Construction And Performance Study Of Anti-Interference Photoelectrochemical Biosensors

With rapid development of social technology,the researches of various diseases are penetrating deeply,and many disease markers are practically used in life analysis and detection.In order to improve the efficiency of detection and clinical diagnosis of diseases or cancers,the constructed biosensing platform must detect the relevant disease markers rapidly,sensitively and accurately.Photoelectrochemical analysis method is a new detection technology deriving from classical electrochemical method.With the advantages of simple device,rapid respondence and low price,it has been widely used in lifehealth analysis,environmental safety detection,and other fields.In photoelectrochemical analysis,light was used as the excitation signal and electricity was the response signal.The energy takes a different form,which effectively reduces the background signal of biosensor,making photoelectrochemical technology a new analytical method with wide application potential.However,the disease biomarkers in complex biological fluid（serum,saliva,urine,etc.）or internal circulation environment is usually lower than that of a large number of coexisting background substances,which will be nonspecifically adsorb on the electrode surface and reduce the sensitivity and specificity of the biosensor,even result in false positive or negative signals.Therefore,based on the antifouling materials and constructionstrategies of biosensors,several antifouling photoelectrochemical sensing platforms were developed in this thesis,including immunosensor,DNA biosensor and cytosensor.The main contents are as follows:（1）A novel antifouling photoelectrochemical immunosensor for the sensitive and specific detection of cardiac troponin（c Tn I）was constructed based on photocathodic material with high photocurrent output and zwitterionic peptide with excellent antifouling performance.The Au/ZIS/CIS ternary heterojunction was used as the photocathode,and the capture antibody Ab and zwitterionic peptide were immobilized through Au-NH₂ and Au-S bonds,respectively.The zwitterionic peptide KAEAKAEAPPPPC was electroneutral and hydrophilic,which could form a solid antifouling interface to block the active sites and hinder the non-specific adsorption of macromolecular proteins effectively.In addition,the photocathode has better antifouling ability to reducing substances than the photoanode because of the reduction of electrons at the photocathode interface,so the prepared biosensor could effectively alleviate the nonspecific adsorption and improve the sensitivity and selectivity,which provided a practical and feasible method for real biological sample detection.（2）By separating photoelectrode from biological recognition and using the signal cascade amplification strategy,a novel anti-interference photoelectrochemical DNA biosensor was constructed based on the advantages and great application potential of the anodic aluminum oxide（AAO）nanochannel in the photoelectrochemical analysis sensing.Taking human T-cell virus type I（HTLV-I）as the target,CN/Ti O₂photoelectrode was prepared to ensure the stable and obvious photocurrent response of the system.The biological recognition and signal cascade amplification were carried out in AAO nanopores.The separation of the optical electrode and the biometric part could reduce the negative impact of the photoelectrode incubating in biological samples,and effectively improve the selectivity and antifouling ability of the sensor.In addition,the detection performance of the biosensor was further improved through the exonucleas III cyclic target amplification strategy and plugging effect of Ag@Au nanoparticles on nanoporous channels.The prepared sensing platform had low detection of limit and a wide linear detection range.（3）Based on zwitterionic peptides with great antifouling property in complex biological samples,an antifouling photoelectrochemical cytosensor was developed to detect human breast cancer cells（MCF-7）.The photoelectrode of the Cd S/Cu In S₂sensitized structure could not only obtain a high and stable cathodic photocurrent signal response,but also anchored MCF-7 aptamer and zwitterionic peptide on the substrate.Through the specific recognition reaction between the aptamer and the target,large steric hindrance was formed and the connection between the response of the sensing signal and the concentration of MCF-7 was established,which can further achieve the detection of MCF-7.Based on the anti-reducing ability of p-type semiconductor,the cytosensor also introduced a zwitterionic peptide KQEQKQEQ PPPPC with excellent antifouling effect to form a hydration layer,which can effectively prevent the adhesion of non-specific proteins on the electrode surface and improve the sensitivity and specificity of the sensor.This sensor construction strategy makes it possible to detect cancer cells in complex biological samples accurately.