Ubiquinone-10 in gold-immobilized lipid membrane structures acts as a sensor for acetylcholine and other tetraalkylammonium cations

Abstract

This is an accepted version of a paper published in Bioelectrochemistry. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the published paper: Mårtensson, C., Agmo Hernańdez, V. (2012 AbstractIt is reported that the reduction of ubiquinone incorporated into supported lipid bilayers and into immobilized liposome layers on gold electrodes is kinetically and thermodynamically enhanced by the presence of acetylcholine and tetrabutylammonium (TBA + ) in solution. The reduction peak and the mid-peak potentials of the redox reactions, determined by cyclic voltammetry, are displaced towards more positive potentials by approximately 500 and 250 mV, respectively, in the case of TBA + ; and by approximately 750 and 530 mV, respectively, in the case of acetylcholine. The intensity of the signal varies with the cation concentration, allowing for quantitative determinations in the millimolar range. It is proposed that the enhanced reduction of ubiquinone arises from the formation of tetraalkylammonium cationubiquinone radical anion ion-pairs. Electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) measurements confirmed that the potential shift and the intensity of the redox signal are coupled with the adsorption of the tetraalkylammonium cations on the lipid membrane. The Langmuir adsorption equilibrium constant (K) of TBA + on lipid membranes at physiological pH is determined. In supported lipid bilayers K = 440.7 ± 160 M -1 , while in an immobilized liposome layer K = 35.53 ± 3.53 M -1 . 1

Electrochemistry of LB films of mixed MGDG:UQ on ITO

“…These observations are also valid for ITO-MGDG:UQ 10:1 (not shown). Our results are in line with the observations of Märtensson and Agmo [39] for scan rates < 1 V·s -1 , Gordillo and Schiffrin [9] and Li et al [40] for monolayers containing UQ confined on the electrode surface. The voltammograms presented in Fig.…”

“…3-5, show a non-symmetrical shape, being the reduction peak sharper than the oxidation one. A similar situation was observed by Märtensson and Agmo [39] and Hong and Park [41] studying UQ and hydroquinone respectively and was also observed studying the electrochemical behaviour of the ITO-DPPC:UQ/electrolyte system [21,22]. The different shape of reduction and oxidation peaks can be explained by the different hydrophilic character of the redox couple UQ/UQH2.…”

Label-Free Characterization of Peptide–Lipid Interactions Using Immobilized Lipodisks

“…They are also of great interest as systems to study membrane-analyte interactions, including the study of peptide-and protein-membrane interactions 4,5 . Furthermore, they can be used as supports for biologically relevant molecules, including membrane-bound receptors 6 , in a biomimetic environment 7 or as supporting media for hydrophobic electroactive molecules [8][9][10][11][12][13][14] leading to the development of sensors. However, two major drawbacks can be readily identified in these systems.…”

Redox chemistry of coenzyme Q—a short overview of the voltammetric features

“…The sensor was constructed by using its gel form that was mixed with multi-walled carbon nanotubes/ionic liquid. In another work [29], the authors have used CoQ10 supported in lipid bilayers to construct a sensor for acetylcholine detection. The features of several other CoQ-based voltammetric sensors are reported elsewhere [30].…”