Kinetic and Adsorption Studies of Biogenic Amine Neurotransmitters at Polycrystalline Diamond Microelectrodes
High sensitivity, 1-10 nM detection, of biogenic amine neurotransmitters was achieved using fast-scan cyclic voltammetry at hydrogen-terminated diamond microelectrodes. This reduced to 1-10 μM after 5-10 runs. To attempt to understand the sensitivity decrease, electron transfer kinetics, baseline current, and rate-limiting step for high (μM) and low (nM) concentrations were compared. Dopamine oxidation kinetics slowed after repeated scans, ΔEp increased from 0.142 to 0.805 V. Baseline current decreased by 50%. The rate-limiting step, measured only at the conditioned surface, was diffusion limiting. The high quality of our electrodes was verified by the voltage window in 0.5 M H2SO4 and by Raman spectroscopy. Dopamine and serotonin oxidation kinetics were characterized at more sensitive, sulfophenyl-terminated diamond microelectrodes; the responses were diffusion limited. These data were qualitatively consistent with surface chemistry changes after scanning, but do not adequately explain the sensitivity decrease. Additional testing of hydrogen- terminated surfaces is needed to provide insight.
The Electrochemical Society
Digital Object Identifier (DOI)
J. M. Halpern, S. Xie, J. L. Schreiber, and H. B. Martin, ‘Kinetic and Adsorption Studies of Biogenic Amine Neurotransmitters at Polycrystalline Diamond Microelectrodes’, ECS Transactions, vol. 3, no. 28, pp. pp. 47–57, 2007.
© 2007 ECS - The Electrochemical Society