Construction And Application Of Bipolar Electrode Electrochemiluminescence Paper Chip Sensor

At present,there are still many malignant diseases threatening human life in the world,and some of them even develop into cancer.Accurate detection of different tumor markers is very important for the treatment of cancer.As a class of endogenous non-coding RNA,microRNA participates in many functions of the body,and is used in several biological processes,such as differentiation,metabolic homeostasis,apoptosis and proliferation.The presence of miRNAs in body fluid may be associated with cancer（prostate,breast,colon,lung,etc.）or other diseases（diabetes,heart disease,etc.）,which makes them a new biomarker.Therefore,the detection of miRNA is of great significance in disease diagnosis and miRNA function research.BPE-ECL biosensor can play an important role in disease detection.The detection principle is that when a certain direct current voltage is applied to the system with chemiluminescent substances,a chemical reaction will occur between the products on the electrode surface or between the electrode products and other co-existing substances in the system,resulting in chemiluminescence behavior;or the chemiluminescence is generated by the decomposition of unstable intermediate transition substances after the redox reaction directly on the electrode surface.At the same time,the combination of ECL technology and bipolar electrode can greatly reduce the interference signal,which makes it more sensitive than traditional electrochemical methods.Based on its principle,biosensors are used to track and detect disease-related biomarkers in human body sensitively.At present,many factors that affect the performance of the sensor are the design of bipolar paper chip and signal amplification strategy,reasonable paper chip partition and effective signal amplification strategy are helpful to improve the detection performance of the sensor.In BPE-ECL paper chip sensors,paper chips as sensing substrate materials have the advantages of easy patterning,low cost,portability and good biocompatibility.Combined with effective signal amplification strategy,the detection sensitivity of BPE-ECL biosensor is greatly improved.Based on these properties,bipolar paper chip sensing platform and effective ECL signal amplification strategy have great application value in the construction of biosensors.Based on the ECL analysis on the BPE,this paper is dedicated to the research of signal amplification,method optimization,and paper chip design.The following aspects are specifically carried out.（1）The paper-based electrochemiluminescence sensor platform with closed Au bipolar electrodes detects miRNA-155In this study,a paper-based closed Au-bipolar electrode electrochemiluminescence biosensing system was constructed for the rapid and sensitive detection of miRNA-155 The microfluidic paper sensing platform is constructed by wax printing technology,screen printing method and in-situ growth of Au nanoparticles（NPs）to form hydrophilic units,hydrophobic boundaries,waterproof electronic bridges,driving electrode areas and bipolar electrode areas.For rapid and sensitive detection,the prepared DNA（S1）-Au Pd NPs were used to modify the cathode of the bipolar electrode by hybrid chain reaction.The target can start multiple cycles to load more Au Pd NPs to catalyze the reduction of H₂O₂.The classic Ru（bpy）₃²⁺/TPr A luminescence system was used in the reporting unit.Due to the charge balance between the anode and the cathode in the BPE sensing system,there was a quantitative relationship between the intensity of ECL and the concentration of miRNA-155 and a high sensitivity detection of the biomarker miRNA-155 was realized.（2）Paper-based electrochemiluminescence bipolar electrode for the detection of miRNAsIn this work,a new type of potential-resolving paper-based biosensor based on bipolar electrode electrochemiluminescence strategy was constructed for simultaneous detection of multiple miRNAs.Cd Te QDs-H2 and Au@g-C₃N₄ NSs-DNA1 were used as dual electrochemiluminescence signal probes,and carboxylated Fe₃O₄ magnetic nanoparticles were used as carriers.Cd Te QDs-H2/S₂O₈^2-and Au@g-C₃N₄ NSs/S₂O₈^2-respectively exhibitd two strong and stable ECL emission under their appropriate driving voltage.Combining the three-dimensional DNA nanomachine model at the same time,the cycle of the target miRNA was realized and the electrochemiluminescence signal in the sensing system was greatly amplified.The combination of the bipolar electrode system and the potential-resolving electrochemiluminescence method can avoid the mutual interference between the electrolyte solutions and realize the accuracy of the output signal.Finally,the prepared ECL biosensor has a good linear ECL response to miRNA-155 and miRNA-126.