Construction Of Closed Bipolar Electrode-Electrochemiluminescent Biosensor For PSA Detection

Over the past two decades,bipolar electrode(BPE)has been adopted to be an effective tool for chemical and biological analysis,materials synthesis,and catalysts screening.In the field of chemical and biological analysis and catalyst screening,BPE is usually combined with electrochemiluminescence(ECL),electrochromism,and electrofluorescence,as signal readout.Among these approaches,ECL is the commonly used technique due to its overwhelming advantages,such as low background interference,simple operation process,high throughput,and visual imaging capability.The electrochemical signal on the bipolar electrode can be adjusted by modifying the cathode and anode.Thus,the application scope and detection scope of ECL are expanded,which is a very important improvement for the application of ECL in the field of biological analysis.With the development of society and the progress of medical treatment,tumor markers have become an important basis for the diagnosis of cancer and many other diseases.The tumor markers can be detected conveniently,concisely and accurately,which is of great significance for the early detection and treatment of patients’ cancer.With the development of BPE-ECL technology,it is possible to apply it to the detection of prostate-specific antigen(PSA).Therefore,this paper aims to design a new detection platform to detect PSA with low production cost,simple application method,high sensitivity and low detection limit.According to the above research status and existing theoretical basis,this paper has carried out specific work on the following two aspects:1.Construction of Janus bipolar electrode and the study of its electrodeposition mechanismThe experiment uses graphite paper with high conductivity and low cost as a conductor,which can be cut into any shape.Graphite paper(GP)was used as BPE and covered by two layers of PDMS slices with reservoirs to construct closed bipolar electrode device.By using bipolar electrodeposition technology to plate gold on one end of the graphite paper,and then change the direction of the electric field to plate gold on the other end of the graphite paper.In this way,the surface characteristics at both ends of the bipolar electrode can be effectively regulated by an electrochemical process.It was found that although the gold can be successfully plated in this step in the experiment,the gold deposited for the first time will dissolve and disappear.In order to study the mechanism,we added different solution in the reservoirs and applied constant and linear scanning voltammetry(LSV)on the driving electrodes.The whole process was recorded by camera.The results show that the disappearance of the first gold film is closely related to the conductivity of the solution and the reaction on the driving electrode.Then,we determined the appropriate voltage and solution composition to construct the Janus bipolar electrode and successfully constructed a closed bipolar electrode with gold-plated ends.2.Detection of prostate specific antigen(PSA)with bipolar electrodesThe PSA sensor interface was constructed at one end of the Janus bipolar electrode(both ends are gold-plated).A sandwich structure was formed on electrode surface between primary antibody,PSA,and SiO2 nanoparticles labeled secondary antibody.By such a recognition process,the resistance at this end increased dramatically,leading to the quenching of ECL signal.In order to amplify the change of ECL signal,we added hydrogen peroxide to the other end of the bipolar electrode which could amplify the ECL signal by promoting the reduction reaction of hydrogen peroxide through the gold film.In addition,we also characterized the impedance and ECL of the PSA assembly process,and optimized the concentration of the luminous solution and the concentration of H2O2.We successfully built a biosensor to detect PSA.The detection of PSA showed a linear relationship between ECL signal and PSA concentration in the experiment.A good linear relationship caould be observed between ECL intensity and PSA concentration in the range of 1×10-6-1×10-11 g/mL.The linear equation lg IECL=-0.04221gC(g/mL)+5.865,R2=0.9936.The anti-interference experiments of thrombin,AFP and BSA showed that the biosensor had good specificsity and anti-interference ability.