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Electrically controlled variation of receptor affinity

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ABSTRACT

A concept of virtual sensor array based on electrically controlled variation of affinity properties of the receptor layer is described. It was realized on the base of integrated electrochemical chemotransistor containing polyaniline as the receptor layer. Electrical control of the redox state of polyaniline was performed in five-electrode configuration containing four electrodes for conductivity measurements and one Ag/AgCl reference electrode. All the electrodes were integrated on the same glass chip. A room-temperature ionic liquid was used for the electrical connection between the reference electrode and chemosensitive material. Conductivity measurements demonstrated effective potential-controlled electrochemical conversions of the receptor material between different redox states. Binding of trimethylamine at three different potentials, corresponding to the different states of the receptor material, was studied. Concentration dependencies and binding kinetics were analyzed. The results demonstrated that the kinetic as well as the equilibrium binding properties of the receptor layer can be controlled by electrical potential, thus providing a possibility to form a virtual sensor array using only a single sensing element.

No MeSH data available.


Design and operation of the electrochemical chemotransistor. (a) The transistor is based on five-electrode configuration: four inner electrodes serve as working electrodes and are coated by polyaniline, and the outer strip forming a Ag/AgCl reference electrode is connected to the polyaniline coating by a thin layer of chloride-containing ionic liquid. (b) Electrical control of the conductance of polyaniline layer measured by four-point (circles) and two-point (squares) techniques. (c) Changes of the sensor signal (conductance measured by a four-point technique) due to subsequent injections of trimethylamine in the concentration of 1 – 0.81 ppm, 2 – 1.62 ppm, 3 – 3.26 ppm, 4 – 6.5 ppm, 5 – 13.0 ppm, and 6 – 26.0 ppm followed by an incubation in pure air
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Fig1: Design and operation of the electrochemical chemotransistor. (a) The transistor is based on five-electrode configuration: four inner electrodes serve as working electrodes and are coated by polyaniline, and the outer strip forming a Ag/AgCl reference electrode is connected to the polyaniline coating by a thin layer of chloride-containing ionic liquid. (b) Electrical control of the conductance of polyaniline layer measured by four-point (circles) and two-point (squares) techniques. (c) Changes of the sensor signal (conductance measured by a four-point technique) due to subsequent injections of trimethylamine in the concentration of 1 – 0.81 ppm, 2 – 1.62 ppm, 3 – 3.26 ppm, 4 – 6.5 ppm, 5 – 13.0 ppm, and 6 – 26.0 ppm followed by an incubation in pure air

Mentions: A functionality of the device as a transistor was studied by investigation of the influence of the potential difference between the reference electrode and low-potential outer measurement electrode (further referred as the gate potential) on the resistance of PANI layer. The results are presented in Fig. 1B. The obtained dependence corresponds to that reported in [6, 7] for electrochemical chemotransistors with aqueous gel electrolyte. The data demonstrate electrically controlled conversion of the polymer between three redox states. The first (reduced) state corresponds to the gate potential below −0.8 V. At the gate potential of −0.2 V, PANI is converted to another state. Further oxidation of PANI leads to its third oxidation state observed at the value of gate potential over +0.6 V. These states correspond probably to leucoemeraldine, emeraldine, and pernigraniline [8]. One can imagine that the three states of PANI have different affinity properties; therefore, these three potential values were used for electrochemical modification of sensor properties.Fig. 1


Electrically controlled variation of receptor affinity
Design and operation of the electrochemical chemotransistor. (a) The transistor is based on five-electrode configuration: four inner electrodes serve as working electrodes and are coated by polyaniline, and the outer strip forming a Ag/AgCl reference electrode is connected to the polyaniline coating by a thin layer of chloride-containing ionic liquid. (b) Electrical control of the conductance of polyaniline layer measured by four-point (circles) and two-point (squares) techniques. (c) Changes of the sensor signal (conductance measured by a four-point technique) due to subsequent injections of trimethylamine in the concentration of 1 – 0.81 ppm, 2 – 1.62 ppm, 3 – 3.26 ppm, 4 – 6.5 ppm, 5 – 13.0 ppm, and 6 – 26.0 ppm followed by an incubation in pure air
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5037141&req=5

Fig1: Design and operation of the electrochemical chemotransistor. (a) The transistor is based on five-electrode configuration: four inner electrodes serve as working electrodes and are coated by polyaniline, and the outer strip forming a Ag/AgCl reference electrode is connected to the polyaniline coating by a thin layer of chloride-containing ionic liquid. (b) Electrical control of the conductance of polyaniline layer measured by four-point (circles) and two-point (squares) techniques. (c) Changes of the sensor signal (conductance measured by a four-point technique) due to subsequent injections of trimethylamine in the concentration of 1 – 0.81 ppm, 2 – 1.62 ppm, 3 – 3.26 ppm, 4 – 6.5 ppm, 5 – 13.0 ppm, and 6 – 26.0 ppm followed by an incubation in pure air
Mentions: A functionality of the device as a transistor was studied by investigation of the influence of the potential difference between the reference electrode and low-potential outer measurement electrode (further referred as the gate potential) on the resistance of PANI layer. The results are presented in Fig. 1B. The obtained dependence corresponds to that reported in [6, 7] for electrochemical chemotransistors with aqueous gel electrolyte. The data demonstrate electrically controlled conversion of the polymer between three redox states. The first (reduced) state corresponds to the gate potential below −0.8 V. At the gate potential of −0.2 V, PANI is converted to another state. Further oxidation of PANI leads to its third oxidation state observed at the value of gate potential over +0.6 V. These states correspond probably to leucoemeraldine, emeraldine, and pernigraniline [8]. One can imagine that the three states of PANI have different affinity properties; therefore, these three potential values were used for electrochemical modification of sensor properties.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

A concept of virtual sensor array based on electrically controlled variation of affinity properties of the receptor layer is described. It was realized on the base of integrated electrochemical chemotransistor containing polyaniline as the receptor layer. Electrical control of the redox state of polyaniline was performed in five-electrode configuration containing four electrodes for conductivity measurements and one Ag/AgCl reference electrode. All the electrodes were integrated on the same glass chip. A room-temperature ionic liquid was used for the electrical connection between the reference electrode and chemosensitive material. Conductivity measurements demonstrated effective potential-controlled electrochemical conversions of the receptor material between different redox states. Binding of trimethylamine at three different potentials, corresponding to the different states of the receptor material, was studied. Concentration dependencies and binding kinetics were analyzed. The results demonstrated that the kinetic as well as the equilibrium binding properties of the receptor layer can be controlled by electrical potential, thus providing a possibility to form a virtual sensor array using only a single sensing element.

No MeSH data available.