title: Direct electrochemistry of uric acid at chemically assembled carboxylated single-walled carbon nanotubes netlike electrode.
abstract: Carboxylated single-walled carbon nanotubes (SWCNT) chemically assembled on gold substrate was employed as netlike electrode to investigate the charge-transfer process and electrode process kinetics using uric acid as an example. The electrochemical behavior of uric acid in carboxylated SWCNT system was investigated using cyclic voltammetry, chronoamperometry, and single potential time-based techniques. The properties of raw SWCNT electrode were also studied for comparison purpose. Uric acid has better electrochemical behavior whereas ascorbic acid has no effective reaction on the carboxylated SWCNT electrode. Cyclic voltammograms indicate that the assembled carboxylated SWCNT increases more active sites on electrode surface and slows down the electron transfer between the gold electrode and uric acid in solution. The charge-transfer coefficient (alpha) for uric acid and the rate constant (k) for the catalytic reaction were calculated as 0.52 and 0.43 s(-1), respectively. The diffusion coefficient of 0.5 mM uric acid was 7.5 x 10(-6) cm2 x s(-1). The results indicate that electrode process in the carboxylated SWCNT electrode system is governed by the surface adsorption-controlled electrochemical process.
authors.affiliation: Nano-Bio-Electronic Lab, Department of Electrical Engineering and Computer Science, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, South Korea. xingjiuhuang@hotmail.com
authors.forename: Xing-Jiu
authors.initials: XJ
authors.lastname: Huang
authors.forename: Hyung-Soon
authors.initials: HS
authors.lastname: Im
authors.forename: Oktay
authors.initials: O
authors.lastname: Yarimaga
authors.forename: Ju-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Do-Hoon
authors.initials: DH
authors.lastname: Lee
authors.forename: Hak-Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Yang-Kyu
authors.initials: YK
authors.lastname: Choi
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D014527:Uric Acid / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D014527:Uric Acid; D001205:Ascorbic Acid