[13p-PB5-1~9] 12.7 Biomedical Engineering and Biochips

[13p-PB5-7] Mechanism of Amperometric Biosensor with Electronically Type-Controlled Carbon Nanotube

〇hiroki hidaka¹ (1.SIT)

Keywords:Carbon nanotubes,Biosensor

An amperometric enzyme biosensor with electronically type-controlled (metallic and semiconducting) single-walled carbon nanotubes (CNTs) for use in aqueous media is presented. This research investigates how the electronic types of CNTs influence the amperometric response of enzyme biosensors. To conduct a clear evaluation, a simple layer-by-layer process based on a plasma-polymerized nano thin film (PPF) was adopted because a PPF is an inactive matrix that can form a well-defined nanostructure composed of CNTs and enzyme. In the presence of oxygen, the response of a metallic CNT-enzyme (glucose oxidase; GOD) electrode was 2 times larger than that of a semiconducting CNT-GOD electrode. In contrast, in the absence of oxygen, the response of the semiconducting CNT-GOD electrode was retained, whereas that of the metallic SWNT-GOD electrode was significantly reduced. This indicates that direct electron transfer occurred with the semiconducting CNT-GOD electrode, whereas the metallic CNT-GOD electrode was dominated by a hydrogen peroxide pathway caused by an enzymatic reaction. Electrochemical impedance spectroscopy was used to show that the semiconducting SWNT network has less resistance for electron transfer than the metallic CNT network. Therefore, it was concluded that semiconducting CNTs are more suitable than metallic CNTs for amperometric enzyme biosensors in terms of direct electron transfer as a detection mechanism. This study makes a valuable contribution toward the development of amperometric biosensors that employ controlled CNTs and various enzymes.