The Experts below are selected from a list of 738 Experts worldwide ranked by ideXlab platform
Camelia Bala - One of the best experts on this subject based on the ideXlab platform.
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acetylcholinesterase biosensor for carbamate drugs based on tetrathiafulvalene tetracyanoquinodimethane ionic liquid conductive gels
Biosensors and Bioelectronics, 2013Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:Abstract A highly sensitive acetylcholinesterase biosensor was developed for detection of carbamate drugs based on TTF–TCNQ–ionic liquid gel Thiocholine sensor. The TTF–TCNQ–ionic/ionic liquid gel was characterized by FT-IR and scanning electron microscopy. The electrocatalytic behavior of TTF–TCNQ–ionic liquid gels toward oxidation of Thiocholine was thoroughly investigated. 1-Ethyl-3-methylimidazolium tetracyanoborate gel based sensor allowed amperometric detection of Thiocholine at +400 mV vs. Ag/AgCl with a high sensitivity of 55.9±1.2 μA mM −1 cm −2 and a low detection limit equal to 7.6 μM. The catalytic rate constant and diffusion constant of Thiocholine were estimated from chronoamperometric data. The proposed biosensor based on AChE immobilized in sol–gel matrix was used for the detection of two carbamate therapeutic drugs. Very low detection limits of 26 pM eserine and 0.3 nM neostigmine were achieved. The analysis of spiked tap water proved the biosensor capability to be used as a screening method for detection of carbamate drugs in wastewaters.
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a novel sensitive reusable and low potential acetylcholinesterase biosensor for chlorpyrifos based on 1 butyl 3 methylimidazolium tetrafluoroborate multiwalled carbon nanotubes gel
Biosensors and Bioelectronics, 2011Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:A novel, low potential and highly sensitive acetylcholinesterase (AChE) biosensor was developed based on 1-butyl-3-methylimidazolium tetrafluoroborate/multiwalled carbon nanotube composite gel Thiocholine sensor. Composite gel promoted electron transfer reaction at a lower potential (+50 mV) and catalyzed electrochemical oxidation of Thiocholine with high sensitivity. AChE was immobilized in sol-gel matrix that provides a good support for enzyme without any inhibition effect from the ionic liquid. The amount of immobilized enzyme and incubation time with chlorpyrifos were optimized. Chlorpyrifos could be determined in the range of 10(-8)-10(-6)M with a detection limit of 4 nM. Fast and efficient enzyme reactivation was obtained at low obidoxime concentration (0.1mM). Moreover, the biosensor exhibited a good stability and reproducibility and could be use for multiple determinations of pesticide with no loss of the enzyme activity.
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low potential Thiocholine oxidation at carbon nanotube ionic liquid gel sensor
Sensors and Actuators B-chemical, 2010Co-Authors: Lucian Rotariu, Luciangabriel Zamfir, Camelia BalaAbstract:Abstract Low-potential Thiocholine (TCh) detection was achieved at ionic liquid–multi-walled carbon nanotube (IL–MWCNT) modified electrodes. Cyclic voltammetry and amperometric characteristics of eight different Thiocholine sensors were compared. With an oxidation potential between 0 and +50 mV ( vs . Ag/AgCl) [EMIM][OTF]-, [EMIM][NTF 2 ]-, [EMIM][TCB]- and [BMIM][BF 4 ]–MWCNT gels offer a substantial decrease of the working potential comparing with other types of Thiocholine sensors. Correlation between the physical properties and electrochemical behaviour of IL–MWCNT gels is also reported. Electrochemical impedance spectroscopy (EIS) and pH-dependence experiments suggest the existence of an electrostratic interaction between Thiocholine and composite gels which favours the electrochemical reaction. The catalytical rate constant and the diffusion coefficient of Thiocholine were calculated from chronoamperometric data. A very good sensitivity between 36 and 45 μA/mM cm 2 was achieved for acetylThiocholine detection using selected gel-modified sensors.
Luciangabriel Zamfir - One of the best experts on this subject based on the ideXlab platform.
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acetylcholinesterase biosensor for carbamate drugs based on tetrathiafulvalene tetracyanoquinodimethane ionic liquid conductive gels
Biosensors and Bioelectronics, 2013Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:Abstract A highly sensitive acetylcholinesterase biosensor was developed for detection of carbamate drugs based on TTF–TCNQ–ionic liquid gel Thiocholine sensor. The TTF–TCNQ–ionic/ionic liquid gel was characterized by FT-IR and scanning electron microscopy. The electrocatalytic behavior of TTF–TCNQ–ionic liquid gels toward oxidation of Thiocholine was thoroughly investigated. 1-Ethyl-3-methylimidazolium tetracyanoborate gel based sensor allowed amperometric detection of Thiocholine at +400 mV vs. Ag/AgCl with a high sensitivity of 55.9±1.2 μA mM −1 cm −2 and a low detection limit equal to 7.6 μM. The catalytic rate constant and diffusion constant of Thiocholine were estimated from chronoamperometric data. The proposed biosensor based on AChE immobilized in sol–gel matrix was used for the detection of two carbamate therapeutic drugs. Very low detection limits of 26 pM eserine and 0.3 nM neostigmine were achieved. The analysis of spiked tap water proved the biosensor capability to be used as a screening method for detection of carbamate drugs in wastewaters.
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a novel sensitive reusable and low potential acetylcholinesterase biosensor for chlorpyrifos based on 1 butyl 3 methylimidazolium tetrafluoroborate multiwalled carbon nanotubes gel
Biosensors and Bioelectronics, 2011Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:A novel, low potential and highly sensitive acetylcholinesterase (AChE) biosensor was developed based on 1-butyl-3-methylimidazolium tetrafluoroborate/multiwalled carbon nanotube composite gel Thiocholine sensor. Composite gel promoted electron transfer reaction at a lower potential (+50 mV) and catalyzed electrochemical oxidation of Thiocholine with high sensitivity. AChE was immobilized in sol-gel matrix that provides a good support for enzyme without any inhibition effect from the ionic liquid. The amount of immobilized enzyme and incubation time with chlorpyrifos were optimized. Chlorpyrifos could be determined in the range of 10(-8)-10(-6)M with a detection limit of 4 nM. Fast and efficient enzyme reactivation was obtained at low obidoxime concentration (0.1mM). Moreover, the biosensor exhibited a good stability and reproducibility and could be use for multiple determinations of pesticide with no loss of the enzyme activity.
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low potential Thiocholine oxidation at carbon nanotube ionic liquid gel sensor
Sensors and Actuators B-chemical, 2010Co-Authors: Lucian Rotariu, Luciangabriel Zamfir, Camelia BalaAbstract:Abstract Low-potential Thiocholine (TCh) detection was achieved at ionic liquid–multi-walled carbon nanotube (IL–MWCNT) modified electrodes. Cyclic voltammetry and amperometric characteristics of eight different Thiocholine sensors were compared. With an oxidation potential between 0 and +50 mV ( vs . Ag/AgCl) [EMIM][OTF]-, [EMIM][NTF 2 ]-, [EMIM][TCB]- and [BMIM][BF 4 ]–MWCNT gels offer a substantial decrease of the working potential comparing with other types of Thiocholine sensors. Correlation between the physical properties and electrochemical behaviour of IL–MWCNT gels is also reported. Electrochemical impedance spectroscopy (EIS) and pH-dependence experiments suggest the existence of an electrostratic interaction between Thiocholine and composite gels which favours the electrochemical reaction. The catalytical rate constant and the diffusion coefficient of Thiocholine were calculated from chronoamperometric data. A very good sensitivity between 36 and 45 μA/mM cm 2 was achieved for acetylThiocholine detection using selected gel-modified sensors.
Lucian Rotariu - One of the best experts on this subject based on the ideXlab platform.
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acetylcholinesterase biosensor for carbamate drugs based on tetrathiafulvalene tetracyanoquinodimethane ionic liquid conductive gels
Biosensors and Bioelectronics, 2013Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:Abstract A highly sensitive acetylcholinesterase biosensor was developed for detection of carbamate drugs based on TTF–TCNQ–ionic liquid gel Thiocholine sensor. The TTF–TCNQ–ionic/ionic liquid gel was characterized by FT-IR and scanning electron microscopy. The electrocatalytic behavior of TTF–TCNQ–ionic liquid gels toward oxidation of Thiocholine was thoroughly investigated. 1-Ethyl-3-methylimidazolium tetracyanoborate gel based sensor allowed amperometric detection of Thiocholine at +400 mV vs. Ag/AgCl with a high sensitivity of 55.9±1.2 μA mM −1 cm −2 and a low detection limit equal to 7.6 μM. The catalytic rate constant and diffusion constant of Thiocholine were estimated from chronoamperometric data. The proposed biosensor based on AChE immobilized in sol–gel matrix was used for the detection of two carbamate therapeutic drugs. Very low detection limits of 26 pM eserine and 0.3 nM neostigmine were achieved. The analysis of spiked tap water proved the biosensor capability to be used as a screening method for detection of carbamate drugs in wastewaters.
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a novel sensitive reusable and low potential acetylcholinesterase biosensor for chlorpyrifos based on 1 butyl 3 methylimidazolium tetrafluoroborate multiwalled carbon nanotubes gel
Biosensors and Bioelectronics, 2011Co-Authors: Luciangabriel Zamfir, Lucian Rotariu, Camelia BalaAbstract:A novel, low potential and highly sensitive acetylcholinesterase (AChE) biosensor was developed based on 1-butyl-3-methylimidazolium tetrafluoroborate/multiwalled carbon nanotube composite gel Thiocholine sensor. Composite gel promoted electron transfer reaction at a lower potential (+50 mV) and catalyzed electrochemical oxidation of Thiocholine with high sensitivity. AChE was immobilized in sol-gel matrix that provides a good support for enzyme without any inhibition effect from the ionic liquid. The amount of immobilized enzyme and incubation time with chlorpyrifos were optimized. Chlorpyrifos could be determined in the range of 10(-8)-10(-6)M with a detection limit of 4 nM. Fast and efficient enzyme reactivation was obtained at low obidoxime concentration (0.1mM). Moreover, the biosensor exhibited a good stability and reproducibility and could be use for multiple determinations of pesticide with no loss of the enzyme activity.
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low potential Thiocholine oxidation at carbon nanotube ionic liquid gel sensor
Sensors and Actuators B-chemical, 2010Co-Authors: Lucian Rotariu, Luciangabriel Zamfir, Camelia BalaAbstract:Abstract Low-potential Thiocholine (TCh) detection was achieved at ionic liquid–multi-walled carbon nanotube (IL–MWCNT) modified electrodes. Cyclic voltammetry and amperometric characteristics of eight different Thiocholine sensors were compared. With an oxidation potential between 0 and +50 mV ( vs . Ag/AgCl) [EMIM][OTF]-, [EMIM][NTF 2 ]-, [EMIM][TCB]- and [BMIM][BF 4 ]–MWCNT gels offer a substantial decrease of the working potential comparing with other types of Thiocholine sensors. Correlation between the physical properties and electrochemical behaviour of IL–MWCNT gels is also reported. Electrochemical impedance spectroscopy (EIS) and pH-dependence experiments suggest the existence of an electrostratic interaction between Thiocholine and composite gels which favours the electrochemical reaction. The catalytical rate constant and the diffusion coefficient of Thiocholine were calculated from chronoamperometric data. A very good sensitivity between 36 and 45 μA/mM cm 2 was achieved for acetylThiocholine detection using selected gel-modified sensors.
Valeri Pavlov - One of the best experts on this subject based on the ideXlab platform.
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blocked enzymatic etching of gold nanorods application to colorimetric detection of acetylcholinesterase activity and its inhibitors
ACS Applied Materials & Interfaces, 2016Co-Authors: Laura Saa, Luis M Lizmarzan, Ruta Grinyte, Ana Sancheziglesias, Valeri PavlovAbstract:The anisotropic morphology of gold nanorods (AuNRs) has been shown to lead to nonuniform ligand distribution and preferential etching through their tips. We have recently demonstrated that this effect can be achieved by biocatalytic oxidation with hydrogen peroxide, catalyzed by the enzyme horseradish peroxidase (HRP). We report here that modification of AuNRs with thiol-containing organic molecules such as glutathione and Thiocholine hinders enzymatic AuNR etching. Higher concentrations of thiol-containing molecules in the reaction mixture gradually decrease the rate of enzymatic etching, which can be monitored by UV–vis spectroscopy through changes in the AuNR longitudinal plasmon band. This effect can be applied to develop novel optical assays for acetylcholinesterase (AChE) activity. The biocatalytic hydrolysis of acetylThiocholine by AChE yields Thiocholine, which prevents enzymatic AuNR etching in the presence of HRP. Additionally, the same bioassay can be used for the detection of nanomolar concent...
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Blocked Enzymatic Etching of Gold Nanorods: Application to Colorimetric Detection of Acetylcholinesterase Activity and Its Inhibitors
2016Co-Authors: Laura Saa, Ruta Grinyte, Ana Sánchez-iglesias, Luis M. Liz-marzán, Valeri PavlovAbstract:The anisotropic morphology of gold nanorods (AuNRs) has been shown to lead to nonuniform ligand distribution and preferential etching through their tips. We have recently demonstrated that this effect can be achieved by biocatalytic oxidation with hydrogen peroxide, catalyzed by the enzyme horseradish peroxidase (HRP). We report here that modification of AuNRs with thiol-containing organic molecules such as glutathione and Thiocholine hinders enzymatic AuNR etching. Higher concentrations of thiol-containing molecules in the reaction mixture gradually decrease the rate of enzymatic etching, which can be monitored by UV–vis spectroscopy through changes in the AuNR longitudinal plasmon band. This effect can be applied to develop novel optical assays for acetylcholinesterase (AChE) activity. The biocatalytic hydrolysis of acetylThiocholine by AChE yields Thiocholine, which prevents enzymatic AuNR etching in the presence of HRP. Additionally, the same bioassay can be used for the detection of nanomolar concentrations of AChE inhibitors such as paraoxon and galanthamine
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enzymatic modulation of gold nanorod growth and application to nerve gas detection
Nano Today, 2013Co-Authors: Marc Coronadopuchau, Valeri Pavlov, Laura Saa, Marek Grzelczak, Luis M LizmarzanAbstract:Summary The seed mediated growth of gold nanorods can be affected by a variety of reactant parameters, mainly through adsorption of different moieties onto the metal surface. We describe the modulation of nanorod growth through the addition of an enzymatically-produced thiolated molecule. The enzyme acetylcholinesterase was selected because it hydrolyzes the substrate acetylThiocholine to produce the thiol-containing molecule Thiocholine, in a controlled manner. UV–vis spectroscopic monitoring showed that the resulting localized surface plasmon resonance bands of the formed colloidal nanoparticles are highly sensitive to the concentration of Thiocholine, while transmission electron microscopy allowed us to confirm that the observed optical changes arise from the evolution of the shape of the obtained gold nanoparticles from nanorods to cubes and finally to spheres, upon increasing the concentration of Thiocholine. Hence, enzyme concentrations could be correlated with different plasmon bands and/or gold nanoparticle shapes. On the basis of this result, a simple colorimetric assay is proposed for the detection of subnanomolar concentrations of acetylcholinesterase inhibitors, which are close analogs of nerve gases.
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inhibition of the acetycholine esterase stimulated growth of au nanoparticles nanotechnology based sensing of nerve gases
Nano Letters, 2005Co-Authors: Valeri Pavlov, Yi Xiao, Itamar WillnerAbstract:The acetylcholine esterase, AChE, mediated hydrolysis of acetylThiocholine (1) yields a reducing agent Thiocholine (2) that stimulates the catalytic enlargement of Au NP seeds in the presence of AuCl4-. The reductive enlargement of the Au NPs is controlled by the concentration of the substrate (1) and by the activity of the enzyme. The catalytic growth of the Au NPs is inhibited by 1,5-bis(4-allyldimethylammoniumphenyl)pentane-3-one dibromide (3) or by diethyl p-nitrophenyl phosphate (paraoxon; 4), thus enabling a colorimetric test for AChE inhibitors. The colorimetric assay was also developed on glass supports.
Luis M Lizmarzan - One of the best experts on this subject based on the ideXlab platform.
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blocked enzymatic etching of gold nanorods application to colorimetric detection of acetylcholinesterase activity and its inhibitors
ACS Applied Materials & Interfaces, 2016Co-Authors: Laura Saa, Luis M Lizmarzan, Ruta Grinyte, Ana Sancheziglesias, Valeri PavlovAbstract:The anisotropic morphology of gold nanorods (AuNRs) has been shown to lead to nonuniform ligand distribution and preferential etching through their tips. We have recently demonstrated that this effect can be achieved by biocatalytic oxidation with hydrogen peroxide, catalyzed by the enzyme horseradish peroxidase (HRP). We report here that modification of AuNRs with thiol-containing organic molecules such as glutathione and Thiocholine hinders enzymatic AuNR etching. Higher concentrations of thiol-containing molecules in the reaction mixture gradually decrease the rate of enzymatic etching, which can be monitored by UV–vis spectroscopy through changes in the AuNR longitudinal plasmon band. This effect can be applied to develop novel optical assays for acetylcholinesterase (AChE) activity. The biocatalytic hydrolysis of acetylThiocholine by AChE yields Thiocholine, which prevents enzymatic AuNR etching in the presence of HRP. Additionally, the same bioassay can be used for the detection of nanomolar concent...
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enzymatic modulation of gold nanorod growth and application to nerve gas detection
Nano Today, 2013Co-Authors: Marc Coronadopuchau, Valeri Pavlov, Laura Saa, Marek Grzelczak, Luis M LizmarzanAbstract:Summary The seed mediated growth of gold nanorods can be affected by a variety of reactant parameters, mainly through adsorption of different moieties onto the metal surface. We describe the modulation of nanorod growth through the addition of an enzymatically-produced thiolated molecule. The enzyme acetylcholinesterase was selected because it hydrolyzes the substrate acetylThiocholine to produce the thiol-containing molecule Thiocholine, in a controlled manner. UV–vis spectroscopic monitoring showed that the resulting localized surface plasmon resonance bands of the formed colloidal nanoparticles are highly sensitive to the concentration of Thiocholine, while transmission electron microscopy allowed us to confirm that the observed optical changes arise from the evolution of the shape of the obtained gold nanoparticles from nanorods to cubes and finally to spheres, upon increasing the concentration of Thiocholine. Hence, enzyme concentrations could be correlated with different plasmon bands and/or gold nanoparticle shapes. On the basis of this result, a simple colorimetric assay is proposed for the detection of subnanomolar concentrations of acetylcholinesterase inhibitors, which are close analogs of nerve gases.
