The Investigation Of Electrochemical Probe Based On Phenothiazine Derivatives Applied In Electrochemical Immunosensor

Electrochemical immunosensors are widely used for the quantitative detection of cancer tumor markers because of their high sensitivity,good selectivity,low cost and simple and convenient operation.In this thesis,electrochemical probes of are prepared phenothiazine derivatives as antibody markers,combined with various sensor construction strategies,an electrochemical immunosensor for quantitative analysis of tumor markers was developed.This paper mainly includes the following four parts:The first part,a dual-mode electrochemical immunosensor for sensitive detection of Aβwas successfully fabricated,which based on amperometric i-t（i-t）and square wave voltammetry（SWV）.The immunosensor used Cu-Al₂O₃-g-C₃N₄-Pd as the matrix material and UiO-66@PANI-MB as the signal probe.Cu-Al₂O₃-g-C₃N₄ has a good catalytic reduction performance of H₂O₂.In order to enhance the biocompatibility of the material,Pd NPs was introduced to improve the immobilization rate of antibodies.At the same time,the synergistic effect of Cu-Al₂O₃-g-C₃N₄ and Pd NPs further improved the catalytic activity of H₂O₂.In addition,UiO-66 with high porosity and large specific surface area was used as the carrier of methylene blue（MB）,which could be used as an electrochemical probe by electrostatic adsorption of MB.The electrochemical immunosensor for dual-mode measurement not only improves the detection efficiency and accuracy,but also reduces errors,enhances its analytical performance and clinical reliability.Under the best experimental conditions,the dual-mode electrochemical immunosensor showed good analytical performance in the linear range of 10fg/m L-100 ng/m L,and the detection limit was 3.3 fg/m L（S/N=3）,This mode provided a new way for the sensitive detection of other tumor markers.The second part,a dual-mode electrochemical immunosensor for quantitative detection of CYFRA21-1 was successfully fabricated,which based on amperometric i-t（i-t）and differential pulse voltammetry（DPV）.The immunosensor used Co Se₂-GO-Au as the matrix material and poly（MB）-Au as the electrochemical probe.Co Se₂ nanomaterials had strong catalytic activity of H₂O_2,and also had the disadvantages of poor conductivity and easy agglomeration.Graphene oxide（GO）was introduced to disperse the Co Se₂ material and enhance the conductivity of the material.At the same time,the introduction of Au nanoparticles also improved the conductivity of the material and increased the binding rate of the material to the antibody.In addition,using the noble metal polymer poly（MB）-Au as the electrochemical probe,which not only had a strong electrochemical signal but also had good biocompatibility.Under the best experimental conditions,the dual-mode electrochemical immunosensor not only improved the accuracy of detection but also enhanced the analysis performance of the immunosensor.In the range of 1 pg/m L to 100 ng/m L,the detection limit of the immunosensor was 0.24 pg/m L（S/N=3）,which provided a wider detection range and lower detection limit for the detection of CYFRA21-1.The third part,a ratiometric electrochemical immunosensor was manufactured to quantitative detection procalcitonin（PCT）by DPV.We selected Fc-COOH and TB with good electrochemical signals as the electrochemical signal probes.Si O₂ and UiO-66 with large specific surface area was used as the platform,which could carry a large number of Fc-COOH and TB probes to achieve the purpose of enhancing the electrochemical signal.The key to the ratio electrochemical immunosensor was that Si O₂-Fc-COOH-Au and UiO-66-TB could generate electrochemical signals at different potentials.Under the best conditions,a wide detection range from 1 pg/m L to 100 ng/m L and a lower limit of detection（LOD）were obtained,with a detection limit of 0.3 pg/m L（S/N=3）.The novel strategy of the immunosensor provided strong support for the quantitative analysis of PCT,and also provided a way for the analysis of other markers.The fourth part,ppy-Au was used as the matrix material and Cu-MOFs-Au-TB was used as the electrochemical probe to construct a sandwich electrochemical immunosensor to realize the sensitive detection of specific enolization of neurons enzymes（NSE）.Because ppy-Au material had strong electrical conductivity and good biocompatibility,it could provide a platform for a large amount of antibody loading.In addition,Cu-MOFs-Au had a large specific surface area and good conductivity,which could be combined with TB as an electrochemical probe through electrostatic adsorption,providing excellent electrochemical signals for immunosensors.The traditional sandwich-type model was used to construct an electrochemical immunosensor.Under the best experimental conditions,the sandwich-type electrochemical immunosensor had a lower limit of detection（LOD）from 0.1 pg/m L to 100 ng/m L and the detection limit was 0.032 pg/m L（S/N=3）,which provided a guarantee for the quantitative detection of NSE.