Electrochemically Constructed Biological Functional Film On Au Surface And It's Application In Electroanalysis

The immobility and qualitative expression of active biological species at electrode surface are important research area in biological electrochemistry.The molecular recognition system constructed on the base of the biological film possessing particular physical and chemical properties is considered as an effective research road.The traditional biological functional film usually is constructed by either self-assembling(SA) or polymerization method.The self-assembling mothd is offen mainly oprated at the condition of open circuit potential,which might lead to an uncontrolable surface.The physical polymerization usually preforms under an extramine physical condition,which can damage the activation of biological species. Electrochemical method is a simple,smoth and effective means to keep the activtion of biological species during the prepare procedure of the biological funtional film.How to develope valuable electorchemistry construction method for the biological funtional film is an research area needed to be deeply expolred in biological electrochemistry.In this thesis,the optimum procedure for preparing the biological funtional film at the surface of polycrystalline Au electrode was been expolred,systemly.The self-assebling monolayer film of mercapto boric acid ramification(MBAR) was devepled at the Au surface under the controlled-potential condition.3-Thiopheneboronic acid(3-THB) polymerzation was obtained by electrochemical oxidation.The new method of electrochemically induced free-radical polymerization(EIRP) was firstly investigated and the poly(Methacrylic acid) film was successfully constructed at the Au electrode surface.Firstly,the polycrystalline Au electrode surfaces prepared by different pretreatment procedures were investigated in sulfuric acid by cyclic voltammetry.The experiment results showed the clear surface for polymerization can be obtained by mechanical mechanical polishing and chemical oxidation prodedures,but the best active surface for modification could be obtained after mechanical polishing,chemical oxidation,electrochemical polaration and chemical reduction procedures.Secodly,the self-assembling monolyaer of MBARs prepared by the controlled-potential method was analyzed by the cyclic voltammetry in ferricyanide potassium solution.It was found that the optimum controlled-potential for self-assembling was within the range of 0.4～0.5 V.The controlled-potential method made the charactersof the self-assembled monolayer better than that without one.The monolayer of monosaccharides could recognize the enantiomeric tartaric acids since L-tartaric acid more easily reacted with the monolayer than D-tartaric acid in neutral and weak acid solution.On the other hand,the monolayer of monosaccharides also could be applied in the selective detection of dopamine(DA) after preconcentration.Moreover,the longer chain MBAR detection response was more sensitive than the short one's.The former's liner response range was within 10～300μmol/L and the detection limit was down to 1μmol/L,while the latter's were 30～100μmol/L and 9μmol/L.Thirdly,the poly(3-THB) film obtained by electrochemcial oxidation had many boric acid functional groups possessing negative charge in neutral solution condition,which could enhance the response of DA in the formation of rigonal and tetrahedral esters and electrostatic repulsion. Meanwhile,The poly(3-THB) film could selective detect DA in the presence of 1 mmol/L Vitamine C(AA),1 mmol/L Uric acid(UA) or 1～2 mmol/L Glucose(GO).A new electrochemical polymerization method was explored in the last charper of this thesis. Under the conditions of neutral pH adquene and room temperature,the electrochemical reduction of potassium persulfate would offer steady free-radical,which could induce the polymerzation of methacrylic acid at Au electrode.AFM and other experimental results identified that polymerization film was a three-dimensional porous stucture excellectly adhesing on Au surface. When the polymerzation solution contained glucose oxidase(GOD),the film could effectively immobilize glucose oxidase(GOD) with highly active.Corresponding GOD enmyzer electrode could quickly,sensitivity and stabilitly response forβ-D glucose in solution.Under the optimal conditions,the detection limit was down to 0.5μmol/LFinally,after constrated the three films above,the EIRP method should be the newest construction way under the conditions of neutral pH adquene and room temperature to keep the activation of biological speies.Meanwhile,lots of affects still needs to be made along this way.