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New Type Of Alkyl Phenol Estrogen Bpa Electrochemical Biosensor Research

Posted on:2013-02-05Degree:MasterType:Thesis
Country:ChinaCandidate:T M YaoFull Text:PDF
GTID:2248330374977477Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Enzyme biosensor is an important means of analysis and detectionof biological substances or other toxic substances using the highlyspecific biological recognition process between the enzyme activitysites and the target analyte. to achieve quickly recognize anddetection of the targets. Effective enzyme biological sensor system canbe applied in food industry, environment monitoring and clinicalmedicine, and other research fields. Therefore, it is very important thatthe preparation of a fast, simple, sensitive enzyme biosensor to achievereal-time monitoring and.Bisphenol A is widespread in all aspects of our daily life, and brings abad influence on the human reproductive system, cranial nerve systemand immune system after human contact with it. The detection forbisphenol A has attracted general publics’ attention. Bisphenol A canbe measured sensitively, rapidly and accurately using tyrosinase sensorsmodified by different material.In this paper, we combined new nanometer material with enzyme(tyrosinase), and then applied them in building electrochemicalbiosensors. The ideas for the research were described as following:(1)Using the specific response of tyrosinase to bisphenol, we fabricate aenzyme biosensor with a good selectivity and large response signal,(2).studies on the application and efficiency of the enzyme biosensorconsisted of Au-Ni and other materials in the preparation ofelectrochemical biosensors. With this in mind, the works in the presenthave been carried out:(1) A new Au-Ni composite material was synthesized andcharacterized by XRD. This composite material can be modified on theelectrode surface through the bonding effect of chitosan to prepare anew electrochemical sensor. The electrochemical characteristics of the sensor were characterized by various electrochemical method s suchas cyclic voltammetry, ac impedance method, amperometric i-tcurve, etc. The sensor showed a good amperometric response for theglucose. The current response of the sensor increases linearly with theconcentration of glucose from2.5×10-5to9.5×10-4mol/L with arelative coefficient of0.9950. The detection limit (3σ) is1×10-5mol/L.The sensor shows a fast response,high sensitivity, good stability to thetarget and ability of anti-interference for some common substancessuch as uric acid and ascorbic acid.(2) A bisphenol A (BPA) biosensor was fabricated by immobilizingtyrosinase using a NHS-EDC method on the surface of glassy carbonelectrode (GCE) modified with composite material of Au-Ni andchitosan. Tyrosinase immobilized on the surface of the electrode byNHS-EDC method can retain its bioactivity. The composite?lmpossessed excellent inherent conductivity can enhance the electrontransfer rate and show good electrocatalytic activity for theelectrooxidation of BPA. The sensor was characterized by variouselectrochemical methods such as cyclic voltammetry, ac impedancemethod, Difference pulse voltammetry, etc. Compared with bare GCE,the oxidation signal of BPA obtained by the modified electrodesigni?cantly increased; and this signal can be used to determine BPA.The experimental conditions were optimized and the electrochemicalparameters were calculated. Under optimum conditions, the responsecurrent of the modified electrode was proportional to BPAconcentration in the range from4.0×10-85.0×10-6M with a correlationcoef?cient of0.9944and detection limit of1.0×10-8M (S/N=3). Theproposed method was successfully applied to determine BPA.(3) A bisphenol A (BPA) biosensor was prepared by immobilizingtyrosinase and a nano-membrane combined with gold nanoparticlesand titanium dioxide nanoparticles (TiO2) on the surface of glassy carbon electrode (GCE). The sensor was characterized byelectrochemical method. The special structure of TiO2can effectivelyprevent the reunion of gold nanoparticles AuNPs and promote theelectronic transfer. Tyr keeps its biological activity in this composite film.Cyclic voltammetry showed that the cooperative effect of TiO2andAuNPs has not only improved the electronic transfer, but also elevatedthe electrochemical performance of the modified electrodes. In thecomposite film Tyr shows a good catalytic reduction properties to BPA.The experimental results showed that the current response of the sensorincreased linearly with the concentration of BPA from2×10-7to2.8×10-6mol L-1 with a relative coefficient of0.9967(n=14). The detection limit is5×10-5mol/L,=0.48mmol L-1.
Keywords/Search Tags:Nano Au-Ni materials, Bisphenol A, tyrosinase, Titaniumdioxide TiO2, Enzyme biosensor
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