Electrochemical Sensor for Electrochemically Inactive β-d(+)-Glucose Using α-Cyclodextrin Template Molecules

Abstract

We report an electrochemical sensor for an electrochemically inactive organic compound using a self-assembled monolayer (SAM) formed on the gold surface from a solution of thiolated alpha-cyclodextrin (alpha-CD). The SAM makes up an array of ultramicroelectrodes, which capture electroactive molecules such as those of ferrocene. When this SAM-modified electrode is exposed to a solution containing an electrochemically inactive compound, e.g., glucose, the captured ferrocene molecules are replaced by the electroinactive molecules via an equilibrium established between the two compounds, lowering the current for ferrocene oxidation. The decrease in current is directly proportional to the amount of glucose added and the glucose can be analyzed up to approximately 0.80 mM, which is approximately 1/10 of a typical physiological concentration in blood serum. Formation constants of the surface-bound alpha-CD molecules with ferrocene and glucose are also reported.

Emprego de monocamadas auto-organizadas no desenvolvimento de sensores eletroquímicos

“…Monocamadas auto-organizadas de α e β-ciclodextrinas modificadas com tióis e sulfetos têm sido preparadas para a detecção seletiva de compostos orgânicos [83][84][85][86][87] . Park e colaboradores 88 obtiveram monocamadas de β-ciclodextrinas sobre eletrodos de ouro e estudaram a inclusão de moléculas eletroativas com diferentes dimensões, tais como 2-metil-1,4-naftoquinona, p-benzoquinona e antraquinona.…”

Multiple DNA Binding Modes of a Metallointercalator Revealed by DNA Film Voltammetry

“…Using a density of 1.3 g/cm 3 for avidin, 19 the thickness of the protein layer was estimated to be approximately 8 nm, which suggests submonolayer coverage after taking into account the surface roughness of piranha-treated gold. 20 After deposition of CT-DNA from a 200 µg/mL solution on avidin-coated surface, the QCM frequency shift was in the range of -44 to -49 Hz. It can be estimated using the Sauerbrey equation that 318 ng/cm 2 nucleic acid was immobilized on the avidin-coated gold electrode.…”

Recognition of Bile Acids at Cyclodextrin-Modified Gold Electrodes

“…For this purpose, we used LP-β-CD or LP-γ -CD as a membrane element and bile acids as guest species (Scheme 1). This is because LP-β-CD and LP-γ-CD have been known to form SAM [8][9][10][11] and because bile acids are known as excellent guests for CD derivatives. [16][17][18][19] First, we determined the binding constants (Ksoln) of γ-CD with bile acids in homogeneous aqueous solution, employing a spectral displacement method 20 using phenolphthalein (PP) as a dye species.…”

“…4 Thus, several researchers have already reported the formation of selfassembled membranes (SAM) of CDs. [4][5][6][7][8][9][10] The evaluations of the molecular recognition properties of the resulting CD SAMs have been achieved with electrochemical measurements, [5][6][7][8][9][10][11][12] scanning probe microscopy, 13 surface-enhanced Raman scattering, 14 and quartz crystal microbalance. 15 Regarding sensor applications, electrochemical responses of some marker compounds (electrochemically active species existing in a bulk solution phase) were often used as signal transduction agents because of the ease in quantitative analyses for observed electrochemical responses.…”

“…15 Regarding sensor applications, electrochemical responses of some marker compounds (electrochemically active species existing in a bulk solution phase) were often used as signal transduction agents because of the ease in quantitative analyses for observed electrochemical responses. For this purpose, ferrocene [6][7][8][9][10][11] and quinone 12,15 derivatives have been used for realizing favorable signal transduction in voltammetric responses for the molecular recognition at the CD SAMs.…”