Nano-functional Interface Assembly And Their Application In Photoelectrochemical Analysis

Photoelectrochemical technology,a recently emerged and fast-growing analytical method derived from electrochemistry,inherits attractive merits from the traditional electrochemical methods.The photoelectrochemistry is simpler,cheaper,and easier to miniaturize than that of the traditionally optical detections.The different forms of energy for excitation?light?and detection?electricity?effectively reduces background noise,offering its potentially high sensitivity.As a result,Therefore,researchers began to combine photoelectrochemical technology with biological detection,resulting in photoelectrochemical?PEC?bioanalysis technology.PEC bioanalytical technology are now receiving increasingly considerable interest due to their excellent performance in various fields.The common PEC bioanalytical techniques are mainly used for enzyme detection,immunoassay,DNA detection,biological small molecule detection,and so on.In this paper,two kinds of simple-synthesised photoactivity materials were used to establish immobilized and split-type PEC biosensors for glucose,carcinoembryonic antigen?CEA?,vascular endothelial growth factor?VEGF?,and alkaline phosphatase?ALP?detection by using different PEC methodologies.The major contents are described as follows:1.PEC immunosensor by means of glucose oxidaseIn this chapter,we induce a novel strategy for the construction of cathodic PEC immunoassay on the basis of enzymatic reaction inhibited exciton trapping for PbS quantum dots?QDs?.The cathodic photocurrent of the PbS QDs sensitized NiO was inhibited by cupric ions due to the formation of exciton trapping centers of CuS on their surface.In the presence the model target of carcinoembryonic antigen?CEA?,a immunoreaction occurred with the detection antibody labeled glucose oxidase?GOx?as the signal tracer.The enzymatic reduction of ferricyanide([Fe?CN?₆]^3-)by GOx produced ferrocyanide([Fe?CN?₆]^4-),which easily combined with cupric ions to form Cu₂[Fe?CN?₆]?CuHCF?aggregates,and thus interrupted the formation of the exciton trapping centers of CuS.The detection of glucose and CEA was achieved.The PEC immunosensor shows high specificity and good reproducibility of the target protein.2.PEC sensor for detecting VEGFThis chapter uses doxorubicin?Dox?as an electron acceptor,accepting electrons from PbS QDs,resulting in an increase in cathodal photocurrent of PbS QDs.The more Dox,the greater the photocurrent.Based on which,we establish a simple,efficient and rapid detection of VEGF biosensors.VEGF can be connected to dsDNA through a specific base recognition site on double-stranded DNA?dsDNA?.Dox can also be embedded into dsDNA because of its own characteristics.As a bridge,it realizes the close-range electron transfer between PbS QDs and Dox from ds DNA fixed on PbS QDs,which could establish highly sensitive detection of VEGF.3.Split-type PEC sensorIn this chapter,a novel and general strategy of split-type immunoassay is developed based on redox chemical reaction modulated photoelectrochemistry of carbon dots?CDs?.Specifically,the photocurrent of the CDs sensitized titanium dioxide nanoparticles?TiO₂ NPs?electrode was inhibited obviously by KMnO₄ due to the oxidation of surface hydroxyl groups of CDs to electron accepting carbonyls.While the inhibited photocurrent of the KMn O₄treated electrode can be restored by ascorbic acid?AA?because of the regeneration of electron donating hydroxyls to promote electron-hole separation.Take carcinoembryonic antigen?CEA?as a model analyte and alkaline phosphate?ALP?as a catalytic label tracer to hydrolyze ascorbic acid 2-phosphate?AAP?for producing AA,which greatly stimulated the photocurrent of the transducer of KMnO₄ treated photoelectrode for signal output.This redox chemical reaction modulated PEC strategy enabled the separation of the immunoreaction from the photoelectrode?that is,a split-type PEC detection?,eliminating potential damage of biomolecules during the PEC detection processes and leading to enhanced throughput detection as compared to conventional PEC configurations.