Electro-chemistry Performance Of Electrode Over-coated By Nano-composite With Immobilized Blue Multi-copper Oxidase

In recent years,blue multi-copper oxidase as bio-electrocatalyst has been widely used in the field of cathode preparation for enzymatic fuel cell and enzyme based electrochemical sensor.However some defects limit its further application in industrial production,such as complicated process of preparation,poor mechanical /thermal stability and inferior anti-interence.It is more important that efficient electron communication has barely been achieved between active sites within enzymes and conductive supports.In respect to all above issues,several compounds containing hydrophobic aromatic ring or aromatic heterocycle and chemical bonding groups?i.e.conductive polymer originating from polymerization of aromatic monomer,chitosan derivatives and aromatic compounds with dual coupling groups?have been proposed to prepare carrier to accommodate protein through combination with nano-material.Enzyme molecules have been arrayed on the interface of matrix in the way of site-directed orientation or random adsorption through chemical coupling,physical adsorption and electrostatic attraction or synergetic effect of all above interactions.In this paper,electrochemical and spectroscopic methods were used to study and evaluate the direct electrochemistry between enzyme immobilized on the surface of nano-composite and conductive substrate,performance in catalysis to certain substrate for enzyme based electrodes and the influence of interaction between enzyme and carrier on the catalysis.On the basis of this,sensing function to specific substrate for these electrodes has been estimated further.1 The complex composed of functionalized nano gold particles and chitosan derivatives was proposed to act as the carrier to incorporate enzyme molecules.Synergistic effect mentioned previously would not only immobilize enzyme molecules firmly within the matrix in the way of oriented arrangement but also promoted the direct electron transfer between enzyme and basal electrode.Sensing function to catechol for this nano-complex based electrode with integrated enzyme molecules has been tested further.This novel electro-chemical catechol sensor based on nano-complex with Laccase exhibited such advantages as: high sensitivity,specifc response to aimed substrate and low detection limit.Moreover its sensing performace in monitoring substrate would not be interfered with oxygen molecules in co-existence.2 Polyaniline-cobalt oxalate?CoC₂O₄?nanocomposites as enzyme support was proposed to prepare blue multi-copper oxidase based biocathode.Direct electrochemistry and catalytic function on oxygen reduction for this Laccase based electrode were probed systematically.Experimental results indicated that direct electron transfer occurred between enzyme active site T2 and conductive matrix in the absence of any external mediator.But the catalytic reaction is controlled by the decomposing process of intermediate resulting from chemically attached oxygen molecules into water molecules.3 Laccase based electrode was prepared through dipping nano-composite with coupled enzyme onto the surface of electrode followed drying in air,which adopted carboxymethyl chitosan chemically coupled magnetic ferric trioxide magnetic nanoparticles as the enzyme carrier.Efficient charge shuttle and catalytic effect on oxygen reduction reaction for this kind of Laccase based electrode were investigated in this dissertation.Experimental results revealed valid electron transfer between basal conductive support and entrapped protein molecules and effective catalysis on reduction of substrate for this magnetic nano-particle with Laccase where enzyme molecules were distributed randomly on the interface of support in the help of chemical coupling,can be achieved only if the external electron relay was introduced into the system.Catalytic cycle in oxygen reduction reaction induced by Laccase was resrained by the step of electron mediator diffusion.