Electrochemical Functionalization of a Gold Electrode with Redox-Active Self-Assembled Monolayer for Electroanalytical Application

Behera, Susmita and Sampath, S and Raj, C Retna (2008) Electrochemical Functionalization of a Gold Electrode with Redox-Active Self-Assembled Monolayer for Electroanalytical Application. In: Journal of Physical Chemistry C, 112 (10). pp. 3734-3740.

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Abstract

The electrochemical functionalization of a Au electrode with a redox-active monolayer and the electroanalytical applications of the functionalized electrode are described. Reaction of the electrochemically derived o-quinone on the self-assembled monolayer (SAM) of 6-mercaptopurine (MPU) on a Au electrode gives a redox-active 4-(6-mercapto-purin-9-yl)benzene-1,2-diol (MPBD) self-assembly under optimized conditions. Electrochemical quartz crystal microbalance technique has been employed to follow the functionalization of the electrode in real time. Electrochemically derived o-quinone reacts at the N(9) position of the self-assembled MPU in neutral pH. Raman spectral measurement confirms the reaction of o-quinone on MPU self-assembly. MPBD shows a well-defined reversible redox response, characteristic of a surface-confined redox mediator at 0.21 V in neutral pH. The anodic peak potential (Epa) of MPBD shifts by −60 mV while changing the solution pH by 1 unit, indicating that the redox reaction involves two electrons and two protons. The surface coverage (Γ) of MPBD was 7.2 ± 0.3 × 10-12 mol/cm2. The apparent heterogeneous rate constant (ksapp) for MPBD was 268 ± 6 s-1. MPBD efficiently mediates the oxidation of nicotinamide adenine dinucleotide (NADH) and ascorbate (AA). A large decrease in the overpotential and significant increase in the peak current with respect to the unmodified electrode has been observed. Surface-confined MPBD has been successfully used for the amperometric sensing of NADH and AA in neutral pH at the nanomolar level.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry C
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	30 Mar 2010 12:30
Last Modified:	19 Sep 2010 05:57
URI:	http://eprints.iisc.ac.in/id/eprint/26263

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