title: A fully microfabricated carbon nanotube three-electrode system on glass substrate for miniaturized electrochemical biosensors.
abstract: We present an integration process to fabricate single-walled carbon nanotube (SWCNT) three-electrode systems on glass substrate for electrochemical biosensors. Key issues involve optimization of the SWCNT working electrode to achieve high sensitivity, developing an optimal Ag/AgCl reference electrode with good stability, and process development to integrate these electrodes. Multiple spray coatings of the SWCNT film on glass substrate enabled easier integration of the SWCNT film into an electrochemical three-electrode system. O₂ plasma etching and subsequent activation of spray-coated SWCNT films were needed to pattern and functionalize the SWCNT working electrode films without serious damage to the SWCNTs, and to remove organic residues. The microfabricated three-electrode systems were characterized by microscopic and spectroscopic techniques, and the electrochemical properties were investigated using cyclic voltammetry and chrono-amperometry. The fully-integrated CNT three-electrode system showed an effective working electrode area about three times larger than its geometric surface area and an improved electrochemical activity for hydrogen peroxide decomposition. Finally, the effectiveness of miniaturized pf-SWCNT electrodes as biointerfaces was examined by applying them to immunosensors to detect Legionella(L) pneumophila, based on a direct sandwich enzyme-linked immunosorbent assay (ELISA) format with 3,3',5,5'-tetramethylbenzidine dihydrochloride/hydrogen peroxide(TMB/H₂O₂) as the substrate/mediator system. The lower detection limit of the pf-SWCNT-based immunosensors to L. pneumophila is about 1500 times lower than that of the standard ELISA assay.
authors.affiliation: Department of Biomicrosystem Technology, Korea University, Seoul, Seongbuk-gu 136-713, Republic of Korea.
authors.forename: Joon Hyub
authors.initials: JH
authors.lastname: Kim
authors.forename: Jun-Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Joon-Hyung
authors.initials: JH
authors.lastname: Jin
authors.forename: Chan Won
authors.initials: CW
authors.lastname: Park
authors.forename: Cheol Jin
authors.initials: CJ
authors.lastname: Lee
authors.forename: Nam Ki
authors.initials: NK
authors.lastname: Min
mesh_terms: D001560:Benzidines / Q000378:metabolism; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D004867:Equipment Design / Q000295:instrumentation*; D005898:Glass / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000378:metabolism; D016952:Legionella pneumophila / Q000302:isolation & purification; D057230:Limit of Detection; D008839:Microelectrodes; D018625:Microscopy, Atomic Force; D055616:Microtechnology / Q000295:instrumentation* / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D013059:Spectrum Analysis, Raman
chemical_list: D001560:Benzidines; D037742:Nanotubes, Carbon; C021758:3,3',5,5'-tetramethylbenzidine; D006861:Hydrogen Peroxide