Thierry Noguer - Academia.edu (original) (raw)

Papers by Thierry Noguer

Talanta, 2003

Three strategies have been compared to produce screen-printed amperometric detectors for NADH: mi... more Three strategies have been compared to produce screen-printed amperometric detectors for NADH: mixing Meldola Blue (MB) in the screen-printing ink, incorporation of MB Á/Reinecke salt (MBRS) in the graphite ink and electrodeposition of films of MB-derived polymer (poly (MB)) on electrode surface. Following modification of graphite electrodes the mediators displayed values of the formal potential E 8? from (/0.129 to (/0.160 V vs. Ag/AgCl and pK a s of 5.09 Á/6.02. A second redox couple with E 8?0/(/0.450 V vs. Ag/AgCl was observed in cyclic voltammetry experiments with poly (MB) sensors or with old electrodes obtained according to the other two strategies. Electropolymerisation of MB allowed to achieve the best operational stability and best detection limit, 2 )/10 (6 M, for amperometric detection of NADH, while the most extended linear range, 1 )/10 (5 Á/7.5)/10 (4 M, corresponds to sensors with MBRS. MB and MBRS electrodes were compared with a similar NADH detector produced by Gwent Electronic Materials, England. Several characteristics of the modified-electrodes induced by the fabrication by screenprinting were also highlighted. #

Biosensors and Bioelectronics, 2003

Electropolymerization of Meldola Blue was carried out by cyclic voltammetry in the range from (/0... more Electropolymerization of Meldola Blue was carried out by cyclic voltammetry in the range from (/0.6 to '/1.4 V vs. Ag/AgCl, thus defining a new immobilization procedure of the phenoxazine mediator on screen-printed graphite electrodes. Evidence of polymer formation was provided by electrochemical and Fourier transform infrared spectroscopy (FTIR) data. Following polymerization, Meldola Blue preserved the ability to catalyze NADH oxidation allowing to achieve a detection limit of 2.5 )/10 (6 mol l (1 and a sensitivity of 3713 mA l mol (1 in amperometric determinations at 0 V vs. Ag/AgCl. In addition, the polymeric mediator was found to facilitate the reduction of hydrogen peroxide in the absence of peroxidase. Typical calibration at (/0.1 V vs. Ag/AgCl shows a detection limit of 8.5 )/10 (5 mol l (1 , a sensitivity of 494 mA l mol (1 and a linear range from 2.5 )/10 (4 to 5 )/ 10 (3 mol l (1 hydrogen peroxide. #

Analytica Chimica Acta, 2002

Biosensors for d-lactate and acetaldehyde were developed, based on screen-printed electrodes and ... more Biosensors for d-lactate and acetaldehyde were developed, based on screen-printed electrodes and NAD + -dependent dehydrogenases. Modification of screen-printed electrodes with the mediator Meldola Blue or with Meldola Blue-Reinecke salt resulted in sensitive, low cost and reliable NADH detectors. The biosensors were realised in two configurations, as disposable and reusable devices. Single-use sensors were obtained by simple deposition of enzyme and cofactor on the surface of mediator-modified electrodes. Chronoamperometry was used for the detection of substrates in small volumes of samples (25 l). Immobilisation of dehydrogenases by entrapment in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) allowed sensors to be obtained with sufficient operational stability. Amperometry in stirred solutions was the detection technique with biosensors for multiple use. The 3σ detection limits for acetaldehyde were 1 M by amperometry and 6 M by chronoamperometry and for d-lactate-0.03 M and 0.05 M for reusable and disposable biosensors respectively.

Journal of AOAC International

A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The senso... more A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The sensor is based on the association of screen-printed carbon electrodes and aldehyde dehydrogenase immobilized by a sol-gel entrapment method. Modification of screen-printed carbon electrodes with Reinecke salt of Meldola's Blue (MBRS) resulted in highly sensitive and interference-free nicotinamide-adenine dinucleotide (NADH) detectors. Based on MBRS-mediated oxidation of NADH at -150 mV versus pseudo Ag/AgCl, acetaldehyde was determined in the range 10-260 microM, compatible with wine quality monitoring. The method of immobilization based on sol-gel entrapment was optimized to obtain the best compromise between sensitivity and operational stability. The sensor response was stable for 40 consecutive assays with methyltrimethoxysilane used as alkoxide precursor, thus allowing a possible calibration of the sensor before each measurement. The biosensors were used to analyze French wines. The method was validated with a commercially available enzymatic kit based on a standard spectrophotometric method.

Analytical and Bioanalytical Chemistry, 2002

Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in bio... more Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in biosensors based on NAD + -dependent dehydrogenases, tyrosinase, or genetically modified acetylcholinesterases. The mono-enzyme sensors have been optimized as disposable or reusable devices for detection of a variety of substrates important in the food industry (D-lactic acid, L-lactic acid, acetaldehyde) or in environmental pollution control (phenols and dithiocarbamate, carbamate and organophosphorus pesticides). The sensors were prepared in four configurations differing in enzyme confinement, enzyme immobilization and location of the immobilization agent in the biosensor assembly. Tests on real samples have been performed with the biosensors; D-lactic acid and acetaldehyde have been detected in wine and phenols in air.

Analytica Chimica Acta, 2001

A reagentless biosensor for d-lactate was developed using the screen-printing technology. In a si... more A reagentless biosensor for d-lactate was developed using the screen-printing technology. In a simple design, d-lactate dehydrogenase and NAD + were deposited onto the surface of a carbon electrode, modified with an insoluble salt of Meldola's Blue. The detection of d-lactate was performed by chronoamperometry and took advantage of the constant potential oxidation of NADH, formed in the reaction catalysed by d-lactate dehydrogenase.

Analytical Letters, 2001

A disposable monoenzymatic sensor for the reliable determination of dithiocarbamate fungicides wa... more A disposable monoenzymatic sensor for the reliable determination of dithiocarbamate fungicides was developed based on aldehyde dehydrogenase inhibition. Aldehyde dehydrogenase was immobilized on the surface of a disposable screen-printed carbon-paste electrode by using a photocross linkable poly-(vinylalcohol) bearing styrylpyridinium groups. Electrochemical oxidation of NADH was carried out at a potential as low as 0V vs Ag/AgCl using Meldola’s Blue as

A multivariate data analysis, partial least-squares regression (PLS) was performed on chronoamper... more A multivariate data analysis, partial least-squares regression (PLS) was performed on chronoamperometric data. These data were obtained using a disposable screen-printed NAD + -dependent dehydrogenase biosensor suited to determine propionaldehyde concentration. The influence of several data pre-treatments on prediction ability of the built PLS models was studied. Propionaldehyde determination was efficiently achieved for concentrations ranging from 0.2 to 1.2 mM using a model with six significant latent variables. Treatment of the overall chronoamperometric data (using PLS regression) compared to regression on a single data point of chronoamperograms improved substrate determination reliability: the overall coefficient of variation for the determination of propionaldehyde was reduced from 33 to 15%. This study opened up opportunities for further developments of disposable sensors for field use.

Trends in Analytical Chemistry, 2007

Mycotoxins are secondary metabolites that moulds produce naturally. Due to their ubiquitous prese... more Mycotoxins are secondary metabolites that moulds produce naturally. Due to their ubiquitous presence in foodstuffs and their potential risk for human health, prompt detection is important. In this review, we present and critically compare recent advances in mycotoxin analysis. Although most validated detection methods are chromatographic, alternative strategies based on biosensing principles are emerging. Biosensors and sensor arrays provide selective,

An amperometric biosensor based on malate quinone oxidoreductase (MQO) was developed for monitori... more An amperometric biosensor based on malate quinone oxidoreductase (MQO) was developed for monitoring of the malolactic fermentation of wines. Screen-printed electrodes coupled with appropriate mediators were used as transducers for this novel biosensor. MQO was immobilized by physical entrapment in a photo-cross-linkable poly(vinyl alcohol) polymer (PVA-SbQ) on the surface of the working electrode. Several electrochemical mediators were studied in order to lower the applied potential and minimise the matrix effects. Among them, 2,6-dichlorophenol indophenol (DPIP) and phenazine methosulfate (PMS) were chosen for further development. The working conditions (mediator concentration, applied potential and pH) were optimised for both DPIP and PMS. Detection limits for both types of biosensors were of 5 M malic acid. Sensitivities obtained for the linear part of the calibration curve were 0.85 and 1.7 mA/M for the biosensors based on DPIP and PMS, respectively. Interferences due to non-specific oxidations were shown to be negligible when using PMS as mediator.

Analytical and Bioanalytical Chemistry, 2002

Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in bio... more Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in biosensors based on NAD(+)-dependent dehydrogenases, tyrosinase, or genetically modified acetylcholinesterases. The mono-enzyme sensors have been optimized as disposable or reusable devices for detection of a variety of substrates important in the food industry ( D-lactic acid, L-lactic acid, acetaldehyde) or in environmental pollution control (phenols and dithiocarbamate, carbamate and organophosphorus pesticides). The sensors were prepared in four configurations differing in enzyme confinement, enzyme immobilization and location of the immobilization agent in the biosensor assembly. Tests on real samples have been performed with the biosensors; D-lactic acid and acetaldehyde have been detected in wine and phenols in air.

The inhibition sensitivity of wild and mutant acetylcholinesterases (AChE) towards selected organ... more The inhibition sensitivity of wild and mutant acetylcholinesterases (AChE) towards selected organophosphorus pesticides has been compared with enzymes immobilized in a photocured layer of polyvinylalcohol polymer (PVA-AWP) on a screen-printed graphite electrode. The investigated pesticides included the widely used malaoxon (MO), chlorfenvinphos (CFV), and chlorpyriphos-oxon (CPO). The last two insecticides are in the EC priority list of toxic compounds to be detected in water. The limits of detection (LOD) obtained with each pesticide tested were in accordance with the European regulation.

Advances in Experimental Medicine and Biology, 2010

T he food industries need rapid and affordable methods to assure: the quality of products and pro... more T he food industries need rapid and affordable methods to assure: the quality of products and process control. Bioscnsors, combining a biological recognition element and a sensitive cransducer, are versatile analytical tools that offer advantages all classical analytical methods due to their inherent specificity, selectivity and simplicity. This paper reviews the recent trends in the development and applications ofbioscnsors used in food fermentation industry. focusing on ampcromctric enzymatic and microbial sensors.

Plant 4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of a range of synthetic ... more Plant 4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of a range of synthetic βtriketone herbicides that are currently used commercially. Their mode of action is based on an irreversible inhibition of HPPD. Therefore, this inhibitory capacity was used to develop a whole-cell colorimetric bioassay with a recombinant Escherichia coli expressing a plant HPPD for the herbicide analysis of β-triketones. The principle of the bioassay is based on the ability of the recombinant E. coli clone to produce a soluble melanin-like pigment, from tyrosine catabolism through p-hydroxyphenylpyruvate and homogentisate. The addition of sulcotrione, a HPPD inhibitor, decreased the pigment production. With the aim to optimize the assay, the E. coli recombinant clone was immobilized in sol-gel or agarose matrix in a 96-well microplate format. The limit of detection for mesotrione, tembotrione, sulcotrione, and leptospermone was 0.069, 0.051, 0.038, and 20 μM, respectively, allowing to validate the whole-cell colorimetric bioassay as a simple and cost-effective alternative tool for laboratory use. The bioassay results from sulcotrione-spiked soil samples were confirmed with high-performance liquid chromatography.

Journal of Sensors, 2011

A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive mat... more A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive material to be incorporated in acetylcholinesterase-(AChE-) based screen printed biosensors, acting not only as a conducting template but also as an electrochemical mediator for thiocholine oxidation. Two different strategies have been studied for the chemical synthesis of PEDOT: (a) a classical oxidative polymerisation and (b) a more innovative enzymatic polymerisation, giving a water-soluble PEDOT. The use of this water-soluble conducting polymer as mediator in screen-printed biosensors enables its deposition by printing like the rest of the layers. Highly sensitive acetylcholinesterase-(AChE-) based screen-printed biosensors have been constructed using both classical and enzymatic PEDOT, in combination with genetically modified AChE. These electrodes allow the measurement of thiocholine oxidation at potentials of 100 mV versus Ag/AgCl reference electrode through the mediation of PEDOT. Inhibition of thiocholine production in presence of CPO allow for detection of this pesticide in concentrations as low as 1·10 −10 M.

Talanta, 2014

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing ... more We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples.

Field Analytical Chemistry & Technology, 1999

The dithiocarbamate fungicides and the organophosphorus and carbamate insecticides are two famili... more The dithiocarbamate fungicides and the organophosphorus and carbamate insecticides are two families of pesticides of environmental concern used on a very large scale worldwide. The need for increasing numbers of analyses has created a demand for the development of rapid, simple, and low cost methods. Enzyme sensors based on the abilities of these compounds to inhibit enzymes are described. An enzyme sensor with immobilized aldehyde dehydrogenase is described allowing the detection of 9 ppb of zineb, whereas the classical method allows the determination of 400 ppb. Using screen-printed electrodes with acetylcholinesterase, it is possible to detect 0.5 ppb of paraoxon in aqueous buffer and 1.4 ppb of paraoxon in a mixture of hexane and water (80/20).

Talanta, 2003

Three strategies have been compared to produce screen-printed amperometric detectors for NADH: mi... more Three strategies have been compared to produce screen-printed amperometric detectors for NADH: mixing Meldola Blue (MB) in the screen-printing ink, incorporation of MB Á/Reinecke salt (MBRS) in the graphite ink and electrodeposition of films of MB-derived polymer (poly (MB)) on electrode surface. Following modification of graphite electrodes the mediators displayed values of the formal potential E 8? from (/0.129 to (/0.160 V vs. Ag/AgCl and pK a s of 5.09 Á/6.02. A second redox couple with E 8?0/(/0.450 V vs. Ag/AgCl was observed in cyclic voltammetry experiments with poly (MB) sensors or with old electrodes obtained according to the other two strategies. Electropolymerisation of MB allowed to achieve the best operational stability and best detection limit, 2 )/10 (6 M, for amperometric detection of NADH, while the most extended linear range, 1 )/10 (5 Á/7.5)/10 (4 M, corresponds to sensors with MBRS. MB and MBRS electrodes were compared with a similar NADH detector produced by Gwent Electronic Materials, England. Several characteristics of the modified-electrodes induced by the fabrication by screenprinting were also highlighted. #

Biosensors and Bioelectronics, 2003

Electropolymerization of Meldola Blue was carried out by cyclic voltammetry in the range from (/0... more Electropolymerization of Meldola Blue was carried out by cyclic voltammetry in the range from (/0.6 to '/1.4 V vs. Ag/AgCl, thus defining a new immobilization procedure of the phenoxazine mediator on screen-printed graphite electrodes. Evidence of polymer formation was provided by electrochemical and Fourier transform infrared spectroscopy (FTIR) data. Following polymerization, Meldola Blue preserved the ability to catalyze NADH oxidation allowing to achieve a detection limit of 2.5 )/10 (6 mol l (1 and a sensitivity of 3713 mA l mol (1 in amperometric determinations at 0 V vs. Ag/AgCl. In addition, the polymeric mediator was found to facilitate the reduction of hydrogen peroxide in the absence of peroxidase. Typical calibration at (/0.1 V vs. Ag/AgCl shows a detection limit of 8.5 )/10 (5 mol l (1 , a sensitivity of 494 mA l mol (1 and a linear range from 2.5 )/10 (4 to 5 )/ 10 (3 mol l (1 hydrogen peroxide. #

Analytica Chimica Acta, 2002

Biosensors for d-lactate and acetaldehyde were developed, based on screen-printed electrodes and ... more Biosensors for d-lactate and acetaldehyde were developed, based on screen-printed electrodes and NAD + -dependent dehydrogenases. Modification of screen-printed electrodes with the mediator Meldola Blue or with Meldola Blue-Reinecke salt resulted in sensitive, low cost and reliable NADH detectors. The biosensors were realised in two configurations, as disposable and reusable devices. Single-use sensors were obtained by simple deposition of enzyme and cofactor on the surface of mediator-modified electrodes. Chronoamperometry was used for the detection of substrates in small volumes of samples (25 l). Immobilisation of dehydrogenases by entrapment in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) allowed sensors to be obtained with sufficient operational stability. Amperometry in stirred solutions was the detection technique with biosensors for multiple use. The 3σ detection limits for acetaldehyde were 1 M by amperometry and 6 M by chronoamperometry and for d-lactate-0.03 M and 0.05 M for reusable and disposable biosensors respectively.

Journal of AOAC International

A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The senso... more A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The sensor is based on the association of screen-printed carbon electrodes and aldehyde dehydrogenase immobilized by a sol-gel entrapment method. Modification of screen-printed carbon electrodes with Reinecke salt of Meldola's Blue (MBRS) resulted in highly sensitive and interference-free nicotinamide-adenine dinucleotide (NADH) detectors. Based on MBRS-mediated oxidation of NADH at -150 mV versus pseudo Ag/AgCl, acetaldehyde was determined in the range 10-260 microM, compatible with wine quality monitoring. The method of immobilization based on sol-gel entrapment was optimized to obtain the best compromise between sensitivity and operational stability. The sensor response was stable for 40 consecutive assays with methyltrimethoxysilane used as alkoxide precursor, thus allowing a possible calibration of the sensor before each measurement. The biosensors were used to analyze French wines. The method was validated with a commercially available enzymatic kit based on a standard spectrophotometric method.

Analytical and Bioanalytical Chemistry, 2002

Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in bio... more Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in biosensors based on NAD + -dependent dehydrogenases, tyrosinase, or genetically modified acetylcholinesterases. The mono-enzyme sensors have been optimized as disposable or reusable devices for detection of a variety of substrates important in the food industry (D-lactic acid, L-lactic acid, acetaldehyde) or in environmental pollution control (phenols and dithiocarbamate, carbamate and organophosphorus pesticides). The sensors were prepared in four configurations differing in enzyme confinement, enzyme immobilization and location of the immobilization agent in the biosensor assembly. Tests on real samples have been performed with the biosensors; D-lactic acid and acetaldehyde have been detected in wine and phenols in air.

Analytica Chimica Acta, 2001

A reagentless biosensor for d-lactate was developed using the screen-printing technology. In a si... more A reagentless biosensor for d-lactate was developed using the screen-printing technology. In a simple design, d-lactate dehydrogenase and NAD + were deposited onto the surface of a carbon electrode, modified with an insoluble salt of Meldola's Blue. The detection of d-lactate was performed by chronoamperometry and took advantage of the constant potential oxidation of NADH, formed in the reaction catalysed by d-lactate dehydrogenase.

Analytical Letters, 2001

A disposable monoenzymatic sensor for the reliable determination of dithiocarbamate fungicides wa... more A disposable monoenzymatic sensor for the reliable determination of dithiocarbamate fungicides was developed based on aldehyde dehydrogenase inhibition. Aldehyde dehydrogenase was immobilized on the surface of a disposable screen-printed carbon-paste electrode by using a photocross linkable poly-(vinylalcohol) bearing styrylpyridinium groups. Electrochemical oxidation of NADH was carried out at a potential as low as 0V vs Ag/AgCl using Meldola’s Blue as

A multivariate data analysis, partial least-squares regression (PLS) was performed on chronoamper... more A multivariate data analysis, partial least-squares regression (PLS) was performed on chronoamperometric data. These data were obtained using a disposable screen-printed NAD + -dependent dehydrogenase biosensor suited to determine propionaldehyde concentration. The influence of several data pre-treatments on prediction ability of the built PLS models was studied. Propionaldehyde determination was efficiently achieved for concentrations ranging from 0.2 to 1.2 mM using a model with six significant latent variables. Treatment of the overall chronoamperometric data (using PLS regression) compared to regression on a single data point of chronoamperograms improved substrate determination reliability: the overall coefficient of variation for the determination of propionaldehyde was reduced from 33 to 15%. This study opened up opportunities for further developments of disposable sensors for field use.

Trends in Analytical Chemistry, 2007

Mycotoxins are secondary metabolites that moulds produce naturally. Due to their ubiquitous prese... more Mycotoxins are secondary metabolites that moulds produce naturally. Due to their ubiquitous presence in foodstuffs and their potential risk for human health, prompt detection is important. In this review, we present and critically compare recent advances in mycotoxin analysis. Although most validated detection methods are chromatographic, alternative strategies based on biosensing principles are emerging. Biosensors and sensor arrays provide selective,

An amperometric biosensor based on malate quinone oxidoreductase (MQO) was developed for monitori... more An amperometric biosensor based on malate quinone oxidoreductase (MQO) was developed for monitoring of the malolactic fermentation of wines. Screen-printed electrodes coupled with appropriate mediators were used as transducers for this novel biosensor. MQO was immobilized by physical entrapment in a photo-cross-linkable poly(vinyl alcohol) polymer (PVA-SbQ) on the surface of the working electrode. Several electrochemical mediators were studied in order to lower the applied potential and minimise the matrix effects. Among them, 2,6-dichlorophenol indophenol (DPIP) and phenazine methosulfate (PMS) were chosen for further development. The working conditions (mediator concentration, applied potential and pH) were optimised for both DPIP and PMS. Detection limits for both types of biosensors were of 5 M malic acid. Sensitivities obtained for the linear part of the calibration curve were 0.85 and 1.7 mA/M for the biosensors based on DPIP and PMS, respectively. Interferences due to non-specific oxidations were shown to be negligible when using PMS as mediator.

Analytical and Bioanalytical Chemistry, 2002

Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in bio... more Graphite electrodes fabricated by screen-printing have been used as amperometric detectors in biosensors based on NAD(+)-dependent dehydrogenases, tyrosinase, or genetically modified acetylcholinesterases. The mono-enzyme sensors have been optimized as disposable or reusable devices for detection of a variety of substrates important in the food industry ( D-lactic acid, L-lactic acid, acetaldehyde) or in environmental pollution control (phenols and dithiocarbamate, carbamate and organophosphorus pesticides). The sensors were prepared in four configurations differing in enzyme confinement, enzyme immobilization and location of the immobilization agent in the biosensor assembly. Tests on real samples have been performed with the biosensors; D-lactic acid and acetaldehyde have been detected in wine and phenols in air.

The inhibition sensitivity of wild and mutant acetylcholinesterases (AChE) towards selected organ... more The inhibition sensitivity of wild and mutant acetylcholinesterases (AChE) towards selected organophosphorus pesticides has been compared with enzymes immobilized in a photocured layer of polyvinylalcohol polymer (PVA-AWP) on a screen-printed graphite electrode. The investigated pesticides included the widely used malaoxon (MO), chlorfenvinphos (CFV), and chlorpyriphos-oxon (CPO). The last two insecticides are in the EC priority list of toxic compounds to be detected in water. The limits of detection (LOD) obtained with each pesticide tested were in accordance with the European regulation.

Advances in Experimental Medicine and Biology, 2010

T he food industries need rapid and affordable methods to assure: the quality of products and pro... more T he food industries need rapid and affordable methods to assure: the quality of products and process control. Bioscnsors, combining a biological recognition element and a sensitive cransducer, are versatile analytical tools that offer advantages all classical analytical methods due to their inherent specificity, selectivity and simplicity. This paper reviews the recent trends in the development and applications ofbioscnsors used in food fermentation industry. focusing on ampcromctric enzymatic and microbial sensors.

Plant 4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of a range of synthetic ... more Plant 4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of a range of synthetic βtriketone herbicides that are currently used commercially. Their mode of action is based on an irreversible inhibition of HPPD. Therefore, this inhibitory capacity was used to develop a whole-cell colorimetric bioassay with a recombinant Escherichia coli expressing a plant HPPD for the herbicide analysis of β-triketones. The principle of the bioassay is based on the ability of the recombinant E. coli clone to produce a soluble melanin-like pigment, from tyrosine catabolism through p-hydroxyphenylpyruvate and homogentisate. The addition of sulcotrione, a HPPD inhibitor, decreased the pigment production. With the aim to optimize the assay, the E. coli recombinant clone was immobilized in sol-gel or agarose matrix in a 96-well microplate format. The limit of detection for mesotrione, tembotrione, sulcotrione, and leptospermone was 0.069, 0.051, 0.038, and 20 μM, respectively, allowing to validate the whole-cell colorimetric bioassay as a simple and cost-effective alternative tool for laboratory use. The bioassay results from sulcotrione-spiked soil samples were confirmed with high-performance liquid chromatography.

Journal of Sensors, 2011

A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive mat... more A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive material to be incorporated in acetylcholinesterase-(AChE-) based screen printed biosensors, acting not only as a conducting template but also as an electrochemical mediator for thiocholine oxidation. Two different strategies have been studied for the chemical synthesis of PEDOT: (a) a classical oxidative polymerisation and (b) a more innovative enzymatic polymerisation, giving a water-soluble PEDOT. The use of this water-soluble conducting polymer as mediator in screen-printed biosensors enables its deposition by printing like the rest of the layers. Highly sensitive acetylcholinesterase-(AChE-) based screen-printed biosensors have been constructed using both classical and enzymatic PEDOT, in combination with genetically modified AChE. These electrodes allow the measurement of thiocholine oxidation at potentials of 100 mV versus Ag/AgCl reference electrode through the mediation of PEDOT. Inhibition of thiocholine production in presence of CPO allow for detection of this pesticide in concentrations as low as 1·10 −10 M.

Talanta, 2014

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing ... more We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples.

Field Analytical Chemistry & Technology, 1999

The dithiocarbamate fungicides and the organophosphorus and carbamate insecticides are two famili... more The dithiocarbamate fungicides and the organophosphorus and carbamate insecticides are two families of pesticides of environmental concern used on a very large scale worldwide. The need for increasing numbers of analyses has created a demand for the development of rapid, simple, and low cost methods. Enzyme sensors based on the abilities of these compounds to inhibit enzymes are described. An enzyme sensor with immobilized aldehyde dehydrogenase is described allowing the detection of 9 ppb of zineb, whereas the classical method allows the determination of 400 ppb. Using screen-printed electrodes with acetylcholinesterase, it is possible to detect 0.5 ppb of paraoxon in aqueous buffer and 1.4 ppb of paraoxon in a mixture of hexane and water (80/20).