%0 Journal Article %T Sensitive Electrochemical Detection of Glucose at Glucose Oxidase-Cobalt Phthalocyanine-Modified Boron-Doped Diamond Electrode %A Takeshi Kondo %A Masaru Horitani %A Makoto Yuasa %J International Journal of Electrochemistry %D 2012 %I Hindawi Publishing Corporation %R 10.1155/2012/943957 %X Electrochemical detection of glucose was achieved at a glucose oxidase (GOx)-cobalt phthalocyanine (CoPc)-modified boron-doped diamond (BDD) electrode without any additional electron mediator in the electrolyte solution. The surface of the hydrogen-terminated BDD thin film prepared by microwave plasma-assisted CVD was modified with 4-vinylpyridine (4VP) via photochemical modification. The 4VP-BDD was then immersed in a CoPc solution to obtain CoPc-BDD. A poly(p-phenylenediamine) (PPD) thin film containing GOx was coated on the CoPc-BDD electrode surface via electropolymerization. At the GOx/PPD-CoPc-BDD electrode, anodic current for glucose oxidation was observed with a sigmoidal voltammetric curve, indicating successful electron mediation of H2O2 generated as the result of glucose oxidation at GOx. The signal-to-background ratio for voltammetric current of glucose detection was larger at the GOx/PPD-CoPc-BDD electrode than at the GOx/PPD-modified platinum electrode due to the smaller background current of the modified BDD electrode. 1. Introduction Highly boron-doped diamond (BDD) electrodes have been known to be a promising electrode material for sensitive electroanalysis based on the wide potential window and low background current as well as physical and chemical stability and biocompatibility [1]. Glucose is a compound, whose concentration is one of the most desired to be determined via electrochemical methods in relation to increasing demands for diabetes care [2]. In order to use BDD electrode for glucose detection, one should modify the surface with catalysts or enzymes due to the large overpotential for direct glucose oxidation at unmodified BDD electrodes. For glucose detection at BDD electrodes using electrocatalysts, Cu [3¨C5] and Ni [6¨C9] have been used for modification of the surfaces. Immobilization of particles or line patterns of these metals with micrometer or nanometer scale onto BDD surface enables sensitive glucose detection with low background current. On the other hand, BDD electrodes modified with glucose oxidase (GOx) [10¨C13] are advantageous because of their selectivity and sensitivity of the glucose molecule. In some cases, additional mediators, such as ferrocene carboxylic acid [11], were employed for glucose detection at GOx-modified BDD electrodes. Glucose detection without any additional reagents to samples is possible for simple analysis systems, and especially for monitoring concentration. Hydrogen peroxide is a product of glucose oxidation at GOx and thus can act as an electroactive mediator for electrochemical detection %U http://www.hindawi.com/journals/ijelc/2012/943957/