Modified Electrodes For The Simultaneous Determination Of DA, AA And UA Based On Functional Carbon Nanotubes And Mesoporous Silica

DA,AA and UA are crucial small biomolecules in human body.Unnatural levels of these species will contribute to various diseases.For example,insufficient level of DA may lead to Parkinson's and Alzheimer's disease,deficiency of AA may lead to scurvy,and metabolism disorder of UA may lead to gout.Determination of AA,DA,and UA is important for making diagnoses and taking precautions against diseases.However,as the oxidation potentials of these species are very close,modifide electrodes was applied to the detection of these biological molecules.In order to realize the simultaneous determination of them,in this paper,three kinds of modified electrodes was prepared,and the electrochemical response was studied by cyclic voltammograms(CV)and differential pulse voltammetric(DPV)technique:1.Polymeric ionic liquid was modified on MWCNTs by non-covalent modification,non-dispersible MWCNTs can be dispersed,and the excellent characteristics of MWCNTs can be retained.The introduction of Polymeric ionic liquid can increase the electron transfer rate.So,Polymeric ionic liquid(Poly(ViEtIm~+Br~-))and MWCNTs was combined,and Poly(ViEtIm~+Br~-)/MWCNTs/GCE was prepared by using the compound.On Poly(ViEtIm~+Br~-)/MWCNTs/GCE,the synthesized Poly(ViEtIm~+Br~-)/MWCNTs were characterized by FT-IR and TEM.Poly(ViEtIm~+Br~-)and MWCNTs has been formed and it was well-dispersed in water.In pH=7.4 PBS,the linear response range for AA,DA and UA are 40-5000 ?M,2-180 ?M and 4-50 ?M,respectively.And it was applied to the determination of AA and DA in vitamin C injection and dopamine hydrochloride injection.2.Mesoporous silica(MCF)have the mesoporous material properties,such as large specific surface area,pore diameter size adjustable.Moreover,the interlinked 3D porous structure can improve the transfer and diffusion of substance in its pore canal.Duo to these properties,modified carbon paste electrode(MCF/CPE)were prepared by using the mixture of graphite and MCF.On MCF/CPE,in pH=6 PBS,realized the simultaneous detection of UA and DA in the presence of AA,and the linear response range for DA and UA are 2-220 ?M and 1-120 ?M,respectively.3.MCF-IL have been synthesized by the introduction of ionic liquid(IL)on MCF.And MCF-IL/CPE was prepared by adding the dopant of ionic liquid functionalized MCF(MCF-IL)into the carbon paste.On MCF-IL(17%)/CPE,in pH=6 PBS,realized the simultaneous detection of UA and DA in the presence of AA,and the linear response range for DA and UA are 5-160 ?M and 1-160 ?M,respectively.On MCF-IL(25%)/CPE,in pH=6 PBS,realized the simultaneous detection of AA,UA and DA,and the linear response range for AA,DA and UA are 50-3000?M ?M,2-180?M ?M and 1-150?M,respectively.And it was applied to the determination of AA and DA in samples.