Studies On Acetylcholinesterase Electrochemical Sensor Based On RGO-TEPA/Cu NWs

Organophosphorus pesticides have played an irreplaceable role in protecting crops from diseases and pests,and also in increasing crop yields.However,extensive use of organophosphorus pesticides cause a series of negative impacts in environmental pollution,food safety,and human health,whiche can not be ignored.In recent years,with the development of nano science and technology,based on the excellent performance of nano materials to build the nano biosensors due to a short response time,low cost advantages,to provide on-site real-time detection of pesticide residue is a simple,rapid,accurate and effective methodIn this work,We constructed a new acetylcholinesterase（AChE）sensor combied reduced grapheneoxide-tetraethylene pentamin（rGO-TEPA）,copper nanowires（Cu NWs）,which was synthesised by a facile wet-chemistry approach,chitosan and glutaraldehyde based on the above research background.The nanocomposites of rGO-TEPA,with wrinkled morphology,and Cu NWs can form network-like structure,which could provides a large specificsurfaceareaforloadingacetylcholinesterase.Chitosan,withgood biocompatibility,forms mutual cross-linking with glutaraldehyde to firmly bond AChE on the electrode surface.The Cu NWs not only effectively catalyzed the oxidation of thiocholine（TCh）,but also lowered its oxidation potential to around 0.3 V.In this paper,we focus on the preparation and characterization of rGO-TEPA-Cu NWs nanocomposites and the properties and applications of the constructed AChE sensors.The results were as follows:（1）In the pursuit of more economical electrocatalysts for AChE sensor,the copper nanowires（Cu NWs）with a large aspect ratio were synthesized by a facile,scalable,wet-chemistry approach.The morphology and elemental composition of the as-prepared Cu NWs were examined by SEM and EDX.The results showed that one-dimensional Cu nanowires（Cu NWs）possess uniform size distribution and a large aspect ratio,and the elements of Cu,N,O and C derived from rGO-TEPA and Cu NWs,respectively.（2）The electrochemical behaviors of AChE sensor was thoroughly investigated by cyclic voltammetry and diffenential pulse voltanmmetry.The results showed that the appearance of an oxidation peak of around 0.3 V in the oxidation stage is the oxidation current response of the hydrolysate thiocholine under the excitation of the electrode.（3）The electrochemical behaviors of AChE sensor toward ATCl was thoroughly investigated by cyclic voltammetry.The results showed that the synergistic effect between Cu NWs and rGO-TEPA enhanced performance（4）The electrochemical behaviors of the fabricated AChE biosensor were evaluated by the typical cyclic voltammetry（CV）and electrical impedance spectroscopy（EIS）using potassium ferricyanide as an electrochemical probe respectively.As a result,the rGO-TEPA-Cu NWs nanocomposite greatly increased the electron transfer rate.After AChE posited onto the CS-Ti3C2Tx/GCE biosensor,the obtained peak currents slightlcreased.（5）The experimental conditions were optimized by diffenential pulse voltanmmetry（DPV）.The experimental conditions were determined as the ratio of rGO-TEPA to Cu NWs was 2:1;The modification amount of nanocomposites onto electrode was 6μL;The pH of the PBS was 7.4;The amount of modification of acetylcholinesterase onto electrode was 0.3 U;The concentration of ATCl was 2 mM ATCl;The incubation time of organophosphorus was10 minutes under optimized conditions.In order to optimize each parameter,all other parameters operate under their optimal conditions.（6）Under the optimal detection conditions,The linear range of the AChE sensor for malathion detection ranged from 0.01 ng/mL to 100 ng/mL with a detection limit of 0.01ng/mL.（7）The proposed AChE sensor exhibited good anti-interference toward CO₃^2-;PO₄^3-;NO₃^-glucose;dopamine,Cu²⁺;uric acid;ascorbic acid.At the same time,the sensor has good stability and repeatability.In a word,our sensor have great potential to become an effective platform for pesticide detection.