title: Enzyme biosensor based on plasma-polymerized film-covered carbon nanotube layer grown directly on a flat substrate.
abstract: We report a novel approach to fabrication of an amperometric biosensor with an enzyme, a plasma-polymerized film (PPF), and carbon nanotubes (CNTs). The CNTs were grown directly on an island-patterned Co/Ti/Cr layer on a glass substrate by microwave plasma enhanced chemical vapor deposition. The as-grown CNTs were subsequently treated by nitrogen plasma, which changed the surface from hydrophobic to hydrophilic in order to obtain an electrochemical contact between the CNTs and enzymes. A glucose oxidase (GOx) enzyme was then adsorbed onto the CNT surface and directly treated with acetonitrile plasma to overcoat the GOx layer with a PPF. This fabrication process provides a robust design of CNT-based enzyme biosensor, because of all processes are dry except the procedure for enzyme immobilization. The main novelty of the present methodology lies in the PPF and/or plasma processes. The optimized glucose biosensor revealed a high sensitivity of 38 μA mM(-1) cm(-2), a broad linear dynamic range of 0.25-19 mM (correlation coefficient of 0.994), selectivity toward an interferent (ascorbic acid), and a fast response time of 7 s. The background current was much smaller in magnitude than the current due to 10 mM glucose response. The low limit of detection was 34 μM (S/N = 3). All results strongly suggest that a plasma-polymerized process can provide a new platform for CNT-based biosensor design.
authors.affiliation: Department of Electronic Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan. muguruma@shibaura-it.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Muguruma
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hoshino
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Matsui
mesh_terms: D015374:Biosensing Techniques; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005949:Glucose Oxidase / Q000378:metabolism*; D037742:Nanotubes, Carbon; D013379:Substrate Specificity
chemical_list: D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D005949:Glucose Oxidase