Construction And Application Of Carbon Based Electrochemical Sensor For The Detection Of Ascorbic Acid,Dopamine And Uric Acid

The normal physiological functions of organisms are closely related to the small molecules which are coexistenced in our body such as ascorbic acid(AA),and dopamine(DA)and uric acid(UA).So it is very important to detect the content of these three substances in the body.Among the detection methods,electrochemical detector has been widely used in the analysis and detection of AA,DA and UA,for the advantages of low cost,high selectivity,simple operation and fast response and so on.In this study,three kinds of electrochemical sensors were constructed on the basis of single walled carbon nanotubes and three-dimensional graphene hydrogel.Firstly,synthesis the quantum dots and noble metal nanomaterials through a simple method and combine with the SWCNTs and 3DGH,respectively.Secondly,the physical properties of composites materials were systematically characterized using SEM,TEM,UV–vis,XRD and EDX.The electrochemical performance of the biosensor was thoroughly investigated by cyclic voltammetry,differential pulse voltammetry and electrochemical impedance spectroscopy.Finally,the composite modified electrode was applied to the detection of ascorbic acid,dopamine and uric acid,and the the specific research contents are as follows:(1)Gold nanoparticles(AuNPs)and carbon quantum dots(CQDs)were prepared by the reference method.The rapid and sensitive detection of dopamine and uric acid was achieved through excellent electrocatalytic activity of CQDs and the good conductivity of AuNPs and SWCNTs.The concentrations of dopamine and uric acid showed a good linear relationship in the range of 4.0 ?M to 100.0 ?M and 4.0 ?M to 70.0 ?M,and the detection limits were 0.089 ?M and 0.125 ?M(S/N=3),respectively.The prepared CQDs-AuNPs/SWCNTs/GCE electrochemical sensor has a good application value in the actual serum samples.(2)Three-dimensional graphene hydrogel were prepared under the condition of 180? through one step hydrothermal method.A novel selective 3DGH-Fc/GC E sensor was constructed for the simultaneous detection of ascorbic acid,dopamine and uric acid.The detection range of the three substances were 20~450 ?M(AA),10~180 ?M(DA)and 8~400 ?M(UA)and detection limits were 0.183 ?M(AA),0.042 ?M(DA),0.067 ?M(UA)(S/N=3),respectively.Compared with the graphene based electrochemical sensors reported in the literature,this 3DGH-Fc/GCE electrochemical sensor has fast response and high sensitivity.(3)3DGH-AuNPs/GCE electrochemical sensor was constructed and used to detect ascorbic acid,dopamine and uric acid.CV,DPV and i-t were taken to study on the electrochemical behavior of 3DGH-AuNPs/GCE.The linear ranges of ascorbic acid,dopamine and uric acid were 1.0~700.0 ?M(AA),0.2~30.0 ?M(DA)and 1.0~60.0 ?M(UA),and the detection limits were 0.028 ?M(AA),0.0026 ?M(DA),0.005 ?M(UA)(S/N=3),respectively.The developed electrochemical sensor has a good recovery in the actual serum samples,which provides a new method for the rapid and accurate detection of ascorbic acid,dopamine and uric acid in real samples.