The Electrode Modified With Carbon Materials And Its Application In Biosensors

Electrochemical biosensors have the advantages of high detection sensitivity,low detection limit,wide detection concentration range,simple and easy operation,and miniaturization of equipment.They play increasingly important roles in the fields of medicine,food and environment.In recent years,researchers have continuously strived to further improve the detection performance of electrochemical biosensors and expand their application range.However,there is still a lot of room for improvement in many aspects of the electrochemical biosensors.In this work,a lot of work has been carried out around improving electrode performance,simplifying detection steps,improving detection sensitivity and other aspects.Firstly,the Au-rGO/FTO electrode was prepared by one-step electrodeposition in the second chapter.The characterization of the electrode morphology showed that the graphene on the electrode formed the three-dimensional network structure,and the small-sized gold rice particles were uniformly distributed on the surface of the graphene.This structure provided more efficient paths for electron transfer and allowed the gold nanoparticles to exhibit higher catalytic activity.The electroactive surface area,active site number and catalytic rate constant of the electrode were calculated by electrochemical method,and the structure-activity relationship of the electrode was explained.In order to detect the performance of 3D Au-rGO/FTO,the electrode was used to simultaneously detect nitrite and hydrogen peroxide.Considering that the thiol-modified DNA could be conveniently immobilized on the surface of the 3D Au-rGO/FTO by the Au-S bond between AuNPs and sulfhydryl groups,and Au-rGO/FTO could provide a large number of active sites for DNA loading and it had good electron transfer ability.Therefore,the 3D Au-rGO/FTO electrode prepared in Chapter 2 was used in Chapter 3,and the probe DNA was loaded on the surface of the electrode through the Au-S bond to explore its application in DNA detection.During the detection,we directly immersed the electrode hybridized with the target DNA(mutant p53 gene)in methylene blue(MB)for detection,which removed the adsorption process of MB on the electrode surface.This simplified the steps of DNA detection,and the detection sensitivity and the anti-interference ability were analyzed in detail.Since 3D Au-rGO/FTO electrode could load DNA well and had good electrochemical performance,the aptamer sensor based on 3D Au-rGO/FTO electrode was used in the Chapter 4 for the detection of thrombin.In the experiment,the aptamer(TAB I)was immobilized on the surface of the 3D Au-rGO/FTO electrode by Au-S bond,and incubated under appropriate conditions to form the "Sandwich" structure of aptamer(TAB I)-thrombin-aptamer(TAB II).In the assay,the electrocatalytic action of MB on the nano-gold particles modified by TAB II produces an electrical sianal for determining the concentration of thrombin.In the assay,the electrocatalytic action of the TAB II-modified nano gold particles on MB produced an electrical signal for determining the concentration of thrombin.The aptamer sensor could sensitively detect the concentration of thrombin by analysis which further proved that 3D Au-rGO/FTO did have excellent electrochemical properties.In summary,3D Au-rGO/FTO electrode with high electrochemical activity was prepared by one-step electrochemical deposition in this paper.The electrode was used to simultaneously detect nitrite and hydrogen peroxide,and the application of the electrode in DNA sensor was explored.Finally,an aptamer sensor was constructed using this electrode for thrombin detection.The experimental results showed that the 3D Au-rGO/FTO achieveD good detection of the targets in different electrochemical sensors.