An approach to develope a PolyAnilline electrode
as an application of Electrochemical properties of Enzyme
< keyword : Conducting Polymer, Cytochrome C, Electron Transportation efficiency, Redox current>
In order to perform high-efficiency electron transportation between enzyme and electrode, a polyanilline electrode was developed. Relation between the surface morphology of the electrode and electron transportation of Cytochrome C (enzyme) - polyanilline electrode was investigated. Surface morphology of polyanilline film, developed on ITO electrode by Electrochemical synthesis was observed by AFM and in order to measure the electron transportation efficiency between the film and enzyme Cytochrome C, Redox current of the enzyme on the film was measured. Surface morphology of the film and Redox current of Cytochrome C were found variable according to the type of acid used to produce film.Spherical spot (of diameter 50-100 micro) was observed on the film-surface while H2SO4 was used and in this case Redox phenomenon of Cytochrome C was not observed.On the film surface synthesised from HCl chain of spherical dot(of diameter 30-70 micro) was observed , Redox phenomenon of Cytochrome C was clearly observed as well.
1.Introduction
Inside a biological entity considerable number of enzymes perform electron transportation between some particular molecules e.g. Cytochrome C, an enzyme of Electron Transportation system receives electron from cytochrome Reductase and gives it to Cytochrome Oxidase inside Mytochondria. If the electron transportation between two enzymes are possible to perform between enzyme and electrode, the control of enzyme-enzyme electron transportation is considered to be possible by controlling the electrode voltage. But electron transportation between normal metal electrode and enzyme are not so satisfactory due to
1>the considerable distance between the active part of the enzyme and electrode ;
2>the change of enzyme while it comes to the contact of metal electrode .
Hence in order to perform the enzyme-electrode electron transportation , a suitable type of Interface between enzyme and electrode was proposed to be introduced e.g. Ferocene(Fe) as a mediator during the electron transportation of Glucose Oxidase(GOD).Conducting Polymer is also experimented considering it a Moeculer-wire.Conducting Polymer film ,synthesised on electrode have been tried to perform the electron transportation between enzyme and conducting polymer.In this experiment we focused on Polyanilline among a pretty variety of conducting polymers.It is known that Polyanilline shows different characteristics due to the incoming and outgoing of Proton Ions and the morphology of Polyanilline film takes different structure due to different synthesis condition.Such surface morphology is considered to reflect the Micro condition like Interaction between Moeculer chain.It is important to consider the micro structure of polymer that can perform the electron transportation to the active part of the enzyme acting as a wire.That is why this experiment aims at the developement of a Polyanilline electrode in order to make possible the high-efficiency electron transportation by investigating the relationship between surface morphology of Polyanilline film synthesised under different condition and Cytochrome C-Polyanilline electrode electron transportation.
2.Experimental
2.1)Preparation of Polyanilline film
ITO glass plate was used for anode and Platinum was for kathode.Anilline(0.25M) dilluted in H2SO4/HCl/HBF4(concentration for each acid was 0.5N,1N,5N)solution was the electrolyte and Polyanilline film was synthesised by Electrochemically.Synthesis voltage was measured by Cyclicvolatnometry Process and for H2SO4,HCl and HBF4 the magnitude was measured 1.1V,0.9V and 0.85V respectevely.The mesurement system of Cyclicvolatnometry Process is shown in Fig.1.

2.2)Observation of Film surface
Surface of the synthesised Polyanilline film was observed by a Scanning type probe Microscope(SPI3800,DFM mode)
2.3)Measurement of CV(Voltage-Current) characteristic of the film
CV characteristic of the synthesised film was measured in pH6 Buffer(0.2M NaH2PO4.H2O and Na2HPO4.2H2O)using the anilline electrode as Working electrode(W.E).
2.4)Dedope of the film and observartion of surface morphology
Polyanilline electrode and Platinum plate was put in pH6 Buffer(0.25M) and dedoped for 10 minutes by connecting the electrodes through a resistence of 760 ohm.After cleaning by distilled water and drying, surface morphology of the dedoped film was observed by the Scanning type probe Microscope.
2.5)C-V characteristic of dedoped film
C-V characteristic of dedoped film was measured in pH6 Buffer(0.25M) and aquatic solution Cytochrome C (2.5gm/ml Cyt C/pH6 Buffer) seperately.The result was compared afterwards.
(the rest will be added soon)
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