Piezoelectric Electrochemistry Studies On Glucose Oxidase And Superoxide Dismutase Biosensors

Piezoelectric electrochemistry,which combines the techniques of electrochemistry with piezoelectric sensing,is capable of ultrasensitive mass measurements down to the nanogram level(generally equivalent to atomic and molecular monolayer or submonolayer modification)and the information on solution viscodensity and the elasticity of a foreign film,and has been presently one of the most effective tools for investigating the interface of liquid/solid.In the present thesis,we have carried out the following researches on the glucose oxidase(GOD)and super oxide dismutase(SOD)biosensors.The main contents are as follows:1.The development of enzyme biosensor,the basic concept of piezoelectric electrochemistry and its application in enzyme sensors.2.The electrochemical quartz crystal microbalance(EQCM)technique was employed to monitor in situ the adsorption of GOD onto Au electrodes, Au-electroplated electrodes and carbon nanotubes(CNTs)-modified Au electrodes.The enzymatic specific activities(ESA_i)for GOD adsorbed on various surfaces was evaluated by determining the amount of immobilized GOD and monitoring in situ the oxidative charge of enzyme-catalyzed product H₂O₂;the catalytic oxidation current produced by adsorptive GOD on seven different kinds of electrode surface was detected and SigmaPlot^? Scientific Graphing Software Version 2.0 software was utilized in conducting non-linear regression,consequently the Michaelis-Menten constants of enzyme catalyzed-reaction on each electrode was gained.3.A new promising biosensing platform based on entrapment GOD into the polymer developed during oxidation of noradrenalin(NA),with the modification of Prussian Blue(PB)and CNTs further improving the response performance,was developed.Thus,a novel glucose biosensor conducting detection at reductive potentials was fabricated.The electrochemical quartz crystal impedance analysis(EQCIA)method was used to monitor PB deposition,polymers from noradrenalin (PFNO)-synthesis and GOD-immobilization process;preparation conditions for the biosensor were optimized,the electrode performance was tested.This glucose biosensor possessed excellent performance.Particularly,the good anti-interferent ability at low applied potential is also expected to conquer the most troublesome problem about interferents going with nano-particles and it is reasonable to expect its extensive application in the preparation of nano-biosensors.4.A SOD biosensor was fabricated with cysteamine(Cy)as electron accelerator,and the direct electron transfer between the electrode and SOD was achieved.The electrochemical behavior of this sensor was thoroughly investigated and the reaction mechanism of SOD catalyzing the dismutation of O₂^- was explored;experimental conditions were all optimized;the electrode performance was tested;and the biosensor's responses towards O₂^-at oxidative and reductive potentials were all investigated.5 The electrochemical quartz crystal microbalance(EQCM)was used to track the adsorption process of SOD on the CNTs/Au electrode.The electrochemical behavior of SOD/CNT/Au electrode was investigated,the electroactivity of adsorbed SOD was quantitively estimated,and the storage stability of the SOD/CNTs/Au electrode and its current response towards O₂^-were also examined.