| Photoelectrochemical?PEC?assay,which possesses the advantage of low background,remarkable sensitivity,simple instrument and easy miniaturization because it combines the advantages of optical and electrochemical method,is a rapidly developed and promising analytical method.Thus,PEC assay has been widely used in various analytical field,such as environmental chemistry,analytical chemistry and biomedical fields.The detection principle of the PEC sensor is to determine the changing of electrical signal caused by the biological recognition between the identification element and the target molecule based on the used material with photoelectric conversion properties under photoexcitation.WO3 is an n-type semiconductor with unique photoelectric and physicochemical property.In this paper,the photoelectrochemical properties of WO3 nanomaterials on the electrode were studied.Based on the excellent photoelectrochemical properties of WO3 nanomaterials,novel photoelectrochemical sensors for high sensitive and fast detection of glutathione?GSH?and lung cancer marker CYFRA 21-1 have been developed.This study not only extends the application of WO3 nanomaterial in photoelectrochemical biosensors,but also provides a good theoretical basis for the construction of photoelectrochemical sensors based on the other nanomaterials.The main contents of this study include the following two chapters:Chapter one:In the first part of this chapter,we have made a systematic study on the feasibility of constructing photoelectrochemical sensors based on WO3 nanomaterials.At the same time,the morphology and the photocatalytic performance of WO3/ITO electrode have been investigated.The experimental results showed that the linear response to detect GSH ranges from1.0×10-7 molˇL-1 to 1.0×10-3 molˇL-1,the detection limit was 2.5×10-8 molˇL-1.However,the selectivity of the sensor is not satisfied.Therefore,MnO2 nanosheets have been introduced to form MnO2-WO3 composites on the basis of the above studies,and a high selective and sensitive sensor for the detection of GSH has been constructed because GSH can selectively react with MnO2 nanosheets in the acidic conditions.The results showed that the MnO2-WO3 composite material modified ITO electrode increased the detection performance of GSH,and the detection range was expanded with the concentration from 1.0×10-52.0×10-33 molˇL-11 and 2.0×10-35.5×10-22 molˇL-1,and the detection limit was 1.0×10-66 molˇL-1.Thus,the presented method has a wider detection range and significantly improves the selectivity of the PEC sensor,and it's expected to be used for the detection of complex actual samples.Chapter two:In order to further expand the application of WO3/ITO photoelectrochemical sensing plateform,the dopamine self-polymerization on the WO3/ITO electrode surface to form a hydrophilic polydopamine?pDA?polymer film was developed to further self-assembly the biomolecules.This process is facile,green and easy to operate and does not require the addition of organic solvents.Based on the strong viscosity and excellent self-assemble property of the pDA of the pDA-WO3/ITO,CYFRA 21-1 antibody was modified on the surface of electrode in the absence of other couple-linking agent.Thus,a novel photoelectrochemical immnuosensor has been constructed.The introduction of pDA polymer film has the advantages:?1?the transfer rate of electrons in pDA-WO3 composites has been greatly improved so that the photocurrent of pDA-WO3/ITO electrode was enhanced;?2?due to the good biocompatibility of pDA,the presented pDA-WO3/ITO biosensor interface can well maintain the biological activity of immobilized antibodies.Under the optimization conditions,the detected photocurrent signal had a good linear relationship with the concentration of CYFRA 21-1 in the range of 5.0 ngˇmL-175.0 ngˇmL-1,the detection limit was 1.64 ngˇmL-1.The experiment results showed that the proposed PEC biosensor based on pDA-WO3/ITO has been successfully achieved a sensitive and quantitative determination of lung cancer markers. |
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