Preparation Of Mxene Nanocomposites And Study On Electrochemical Sensors

Biomolecularanalysis is crucial fordisease diagnosis,food safety inspection,environmental monitoring and drug development.However,the large precision instruments required by conventional detection methods are costly and complicated to operate.Therefore,the development trend of the future is to establish a simple,rapid and accurate method forthe detection of biological molecules.Electrochemical methods are widely used in biochemical analysis and electrochemical sensing due to theirconvenient operation and high sensitivity.It is also a crucial step to select suitable interface materials as modifiers forelectrochemical sensors to recognize biomolecules.Based on the above background,this papermainly used MXene（Ti₃C₂T_x）material to modify the electrochemical sensorinterface and study the performance of electrochemical sensor.The electrochemical sensorwas constructed to analyze and detect quercetin,hemoglobin（Hb）,dopamine（DA）and indole-3-acetic acid（IAA）.The specific work is as follows:1.The electrochemical detection performance of glassy carbon electrode（GCE）was improved by modifying two-dimensional MXene.Firstly,the morphological and structural characteristics of MXene were studied by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）,and it was found that MXene was a kind of two-dimensional layered material similarto accordion.Secondly,the electrochemical properties of MXene/GCE were studied by various methods.The direct electrochemical reaction of quercetin was studied and a pairof well-shaped redox peaks with a distance of 67 m V appeared on the cyclic voltammetry（CV）curve.The electrochemical parameters,such as electron transfernumber（n）,electron transfercoefficient（α）and reaction rate constant（k_s）,were calculated as 1.99,0.65 and 0.29 s^-1,respectively.In addition,the detection limit of the prepared sensorwas 33 nmol/L（3S₀/S）.Finally,MXene/GCE was used to analyze the content of quercetin in ginkgo tablets,and the recovery was 100.92%～104.66%.MXene/GCE have good anti-interference performance,stability and reproducibility forquercetin detection.2.Reduced graphene oxide（rGO）and MXene were synthesized by self-assembly method and used forelectrochemical study of Hb.The rGO-MXene nanocomposites were characterized by SEM,TEM,X-ray diffraction（XRD）.Hb electrochemical biosensorwas prepared on the nanocomposite modified electrode forthe determination of trichloroacetic acid（TCA）and hydrogen peroxide（H₂O₂）.The direct electrochemical behaviorof Hb on the modified electrode was investigated by calculating n,αand k_s.The modification of rGO-MXene nanocomposites on the electrode can improve the effective surface area and biocompatibility of the electrode interface,and obtain higherelectron transferrate.In addition,the electrochemical biosensorshowed good stability in TCA and H₂O₂ analysis.3.A novel DA sensing system was constructed by dropping gold nanoparticles（AuNPs）and MXene materials on GCE,and its microstructure was studied by SEM and TEM.The presence of AuNPs/MXene composites can significantly expand the electrochemical active surface area of the sensorand promote electron transfer,thereby enhancing the response signal.Underthe optimal experimental parameters,AuNPs/MXene/GCE showed a good linearrelationship to DA with a concentration range of 2.0～250μmol/L and a detection limit of 0.67μmol/L.In addition,the prepared AuNPs/MXene/GCE have good stability and selectivity.Finally,the sensorcan sensitively detect the content of DA in medical dopamine hydrochloride injection.4.A simple and extensible self-assembly method was used to prepare MXene-CNTs sensing materials with good conductivity.The morphology and composition of MXene-CNTs were characterized by SEM,XRD and X-photoelectron spectroscopy（XPS）.Due to the fine assembly and synergy between 1D CNTs and 2D MXene nanosheets,MXene-CNTs have excellent electrical conductivity.At the same time,the addition of CNTs effectively inhibited the disordered stacking of MXene nanosheets,provided a rich space position forthe adsorption of IAA molecules,and promoted the electron transferrate.The composite material was furtherused to modify the screen-printing electrode（SPE）,which showed good electrochemical response to IAA.The detection range of the electrochemical sensorforIAA was 0.05～125μmol/L,and the detection limit was 16.7 nmol/L.This sensorcan be used forthe determination of IAA in pea seedlings with satisfactory results.