Dopamine Oxidation at Per(6‐deoxy‐6‐thio)‐α‐Cyclodextrin Monolayer Modified Gold Electrodes

Abstract

The gold electrode is functionalized by sequential self-assembly of a monolayer of the title thiolated cyclodextrin with and without dopamine included in the cavities. The structure of a-cyclodextrin modified gold electrode is carefully characterized using STM and AFM. Surface complexation of dopamine is examined and its association constant is evaluated. Chemical reactions accompanying the electrode process of dopamine, which interfere in the electrochemical dopamine determination, are described and the conditions to avoid them are proposed. Dopamine incorporated in the a-cyclodextrin sites anchored to the electrode surface was found to provide electrochemical contact of the electrode with the solution-resident dopamine. Dopamine present in the a-cyclodextrin cavities has different properties compared to dopamine in the bulk buffer solution and can act as a mediator for the dopamine molecules diffusing to the electrode. This unique mediation effect leads to improvement of the sensitivity of dopamine determination using the a-cyclodextrin modified electrode and a procedure for the determination of dopamine in large excess of ascorbate is proposed.

A spectrophotometric and NMR study on the formation of an inclusion complex between dopamine and a sulfonated cyclodextrin host

“…This can be attributed to the redox reactions of the leucodopaminechrome/ dopaminochrome couple, Eq. (5), which is formed through the cyclization reaction of dopamine-quinone [30,31]. However, this reduction peak is absent in the presence of the sulfonated b-CD, which indicates that the cyclization reaction of the quinone, generated through the oxidation of DA, is inhibited when the DA is included in the cyclodextrin cavity.…”

The selective detection of dopamine at a polypyrrole film doped with sulfonated β-cyclodextrins

“…This reaction leads to the regeneration of dopamine making it available for further electrochemical oxidation, complicating the analysis [7,8].…”

Interference‐Free Electrochemical Detection of Nanomolar Dopamine Using Doped Polypyrrole and Silver Nanoparticles

“…pH was evaluated to be 49mV/pH unit, which was very close to the anticipated Nernstian value for a two-electron, two-proton process [40]. A linear regression analysis Epa =0.447-0.049 pH (correlation coefficient, R 2 = 0.987) showed that the uptake of electrons was accompanied by an equal number of protons.…”