Abstract In this work, a first demonstration of an hydrogel-gated organic field-effect transistor... more Abstract In this work, a first demonstration of an hydrogel-gated organic field-effect transistor (HGOFET) for the detection of water pollutants is described. Photosynthetic cyanobacteria were entrapped in a hydrogel grafted onto the platinum gate of the transistor. Photosynthesis was continuously monitored by electroreduction of the oxygen produced or consumed by the cyanobacteria on the gate electrode, under illumination or in the dark, respectively. The presence of herbicides such as diuron and glyphosate was found to strongly affect the cyanobacteria's photosynthetic activity, which was transduced into a significant drop of the device's gate current, strongly amplified onto the drain. This study demonstrates the suitability of HGOFETs for environmental monitoring.
Journal of Electroanalytical Chemistry, Feb 1, 2001
Dopamine uptake and release was investigated with a quinone-containing conducting film, poly(5-am... more Dopamine uptake and release was investigated with a quinone-containing conducting film, poly(5-amino-1,4-naphthoquinone) (PANQ), used for its intrinsic cation-exchange properties. The good electroactivity of this film in aqueous medium leads to interesting values of dopamine uptake, up to 100 nmol cm−2 in a 300 nm thick film. The uptake and release mechanisms indicate a water counterflow during the doping process and
Journal of Biomedical Materials Research, Sep 15, 1999
Oligonucleotides were incorporated into conducting films of poly(3, 4-ethylene dioxythiophene) by... more Oligonucleotides were incorporated into conducting films of poly(3, 4-ethylene dioxythiophene) by an electrochemical method that involves two steps. The electrode is first coated with the polymer film by electropolymerization followed by electrooxidation of the formed polymer in the presence of the oligonucleotide. Neutral water soluble polymers such as poly(vinylpyrrolidone) or poly(ethylene glycol) were added to the polymerizing medium resulting in higher incorporation yields of oligonucleotides. The results showed that a payload of about 1.5 nmol/cm2 can be achieved in an 8 micron thick film for an oligomer concentration of about 70 microM in the working solution. Various physical methods were used to analyze the surface of the polymer-coated electrodes. Results showed the presence of domains of varying sizes at the film surface, corresponding to the insertion of the hydrophilic polymer within the matrix of the conductive polymer. The release of entrapped oligonucleotides from the coated film exhibited a three-step profile: a "burst" period during the first 5 min followed by an intermediate and a very slow release period lasting several days. Such polymer films could be exploited as useful reservoirs of biologically active substances for in vivo delivery to targeted tissues. For example, coated stents that can release antiproliferative agents such as antisense oligonucleotides at the site of balloon dilatation may be of interest in the treatment of postangioplasty restenosis.
Versatile transduction scheme based on Electrolyte-Gated Organic Field-Effect Transistor used as ... more Versatile transduction scheme based on Electrolyte-Gated Organic Field-Effect Transistor used as Immunoassay readout system, Biosensors and Bioelectronic,
Organic Thin Film Transistors (OTFT), gated through an aqueous electrolyte, have extensively been... more Organic Thin Film Transistors (OTFT), gated through an aqueous electrolyte, have extensively been studied as sensors in various applications. These water-gated devices are known to work both as electrochemical (Organic ElectroChemical Transistor-OECT) and field-effect (Organic Field-Effect Transistor-OFET) devices. To properly model and predict the response of water-gated OTFT sensors it is important to distinguish between the mechanism, field-effect or electrochemical, by which the transistor is modulated and thus how the gate signal can be affected by the analyte. In this present study we explore three organic polymer semiconductors, poly-(3-hexyl-thiophene) (P3HT), poly-(3carboxy-pentyl-thiphene) (P3CPT) and a co-polymer P3HT-co-poly-(3-ethoxypentanoic acidthiophene) (monomer ratio 1:6, P3HT-COOH15) in water-gated OTFT structures. We report a set of transistor characteristics, including standard output parameters, impedance spectroscopy and current transients, to investigate the origin of the mode of operation in these water-gated OTFTs. Impedance characteristics, including both frequency and voltage dependence, were recorded for capacitor stacks corresponding to the gate/electrolyte/semiconductor/source structure. It is shown that P3HT as well as P3HT-COOH15 both can function as semiconductors in water gated OTFT devices operating in field-effect mode. P3CPT on the other hand shows typical signs of electrochemical mode Highlights When gated through an aq. media and depending on the concentration of carboxylic anchoring groups, the polythiophene material system can operate either in the pure fieldeffect or in the pure electrochemical mode of operation. In the polythiophene derivative with 15% of all the thiophene rings including COOHcontaining substituents (anchoring sites for receptors), the material can function as the transistor channel in a TFT operating in the field-effect mode of operation. However, with COOH-groups attached to every thiophene ring the semiconductor material operates in the pure electrochemical mode when included in a TFT structure. Our studies includes and presents a set of spectroscopic and current vs. voltage measurements which together provide a tool for scientists to judge upon the mode of operation, field-effect or electrochemical, in organic water-gated TFTs for sensor applications. The polythiophene material system, including 15% of anchoring sites, is thus an excellent candidate for potentiometric applications and in sensor applications in which the receptorto-transistor transduction rely on sensor signal transfer occurring at the electrolyte-water interface.
A reagentless lactate biosensor is described, based on an electropolymerized copolymer film poly(... more A reagentless lactate biosensor is described, based on an electropolymerized copolymer film poly(5-hydroxy-1,4-naphthoquinone-co-5hydroxy-3-acetic acid-1,4-naphthoquinone). The quinone group, as part of the polymer backbone, is electroactive and very stable in neutral aqueous medium. It can therefore act as an immobilized mediator for the enzyme recycling, at a working potential much lower than those commonly reported in the literature for other mediators. Experimental conditions for amperometric measurements (temperature, pH) are studied, especially the interference between quinone and molecular oxygen to investigate the enzyme/quinone recycling kinetic. Some well-known interferents are shown to have no measurable effect on the amperometric curves.
According to the World Health Organization, [1] approximately 1 in every 100 of the world's inhab... more According to the World Health Organization, [1] approximately 1 in every 100 of the world's inhabitants suffers from some form of neurological disorder such as epilepsy, Parkinson's disease, or Alzheimer's disease. These diseases arise from malfunctioning in the neurochemical signalling. Today's methods of treatment of those diseases focus primarily on pharmaceutical and electroceutical neuromodulation techniques to supress the effects of the disease or to restore healthy signalling. Both pharmaceutical (e.g., levodopa therapy) and electroceutical (e.g., deep brain stimulation [DBS]) therapies are associated with varying degrees of success. However, all therapies rely on the calibration of a delivery dose primarily dictated via external monitoring of the patient's symptoms and physiological state. A technology is lacking that enables the administration of chemical and electrical signals at high precision, in terms of spatiotemporal resolution, pharmaceutical specificity and dosage that takes the patient's specific physiological condition into an account. Signalling in the nervous system is based on gradients and transport of neurotransmitters (intercellular) and ions (intracellular). Abnormal neurotransmitter concentrations can reveal the state of a disease and can also be an early indicator of for instance a seizure. For example,
Stimuli-responsive hydrogels represent a class of materials capable of reversibly switching their... more Stimuli-responsive hydrogels represent a class of materials capable of reversibly switching their morphological and physicochemical characteristics. An ultrathin poly(acrylic acid) film (ca. 6 nm) grafted onto the gate of a p-type EGOFET is studied, and the correlation between the swelling state of the hydrogel and the transistor output characteristics is presented. The hydrogel-related swelling process occurring in basic medium causes an increase in threshold voltage due to the abrupt and intense increase of the negative charge density on the gate electrode. The variation of the drain current during the in situ modification of the pH electrolyte allows a quantitative analysis of the hydrogel switching kinetics. This work shows not only the relevance of EGOFET as an analytical tool in the broad sense, i.e., able to follow in real time phase transition processes of stimuliresponsive materials, but also the relevance of using a hydrogel for field-effectbased (bio)detection according to the ability of such material to overcome the well-known Debye length problematics.
Poly(5-amino-1,4-naphthoquinone), PANQ, ®lms are electroactive in both aqueous and organic soluti... more Poly(5-amino-1,4-naphthoquinone), PANQ, ®lms are electroactive in both aqueous and organic solutions. The redox process of both the ®lm and the quinone groups has been studied by MIRFTIRS and Probe Beam De¯ection. The quinone system is very stable in acetonitrile and in aqueous solutions up to pH 11. Therefore, its redox properties suggest potential applications in diverse areas.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The enzyme pyruvate oxidase (PyOD) covalently immobilized on an original conducting copolymer pol... more The enzyme pyruvate oxidase (PyOD) covalently immobilized on an original conducting copolymer poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic-1,4-naphthoquinone acid) can be recycled under anaerobic conditions, at +0.1V versus SCE. It is first demonstrated that the quinone group is an efficient co-substrate for PyOD in homogeneous conditions, then this efficiency is preserved when the quinone group is embedded in the polymer structure. The copolymer remains efficient
Organic electrochemical transistors (OECTs) are now well-known, robust and efficient as amplifica... more Organic electrochemical transistors (OECTs) are now well-known, robust and efficient as amplification devices for redox reactions, typically biologically ones. In contrast, electrolyte-gated organic field-effect transistors (EGOFETs) have never been described for that kind of application because field-effect transistors are known as capacitive coupled devices, i.e., driven by changes in capacitance at the electrolyte/gate or electrolyte/semiconductor interface. For such a kind of transistors, any current flowing at the gate electrode is seen as a drawback. However, we demonstrate in this paper that not only the gate potential can trigger the source-drain current of EGOFETs, which is the generally accepted mode of operation, but that the current flowing at the gate can also be used. Because EGOFETs can work directly in water, and as an example of application, we demonstrate the possibility to monitor microalgae photosynthesis through the direct measurement of photosynthetic O2 production within the transistor's electrolyte, thanks to its electroreduction on the EGOFET's gate. This paves the way for the use of EGOFETs for environmental monitoring.
A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center,... more A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases.
Featured Application: Animal testing will be soon replaced by better accepted and less expensive ... more Featured Application: Animal testing will be soon replaced by better accepted and less expensive in-vitro cell culture models, which explains the recent demand for real-time cell culture monitoring systems. They can bring high throughput screening and could be used not only for biomedical purposes (drug discovery, toxicology, protein expression, cancer diagnostic, etc.), but also for environmental ones (qualification of pollutants cocktails, for example). Beyond this, in-situ monitoring also participates in strengthening the fundamental knowledge about cells metabolism.
The electrooxidation of 2-methyl-5-amino-1,4-naphthoquinone (MANQ) on platinum or glassy carbon (... more The electrooxidation of 2-methyl-5-amino-1,4-naphthoquinone (MANQ) on platinum or glassy carbon (GC) electrodes in acetonitrile leads to poly(2-methyl-5-amino-1,4-naphthoquinone) (PMANQ) ®lms. Films were characterized by UV±VIS, X-ray photoelectron spectroscopy (XPS), ex situ FT-IR and in situ multiple internal re¯ection FT-IR spectroscopies (MIRFT-IRS). Results converge to a de®nition of the polymer structure, which is of the polyaniline type, bearing one methylquinone group per monomer unit. The electrochemical properties of PMANQ ®lm in organic and aqueous media were studied by MIRFT-IRS and in situ d.c. conductivity. The ®lm is conducting in negative as well as in positive potential range.
In this work, we developed graphene quantum dot-supported silver nanoparticles (AgNPs@GQDs) as Na... more In this work, we developed graphene quantum dot-supported silver nanoparticles (AgNPs@GQDs) as Nanozyme for efficient electrocatalytic reduction of H2O2. We applied this composite material in a glucose oxidase-based glucose sensor, by drop casting a mixture of AgNPs@GQDs and chitosan (CS) on glassy carbon electrodes (GCE). Various conditions such as thickness of the AgNPs@GQDs/CS film, pH and temperatures were optimized. The proposed sensor presented excellent selectivity and sensitivity, a linear dependence on glucose concentration in the range 0.1–10 mM and a limit of detection of ca. 0.01 mM.
Abstract We demonstrate that electrolyte-gated organic field-effect transistors (EGOFETs) can det... more Abstract We demonstrate that electrolyte-gated organic field-effect transistors (EGOFETs) can detect extremely minute modifications in the composition of the electrochemical double layers forming at the channel/electrolyte and gate/electrolyte interfaces, thus permitting real-time monitoring of alkylthiols self-assembling on a gold surface. We used this property to assay the enzymatic activity of acetylcholinesterase which, in the presence of its substrate (acetylthiocholine), produces thiocholine.
Abstract In this work, a first demonstration of an hydrogel-gated organic field-effect transistor... more Abstract In this work, a first demonstration of an hydrogel-gated organic field-effect transistor (HGOFET) for the detection of water pollutants is described. Photosynthetic cyanobacteria were entrapped in a hydrogel grafted onto the platinum gate of the transistor. Photosynthesis was continuously monitored by electroreduction of the oxygen produced or consumed by the cyanobacteria on the gate electrode, under illumination or in the dark, respectively. The presence of herbicides such as diuron and glyphosate was found to strongly affect the cyanobacteria's photosynthetic activity, which was transduced into a significant drop of the device's gate current, strongly amplified onto the drain. This study demonstrates the suitability of HGOFETs for environmental monitoring.
Journal of Electroanalytical Chemistry, Feb 1, 2001
Dopamine uptake and release was investigated with a quinone-containing conducting film, poly(5-am... more Dopamine uptake and release was investigated with a quinone-containing conducting film, poly(5-amino-1,4-naphthoquinone) (PANQ), used for its intrinsic cation-exchange properties. The good electroactivity of this film in aqueous medium leads to interesting values of dopamine uptake, up to 100 nmol cm−2 in a 300 nm thick film. The uptake and release mechanisms indicate a water counterflow during the doping process and
Journal of Biomedical Materials Research, Sep 15, 1999
Oligonucleotides were incorporated into conducting films of poly(3, 4-ethylene dioxythiophene) by... more Oligonucleotides were incorporated into conducting films of poly(3, 4-ethylene dioxythiophene) by an electrochemical method that involves two steps. The electrode is first coated with the polymer film by electropolymerization followed by electrooxidation of the formed polymer in the presence of the oligonucleotide. Neutral water soluble polymers such as poly(vinylpyrrolidone) or poly(ethylene glycol) were added to the polymerizing medium resulting in higher incorporation yields of oligonucleotides. The results showed that a payload of about 1.5 nmol/cm2 can be achieved in an 8 micron thick film for an oligomer concentration of about 70 microM in the working solution. Various physical methods were used to analyze the surface of the polymer-coated electrodes. Results showed the presence of domains of varying sizes at the film surface, corresponding to the insertion of the hydrophilic polymer within the matrix of the conductive polymer. The release of entrapped oligonucleotides from the coated film exhibited a three-step profile: a "burst" period during the first 5 min followed by an intermediate and a very slow release period lasting several days. Such polymer films could be exploited as useful reservoirs of biologically active substances for in vivo delivery to targeted tissues. For example, coated stents that can release antiproliferative agents such as antisense oligonucleotides at the site of balloon dilatation may be of interest in the treatment of postangioplasty restenosis.
Versatile transduction scheme based on Electrolyte-Gated Organic Field-Effect Transistor used as ... more Versatile transduction scheme based on Electrolyte-Gated Organic Field-Effect Transistor used as Immunoassay readout system, Biosensors and Bioelectronic,
Organic Thin Film Transistors (OTFT), gated through an aqueous electrolyte, have extensively been... more Organic Thin Film Transistors (OTFT), gated through an aqueous electrolyte, have extensively been studied as sensors in various applications. These water-gated devices are known to work both as electrochemical (Organic ElectroChemical Transistor-OECT) and field-effect (Organic Field-Effect Transistor-OFET) devices. To properly model and predict the response of water-gated OTFT sensors it is important to distinguish between the mechanism, field-effect or electrochemical, by which the transistor is modulated and thus how the gate signal can be affected by the analyte. In this present study we explore three organic polymer semiconductors, poly-(3-hexyl-thiophene) (P3HT), poly-(3carboxy-pentyl-thiphene) (P3CPT) and a co-polymer P3HT-co-poly-(3-ethoxypentanoic acidthiophene) (monomer ratio 1:6, P3HT-COOH15) in water-gated OTFT structures. We report a set of transistor characteristics, including standard output parameters, impedance spectroscopy and current transients, to investigate the origin of the mode of operation in these water-gated OTFTs. Impedance characteristics, including both frequency and voltage dependence, were recorded for capacitor stacks corresponding to the gate/electrolyte/semiconductor/source structure. It is shown that P3HT as well as P3HT-COOH15 both can function as semiconductors in water gated OTFT devices operating in field-effect mode. P3CPT on the other hand shows typical signs of electrochemical mode Highlights When gated through an aq. media and depending on the concentration of carboxylic anchoring groups, the polythiophene material system can operate either in the pure fieldeffect or in the pure electrochemical mode of operation. In the polythiophene derivative with 15% of all the thiophene rings including COOHcontaining substituents (anchoring sites for receptors), the material can function as the transistor channel in a TFT operating in the field-effect mode of operation. However, with COOH-groups attached to every thiophene ring the semiconductor material operates in the pure electrochemical mode when included in a TFT structure. Our studies includes and presents a set of spectroscopic and current vs. voltage measurements which together provide a tool for scientists to judge upon the mode of operation, field-effect or electrochemical, in organic water-gated TFTs for sensor applications. The polythiophene material system, including 15% of anchoring sites, is thus an excellent candidate for potentiometric applications and in sensor applications in which the receptorto-transistor transduction rely on sensor signal transfer occurring at the electrolyte-water interface.
A reagentless lactate biosensor is described, based on an electropolymerized copolymer film poly(... more A reagentless lactate biosensor is described, based on an electropolymerized copolymer film poly(5-hydroxy-1,4-naphthoquinone-co-5hydroxy-3-acetic acid-1,4-naphthoquinone). The quinone group, as part of the polymer backbone, is electroactive and very stable in neutral aqueous medium. It can therefore act as an immobilized mediator for the enzyme recycling, at a working potential much lower than those commonly reported in the literature for other mediators. Experimental conditions for amperometric measurements (temperature, pH) are studied, especially the interference between quinone and molecular oxygen to investigate the enzyme/quinone recycling kinetic. Some well-known interferents are shown to have no measurable effect on the amperometric curves.
According to the World Health Organization, [1] approximately 1 in every 100 of the world's inhab... more According to the World Health Organization, [1] approximately 1 in every 100 of the world's inhabitants suffers from some form of neurological disorder such as epilepsy, Parkinson's disease, or Alzheimer's disease. These diseases arise from malfunctioning in the neurochemical signalling. Today's methods of treatment of those diseases focus primarily on pharmaceutical and electroceutical neuromodulation techniques to supress the effects of the disease or to restore healthy signalling. Both pharmaceutical (e.g., levodopa therapy) and electroceutical (e.g., deep brain stimulation [DBS]) therapies are associated with varying degrees of success. However, all therapies rely on the calibration of a delivery dose primarily dictated via external monitoring of the patient's symptoms and physiological state. A technology is lacking that enables the administration of chemical and electrical signals at high precision, in terms of spatiotemporal resolution, pharmaceutical specificity and dosage that takes the patient's specific physiological condition into an account. Signalling in the nervous system is based on gradients and transport of neurotransmitters (intercellular) and ions (intracellular). Abnormal neurotransmitter concentrations can reveal the state of a disease and can also be an early indicator of for instance a seizure. For example,
Stimuli-responsive hydrogels represent a class of materials capable of reversibly switching their... more Stimuli-responsive hydrogels represent a class of materials capable of reversibly switching their morphological and physicochemical characteristics. An ultrathin poly(acrylic acid) film (ca. 6 nm) grafted onto the gate of a p-type EGOFET is studied, and the correlation between the swelling state of the hydrogel and the transistor output characteristics is presented. The hydrogel-related swelling process occurring in basic medium causes an increase in threshold voltage due to the abrupt and intense increase of the negative charge density on the gate electrode. The variation of the drain current during the in situ modification of the pH electrolyte allows a quantitative analysis of the hydrogel switching kinetics. This work shows not only the relevance of EGOFET as an analytical tool in the broad sense, i.e., able to follow in real time phase transition processes of stimuliresponsive materials, but also the relevance of using a hydrogel for field-effectbased (bio)detection according to the ability of such material to overcome the well-known Debye length problematics.
Poly(5-amino-1,4-naphthoquinone), PANQ, ®lms are electroactive in both aqueous and organic soluti... more Poly(5-amino-1,4-naphthoquinone), PANQ, ®lms are electroactive in both aqueous and organic solutions. The redox process of both the ®lm and the quinone groups has been studied by MIRFTIRS and Probe Beam De¯ection. The quinone system is very stable in acetonitrile and in aqueous solutions up to pH 11. Therefore, its redox properties suggest potential applications in diverse areas.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The enzyme pyruvate oxidase (PyOD) covalently immobilized on an original conducting copolymer pol... more The enzyme pyruvate oxidase (PyOD) covalently immobilized on an original conducting copolymer poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-thioacetic-1,4-naphthoquinone acid) can be recycled under anaerobic conditions, at +0.1V versus SCE. It is first demonstrated that the quinone group is an efficient co-substrate for PyOD in homogeneous conditions, then this efficiency is preserved when the quinone group is embedded in the polymer structure. The copolymer remains efficient
Organic electrochemical transistors (OECTs) are now well-known, robust and efficient as amplifica... more Organic electrochemical transistors (OECTs) are now well-known, robust and efficient as amplification devices for redox reactions, typically biologically ones. In contrast, electrolyte-gated organic field-effect transistors (EGOFETs) have never been described for that kind of application because field-effect transistors are known as capacitive coupled devices, i.e., driven by changes in capacitance at the electrolyte/gate or electrolyte/semiconductor interface. For such a kind of transistors, any current flowing at the gate electrode is seen as a drawback. However, we demonstrate in this paper that not only the gate potential can trigger the source-drain current of EGOFETs, which is the generally accepted mode of operation, but that the current flowing at the gate can also be used. Because EGOFETs can work directly in water, and as an example of application, we demonstrate the possibility to monitor microalgae photosynthesis through the direct measurement of photosynthetic O2 production within the transistor's electrolyte, thanks to its electroreduction on the EGOFET's gate. This paves the way for the use of EGOFETs for environmental monitoring.
A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center,... more A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases.
Featured Application: Animal testing will be soon replaced by better accepted and less expensive ... more Featured Application: Animal testing will be soon replaced by better accepted and less expensive in-vitro cell culture models, which explains the recent demand for real-time cell culture monitoring systems. They can bring high throughput screening and could be used not only for biomedical purposes (drug discovery, toxicology, protein expression, cancer diagnostic, etc.), but also for environmental ones (qualification of pollutants cocktails, for example). Beyond this, in-situ monitoring also participates in strengthening the fundamental knowledge about cells metabolism.
The electrooxidation of 2-methyl-5-amino-1,4-naphthoquinone (MANQ) on platinum or glassy carbon (... more The electrooxidation of 2-methyl-5-amino-1,4-naphthoquinone (MANQ) on platinum or glassy carbon (GC) electrodes in acetonitrile leads to poly(2-methyl-5-amino-1,4-naphthoquinone) (PMANQ) ®lms. Films were characterized by UV±VIS, X-ray photoelectron spectroscopy (XPS), ex situ FT-IR and in situ multiple internal re¯ection FT-IR spectroscopies (MIRFT-IRS). Results converge to a de®nition of the polymer structure, which is of the polyaniline type, bearing one methylquinone group per monomer unit. The electrochemical properties of PMANQ ®lm in organic and aqueous media were studied by MIRFT-IRS and in situ d.c. conductivity. The ®lm is conducting in negative as well as in positive potential range.
In this work, we developed graphene quantum dot-supported silver nanoparticles (AgNPs@GQDs) as Na... more In this work, we developed graphene quantum dot-supported silver nanoparticles (AgNPs@GQDs) as Nanozyme for efficient electrocatalytic reduction of H2O2. We applied this composite material in a glucose oxidase-based glucose sensor, by drop casting a mixture of AgNPs@GQDs and chitosan (CS) on glassy carbon electrodes (GCE). Various conditions such as thickness of the AgNPs@GQDs/CS film, pH and temperatures were optimized. The proposed sensor presented excellent selectivity and sensitivity, a linear dependence on glucose concentration in the range 0.1–10 mM and a limit of detection of ca. 0.01 mM.
Abstract We demonstrate that electrolyte-gated organic field-effect transistors (EGOFETs) can det... more Abstract We demonstrate that electrolyte-gated organic field-effect transistors (EGOFETs) can detect extremely minute modifications in the composition of the electrochemical double layers forming at the channel/electrolyte and gate/electrolyte interfaces, thus permitting real-time monitoring of alkylthiols self-assembling on a gold surface. We used this property to assay the enzymatic activity of acetylcholinesterase which, in the presence of its substrate (acetylthiocholine), produces thiocholine.
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