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Study On Preparation Of Poly (Thionine)/ITO Photoelectrode And Application In Analytical Chemistry

Posted on:2012-10-15Degree:MasterType:Thesis
Country:ChinaCandidate:J YuFull Text:PDF
GTID:2321330491463912Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
The photoelectrochemical analysis is a new analytical method by the use of photoelectrochemical effect.In the method,the light excites a photoelectrically active species to bring a photoelectrochemical reaction.The molecule participated in reaction could be determined by direct or indirect detection of the photocurrent.The excitation and detection of photoelectrochemical method is completed step by step.In relation to the photometric method,it has advantages of the simple equipment,low cost,easy miniaturization and integration.In relation to the electrochemical method,the generation of photocurrent is similar to photocatalytic principle,its sensitivity is higher than general electrochemistry,could be comparable with the electrochemiluminescene.Photoinduced analytical methods are generally by means of photosensitive electrode,it is prepared by a material with photoelectric activity.In the paper,a new photoelectrochemical sensing platform for H2O2 was fabricated by electropolymeri-zation of thionine on ITO electrode.This photosensitive interface was employed as an electron acceptor,and H2O2 proceed from enzymatic catalysis was employed as an electron donor.Because H2O2 is an intermediate of enzyme-catalyzed reaction,the catalytic activity of protein and its substrate could be determined indirectly by measuring of photocurrent produced in the enzymatic reaction.On the basis of this photosensitive interface,the main works are shown as follows:1.Thionine,a material with photoelectric activity,was electropolymerized on the surface of ITO electrode.The photocurrent was generated from the reaction between the photosensitive interface and H2O2 which was employed as an electron donor.In the paper,the effects of bias voltage and pH of electrolyte were investigated.And the photoelectrochemical response mechanism of poly?thionine?on ITO electrode to H2O2 was described.2.The determination for catalytic activity of glucose oxidase was based on the photocurrent generated from the photoelectrochemical reaction between the photoelectrochemical sensing interface and H2O2 which is the product of catalyzing glucose by protein.In the paper,the photoelectrochemical response of poly?thionine?immobilized on ITO electrode to H2O2 was described.The effects of bias voltage,pH of electrolyte and concentration of substrate to the photoelectrochemical response were investigated.The feasibility of method was acknowledged through monitoring the catalytic activity of glucose oxidase.The present method is an economical,speedy,simple and convenient technique to detect the catalytic activity of protein without hydrogen peroxidase.3.On the basis of photoelectrochemical effect between the photosensitive interface and H2O2,a new glucose biosensor was prepared by using chitosan to immbolize glucose oxidase on photoelectrode.The optimized condition for the response of the biosenser,such as enzyme loading 35?L?49.2mg·ml-1,122U·mg-1?,bias voltage?0.50V?,the concertration of chitosan?0.3%?,pH of electrolyte?pH5.5?were selected.The linear response of glucose concentrations from 5.00?400x10-5mol·L-1?was obtained with a detection limit of 0.2 mmol·L-1.The stability of the biosensor was better;no apparent change was found when it was stored at 4?.4.A photoelectrochemical choline biosensor was fabricated by using chitosan and glutaraldehyde to covalently attach choline oxidase on photoelectrode.In the paper,photoelectrochemical responses of biosensor to choline was studied.The effects of bias voltage?0.50V?,enzyme loading 5?L?1.5mg·ml-,12U·mg-1?and pH of electrolyte?pH6.5?to photocurrent were investigated.Under the optimized conditions,the linear response of choline concentrations ranged from 0.05 to 2.00 mmol·L-1 with a detection limit of 30.0 ?mol·L-1?and sensitivity of 65.7 nA-mmol·L-1.The applied feasibility of biosensor was acknowledged through monitoring the phosphatidylcholine in lecithin samples.The prepared biosensor is economical,speedy,simple and convenient to detect the choline without hydrogen peroxidase.
Keywords/Search Tags:poly(thionine), hydrogen peroxide, photoelectrochemistry, glucose oxidase, glucose biosensor, choline biosensor
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