The Preparation And Properties Of Ascorbic Acid Oxidase Biosensor Based On BDD

This article taking diamond films, biosensors, chemically modified electrode as thetheoretical basis，combined boron-doped diamond （BDD） film with ascorbic acidoxidase.Taking boron-doped diamond thin film electrode as the substrate, this article adoptedthe methods of covalent bonding, embedding, as well as electrochemical polymerization tomodify ascorbic acid oxidase onto the BDD electrode, and thus achieved the ascorbic acidoxidase biosensor electrode. Then three modified electrodes were used as the workingelectrodes to test the ascorbic acid. According to the comparative analysis on the testingresults of different modified electrodes on ascorbic acid, it shows that compared to the BDDelectrodes not modified, those modified ones have larger peak current and smaller spikepotential. This means that chemically modified BDD electrode is able to reduce the activeover potential in testing ascorbic acid, and could overcome the interference of electroactivesubstances. ascorbic acid oxidase.The covalent /bonding method could bond the ascorbic acid oxidase units onto thesurface of the BDD electrons, and the attachment is firm through this modification agent, theelectrode is washable and could be soaked, in addition that it has better conductivity,repeatability, and stability than the electrodes of both the electrochemical polymerization typeand the absorbing modification type. This electrode has the maximum testing degree as1×10_-10mol/L.The embedding method could drop or coat the modifying fluids containingchemical groups onto the surface of the electrons so as to produce the solute coatingcontaining enzymes. This method could render the solute coating easier to be produced andmore convenient to be used, but it could not ensure the chemical groups to be stably attachedto the electrode, therefore the solute coating is of poor stability and repeatability. Theembedded modified electrode has the maximum testing degree as 1×10_-10mol/L.During theoxidation and polymerization process of o-phenylenediamine in the electrochemicalpolymerization method, enzymes are embedded into the carrier materials, the solidifyingprocess is finished without second effort, and the amount of the embedded enzymes could becontrolled by regulating the amount of the electricity during the polymerization process,resulting in that the obtained enzyme layers have high active unit content, even concentration,and faster electrochemical response than the modifying electrodes in the types of covalentbonding and embedding. Polymeric electrode has better sensitivity than the covalentbonding type, embedded fast modified electrode with the maximum testing degree as1×10_-11mol/L.