge properties were selected as a comparison to prepare electrode materials.The negative charged c-MWCNT-1 and ACh E@PILs were prepared to construct ACh E@PILs/c-MWCNT-1 by electrostatic assembly method,while the electrically neutral c-MWCNT-3 and ACh E@PILs were prepared to construct ACh E@PILs/c-MWCNT-3 by simple mixing method.The as-prepared electrochemicalbiosensorACh E@PILs/c-MWCNT-1/GCEand ACh E@PILs/c-MWCNT-3/GCE differed significantly under the same substrate concentration,and the peak current of the former was 1.96 times of the latter.The limits of detection for chlorpyrifos were 1.22×10^-2ng m L^-1and 2.73×10^-2ng m L^-1,and the linear ranges were 6.25×10^-2-6.25×10~2ng m L^-1and 6.25×10^-1-1.00×10~3ng mL^-1,respectively.