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Gopinatha Suresh Kumar - One of the best experts on this subject based on the ideXlab platform.
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exploring the interAction of phenothiAzinium dyes methylene blue new methylene blue Azure A And Azure b with trnAphe spectroscopic thermodynAmic voltAmmetric And moleculAr modeling ApproAch
Physical Chemistry Chemical Physics, 2017Co-Authors: Puja Paul, Soumya Sundar Mati, Subhash Chandra Bhattacharya, Gopinatha Suresh KumarAbstract:This study focuses on the understAnding of the interAction of phenothiAzinium dyes methylene blue (MB), new methylene blue (NMB), Azure A (AZA) And Azure B (AZB) with tRNAPhe with pArticulAr emphAsis on deciphering the mode And energetics of the binding. Strong intercAlAtive binding to tRNAPhe wAs observed for MB, NMB And AZB, bound by A pArtiAl intercAlAtive mode. AZA hAs shown groove binding chArActeristics. From spectroscopic studies binding Affinity vAlues of the order of 105 M−1 were deduced for these dyes; the trend vAried As MB > NMB > AZB > AZA. The binding wAs chArActerized by An increAse of thermAl melting temperAtures And perturbAtion in the circulAr dichroism spectrum of tRNA. All the dyes Acquired opticAl Activity upon binding to tRNA. The binding wAs predominAntly entropy driven with A fAvorAble enthAlpy term thAt increAsed with temperAture in All the cAses. Dissection of the Gibbs energy to polyelectrolytic And non-polyelectrolytic terms reveAled A mAjor role of the non-electrostAtic forces in the binding. The smAll but significAnt heAt cApAcity chAnges And the observed enthAlpy–entropy compensAtion phenomenon confirmed the involvement of multiple weAk non-covAlent forces driving the interAction. The mode of binding wAs confirmed from quenching, viscosity And cyclic voltAmmetric results. Using density functionAl theory, ground stAte optimized structures of the dyes were cAlculAted to provide insight into theoreticAl docking studies to correlAte the experimentAl ApproAches. The modeling results verified the binding locAtion As well As the binding energy of complexAtion. The results mAy provide new insights into the structure–Activity relAtionship useful in the design of effective RNA tArgeted therApeutic Agents.
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spectroscopic studies on the binding interAction of phenothiAzinium dyes Azure A And Azure b to double strAnded rnA polynucleotides
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2016Co-Authors: Asma Yasmeen Khan, Gopinatha Suresh KumarAbstract:AbstrAct This mAnuscript presents spectroscopic chArActerizAtion of the interAction of two phenothiAzinium dyes, Azure A And Azure B with double strAnded (ds) ribonucleic Acids, poly(A).poly(U), poly(C).poly(G) And poly(I).poly(C). AbsorbAnce And fluorescence studies reveAled thAt these dyes bind to the RNAs with binding Affinities of the order 10 6 M −1 to poly(A).poly(U), And 10 5 M −1 to poly(C).poly(G) And poly(I).poly(C), respectively. Fluorescence quenching And viscosity dAtA gAve conclusive evidence for the intercAlAtion of the dyes to these RNA duplexes. CirculAr dichroism results suggested thAt the conformAtion of the RNAs wAs perturbed on interAction And the dyes Acquired strong induced opticAl Activity on binding. Azure B bound to All the three RNAs stronger thAn Azure A And the binding Affinity vAried As poly(A).poly(U) > poly(C).poly(G) > poly(I).poly(C) for both dyes.
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A thermodynAmic investigAtion on the binding of phenothiAzinium dyes Azure A And Azure b to double strAnded rnA polynucleotides
The Journal of Chemical Thermodynamics, 2015Co-Authors: Asma Yasmeen Khan, Gopinatha Suresh KumarAbstract:AbstrAct The thermodynAmics of the reActions of the two phenothiAzinium dyes Azure A And Azure B with the three double strAnded ribonucleic Acids, poly(A).poly(U), poly(C).poly(G), poly(I).poly(C) were investigAted using DSC And ITC. The bound dyes stAbilized the RNAs AgAinst thermAl strAnd sepArAtion. The binding of Azure A to the RNAs wAs predominAntly enthAlpy dominAted while the binding of Azure B wAs fAvoured by both negAtive enthAlpy And fAvourAble entropy chAnges. Although electrostAtic interAction hAd A significAnt role in the binding, non-polyelectrolytic forces dominAted the binding process. The negAtive vAlues of heAt cApAcity chAnges for the binding suggested A substAntiAl hydrophobic contribution to the binding process. The overAll binding Affinity of both the dyes to the RNAs vAried in the order, poly(A).poly(U) > poly(C).poly(G) > poly(I).poly(C).
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photophysicAl And cAlorimetric investigAtion on the structurAl reorgAnizAtion of poly A by phenothiAzinium dyes Azure A And Azure b
Photochemical and Photobiological Sciences, 2014Co-Authors: Puja Paul, Gopinatha Suresh KumarAbstract:Poly(A) hAs significAnt relevAnce to mRNA stAbility, protein synthesis And cAncer biology. The Ability of two phenothiAzinium dyes Azure A (AA) And Azure B (AB) to bind single-strAnded poly(A) wAs studied by spectroscopic And cAlorimetric techniques. Strong binding of the dyes And the higher Affinity of AA over AB were AscertAined from AbsorbAnce And fluorescence experiments. SignificAnt perturbAtion of the circulAr dichroism spectrum of poly(A) in the presence of these molecules with formAtion of induced CD bAnds in the 300–700 nm region wAs observed. Strong emission polArizAtion of the bound dyes And strong energy trAnsfer from the Adenine bAse pAirs of poly(A) suggested intercAlAtive binding to poly(A). IntercAlAtive binding wAs confirmed from fluorescence quenching experiments And wAs predominAntly entropy driven As evidenced from isothermAl titrAtion cAlorimetry dAtA. The negAtive vAlues of heAt cApAcity indicAted involvement of hydrophobic forces And enthAlpy–entropy compensAtion suggested noncovAlent interActions in the complexAtion for both the dyes. Poly(A) formed A self-Assembled structure on the binding of both the dyes thAt wAs more fAvored under higher sAlt conditions. New insights in terms of spectroscopic And thermodynAmic Aspects into the self-structure formAtion of poly(A) by two new phenothiAzinium dyes thAt mAy leAd to structurAl And functionAl dAmAge of mRNA Are reveAled from these studies.
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thermodynAmics of the dnA binding of phenothiAzinium dyes toluidine blue o Azure A And Azure b
The Journal of Chemical Thermodynamics, 2013Co-Authors: Puja Paul, Gopinatha Suresh KumarAbstract:AbstrAct The DNA binding of toluidine blue O (TBO), Azure A And Azure B wAs chArActerised by isothermAl titrAtion cAlorimetry, differentiAl scAnning cAlorimetry And thermAl melting studies. The DNA binding Affinity of TBO wAs the highest followed by Azure A And Azure B. The binding in eAch cAse wAs exothermic with A positive entropy chAnge. The Affinity of the binding decreAsed As the [NA + ] concentrAtion increAsed. The non electrostAtic contribution to the stAndArd Gibbs energy remAined the sAme over the rAnge of (10 to 100) mM [NA + ]. The negAtive chAnge in heAt cApAcity of the binding reveAled A substAntiAl hydrophobic contribution in the DNA binding of these dyes. An enthAlpy–entropy compensAtion wAs observed in eAch system. The binding of these dyes stAbilised the DNA AgAinst thermAl strAnd sepArAtion. The energetics of the DNA binding of these dyes correlAte well with the structurAl dAtA thAt suggest their utility As potentiAl DNA tArgeting Agents.
Puja Paul - One of the best experts on this subject based on the ideXlab platform.
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exploring the interAction of phenothiAzinium dyes methylene blue new methylene blue Azure A And Azure b with trnAphe spectroscopic thermodynAmic voltAmmetric And moleculAr modeling ApproAch
Physical Chemistry Chemical Physics, 2017Co-Authors: Puja Paul, Soumya Sundar Mati, Subhash Chandra Bhattacharya, Gopinatha Suresh KumarAbstract:This study focuses on the understAnding of the interAction of phenothiAzinium dyes methylene blue (MB), new methylene blue (NMB), Azure A (AZA) And Azure B (AZB) with tRNAPhe with pArticulAr emphAsis on deciphering the mode And energetics of the binding. Strong intercAlAtive binding to tRNAPhe wAs observed for MB, NMB And AZB, bound by A pArtiAl intercAlAtive mode. AZA hAs shown groove binding chArActeristics. From spectroscopic studies binding Affinity vAlues of the order of 105 M−1 were deduced for these dyes; the trend vAried As MB > NMB > AZB > AZA. The binding wAs chArActerized by An increAse of thermAl melting temperAtures And perturbAtion in the circulAr dichroism spectrum of tRNA. All the dyes Acquired opticAl Activity upon binding to tRNA. The binding wAs predominAntly entropy driven with A fAvorAble enthAlpy term thAt increAsed with temperAture in All the cAses. Dissection of the Gibbs energy to polyelectrolytic And non-polyelectrolytic terms reveAled A mAjor role of the non-electrostAtic forces in the binding. The smAll but significAnt heAt cApAcity chAnges And the observed enthAlpy–entropy compensAtion phenomenon confirmed the involvement of multiple weAk non-covAlent forces driving the interAction. The mode of binding wAs confirmed from quenching, viscosity And cyclic voltAmmetric results. Using density functionAl theory, ground stAte optimized structures of the dyes were cAlculAted to provide insight into theoreticAl docking studies to correlAte the experimentAl ApproAches. The modeling results verified the binding locAtion As well As the binding energy of complexAtion. The results mAy provide new insights into the structure–Activity relAtionship useful in the design of effective RNA tArgeted therApeutic Agents.
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photophysicAl And cAlorimetric investigAtion on the structurAl reorgAnizAtion of poly A by phenothiAzinium dyes Azure A And Azure b
Photochemical and Photobiological Sciences, 2014Co-Authors: Puja Paul, Gopinatha Suresh KumarAbstract:Poly(A) hAs significAnt relevAnce to mRNA stAbility, protein synthesis And cAncer biology. The Ability of two phenothiAzinium dyes Azure A (AA) And Azure B (AB) to bind single-strAnded poly(A) wAs studied by spectroscopic And cAlorimetric techniques. Strong binding of the dyes And the higher Affinity of AA over AB were AscertAined from AbsorbAnce And fluorescence experiments. SignificAnt perturbAtion of the circulAr dichroism spectrum of poly(A) in the presence of these molecules with formAtion of induced CD bAnds in the 300–700 nm region wAs observed. Strong emission polArizAtion of the bound dyes And strong energy trAnsfer from the Adenine bAse pAirs of poly(A) suggested intercAlAtive binding to poly(A). IntercAlAtive binding wAs confirmed from fluorescence quenching experiments And wAs predominAntly entropy driven As evidenced from isothermAl titrAtion cAlorimetry dAtA. The negAtive vAlues of heAt cApAcity indicAted involvement of hydrophobic forces And enthAlpy–entropy compensAtion suggested noncovAlent interActions in the complexAtion for both the dyes. Poly(A) formed A self-Assembled structure on the binding of both the dyes thAt wAs more fAvored under higher sAlt conditions. New insights in terms of spectroscopic And thermodynAmic Aspects into the self-structure formAtion of poly(A) by two new phenothiAzinium dyes thAt mAy leAd to structurAl And functionAl dAmAge of mRNA Are reveAled from these studies.
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thermodynAmics of the dnA binding of phenothiAzinium dyes toluidine blue o Azure A And Azure b
The Journal of Chemical Thermodynamics, 2013Co-Authors: Puja Paul, Gopinatha Suresh KumarAbstract:AbstrAct The DNA binding of toluidine blue O (TBO), Azure A And Azure B wAs chArActerised by isothermAl titrAtion cAlorimetry, differentiAl scAnning cAlorimetry And thermAl melting studies. The DNA binding Affinity of TBO wAs the highest followed by Azure A And Azure B. The binding in eAch cAse wAs exothermic with A positive entropy chAnge. The Affinity of the binding decreAsed As the [NA + ] concentrAtion increAsed. The non electrostAtic contribution to the stAndArd Gibbs energy remAined the sAme over the rAnge of (10 to 100) mM [NA + ]. The negAtive chAnge in heAt cApAcity of the binding reveAled A substAntiAl hydrophobic contribution in the DNA binding of these dyes. An enthAlpy–entropy compensAtion wAs observed in eAch system. The binding of these dyes stAbilised the DNA AgAinst thermAl strAnd sepArAtion. The energetics of the DNA binding of these dyes correlAte well with the structurAl dAtA thAt suggest their utility As potentiAl DNA tArgeting Agents.
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spectroscopic studies on the binding interAction of phenothiAzinium dyes toluidine blue o Azure A And Azure b to dnA
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013Co-Authors: Puja Paul, Gopinatha Suresh KumarAbstract:In this study A detAiled chArActerizAtion of the binding Aspects of three phenothiAzinium dyes, toluidine blue O (TBO), Azure A And Azure B with herring testes DNA is presented employing spectroscopic techniques. The AbsorbAnce And fluorescence properties of these dyes hAve been remArkAbly modified upon binding with DNA And the interAction is mAnifested through noncooperAtive binding As reveAled form non-lineAr ScAtchArd plots with negAtive slopes At All binding rAtios. The binding cleArly reveAled the high preference of TBO to DNA followed by the other two dyes Azure A And Azure B. The Affinity of TBO wAs higher by About two times thAn thAt of the Azures. From the series of studies using Absorption, steAdy-stAte emission, the effect of ferrocyAnide ion-induced steAdy-stAte fluorescence quenching, fluorescence polArizAtion Anisotropy, circulAr dichroism, the mode of binding of these dyes to the DNA double helix hAs been substAntiAted to be principAlly intercAlAtive in nAture. The stoichiometry of the AssociAtion of these dyes to DNA wAs determined by the continuous vAriAtion AnAlysis of Job from fluorescence dAtA. The conformAtionAl Aspects of the interAction wAs delineAted from circulAr dichroism studies wherein higher perturbAtion wAs observed with TBO. HydrodynAmic study using viscosity meAsurements of lineAr rod like DNA confirmed thAt the binding wAs intercAlAtive And strongest for TBO And weAker for Azure A And Azure B. The utility of the present work lies in exploring the potentiAl binding ApplicAbility of these dyes to DNA for their development As effective therApeutic Agents.
F Vicente - One of the best experts on this subject based on the ideXlab platform.
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evAluAtion of the electrochemicAl Anion recognition of no3 imprinted poly Azure A in no3 cl mixed solutions by Ac electrogrAvimetry
Electrochimica Acta, 2016Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, Hubert Perrot, Roger Sanchisgual, F VicenteAbstract:AbstrAct During the reversible electrochemicAl reActions of the intrinsicAlly conducting polymer (ICP) films, ions Are inserted in them to bAlAnce the inner chArge site of the polymer. For this reAson, doped ICP films with Anions or cAtions cAn be good cAndidAtes for the electrochemicAl removAl of contAminAnt ions from wAstewAter. In this work, A polymer of A phenothiAzine derivAtive (poly(Azure A or PAA)) wAs electrosynthesized by cyclic voltAmmetry in Aqueous solutions using nitrAte ions As A structurAl templAte. After thAt, PAA film wAs repeAtedly cycled in identicAl conditions in A monomer-free solution. The electrochemicAl Anion recognition of the nitrAte-imprinted poly(Azure A) ( N O 3 − − PAA ) wAs evAluAted by the combinAtion of electrochemicAl And mAss impedAnce spectroscopy, the so cAlled Ac-electrogrAvimetry method. Ac-electrogrAvimetry Allows the selectivity of N O 3 − − PAA to be quAntified. N O 3 − − PAA exhibited A speciAl sensitivity And selectivity for the nitrAte ions over the interfering chloride ions in mixed N O 3 − And Cl − contAining solutions. The Dixon plots of the kinetic constAnts obtAined by Ac-electrogrAvimetry were used As A grAphicAl method to reveAl thAt N O 3 − And Cl − trAnsfers Are non-competitive At lower doped stAtes of the polymer but competitive At higher doped stAtes. The reversibility of nitrAte incorporAtion controlled by An externAl potentiAl modulAtion, the relAtive low cost And eAsy synthesis render the N O 3 − − PAA film suitAble in prActicAl implicAtions such As nitrAte scAvenger in Aqueous contAminAted environments.
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ionic And free solvent motion in poly Azure A studied by Ac electrogrAvimetry
Journal of Physical Chemistry C, 2011Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, Hubert Perrot, F VicenteAbstract:This work is focused on the mechAnistic Aspects of the redox behAvior of poly(Azure A) tAking AdvAntAge of the controlled modulAtion of their oxidAtion stAtes by Ac-electrogrAvimetry. The originAlity of this technique is its Ability to discriminAte between cAtion And Anion involved in the chArge compensAtion process And the AccompAnying free solvent trAnsfer, directly or indirectly. Two processes were proposed where the fAster ionic exchAnge is considered to be the pArticipAtion of the Anion species Acting As counterions whereAs the slower one is relAted to the proton trAnsfer. The proton is implied As reActAnts for the two electroActive sites identified in the polymer chAin, the intermonomeric Amino links And the AromAtic rings. The Ac-electrogrAvimetry technique wAs used to study the kinetic Aspects of the trAnsfer of proton (H+), Anion (NO3– or Cl–), And free solvent in KNO3 And KCl Aqueous solutions.
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spectroelectrochemicAl identificAtion of the Active sites for protons And Anions insertions into poly Azure A thin polymer films
Journal of Physical Chemistry C, 2007Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, David Gimenezromero, H Perrot, F VicenteAbstract:Poly-(Azure A) films deposited on indium−tin oxide electrodes were simultAneously chArActerized by visible/neAr-infrAred spectroscopy And EIS techniques At different polArizAtion potentiAls And pH....
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vis nir spectroelectrochemicAl AnAlysis of poly Azure A on ito electrode
Electrochemistry Communications, 2006Co-Authors: Jeronimo Agrisuelas, J J Garciajareno, David Gimenezromero, F VicenteAbstract:Electrochromic behAvior of poly-(Azure A )o nindium–tin oxide electrode is AnAlyzed in An Aqueous potAssium nitrAte solution. The dependence of the AbsorbAnce on the Applied potentiAl during cyclic voltAmmogrAms proves very interesting At two selected chArActeristic wAvelengths: At 925 nm, Attributed to An intermediAte species And Another At 735 nm, Attributed to the oxidized form of the polymer. MolAr Absorptivity coefficients for both species hAve been cAlculAted from the relAtionship between current And the derivAtive of AbsorbAnce with respect to time. VoltAmmogrAms of formAtion of the intermediAte Are simulAted from spectroelectrochemicAl results. � 2006 Elsevier B.V. All rights reserved.
Jeronimo Agrisuelas - One of the best experts on this subject based on the ideXlab platform.
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A compArAtive study of poly Azure A film modified disposAble electrodes for electrocAtAlytic oxidAtion of h2o2 effect of doping Anion
Polymers, 2018Co-Authors: Jeronimo Agrisuelas, Mariaisabel Gonzalezsanchez, Beatriz Gomezmonedero, Edelmira ValeroAbstract:In the present pAper, poly(Azure A) (PAA) films were electrosynthetized in the presence of different doping Anions on disposAble screen-printed cArbon electrodes (SPCEs). The Anions used included inorgAnic monoAtomic (chloride And fluoride), inorgAnic polyAtomic (nitrAte And sulfAte) And orgAnic polyAtomic (dodecyl sulfAte, DS) species. The coAted electrodes thus obtAined were chArActerized by electrochemicAl techniques And SEM. They showed improved electrocAtAlytic Activities towArds hydrogen peroxide oxidAtion compAred to thAt of A bAre SPCE. In pArticulAr, the insertion of DS Anions inside PAA films provided A speciAl sensitivity to the electrocAtAlysis of H2O2, which endowed these electrodes with promising AnAlyticAl feAtures for H2O2 quAntificAtion. We obtAined A wide lineAr response for H2O2 within A rAnge of 5 µM to 3 mM And A limit of detection of 1.43 ± 0.10 µM (signAl-to-noise rAtio of 3). Furthermore, sensitivity wAs 72.4 ± 0.49 nA·µM−1∙cm−2 At A relAtively low electrocAtAlytic oxidAtion overpotentiAl of 0.5 V vs. Ag. The ApplicAbility of this boosted system wAs tested by the AnAlysis of H2O2 in commerciAl sAmples of A hAir lightener And An Antiseptic And wAs corroborAted by spectrophotometric methods.
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evAluAtion of the electrochemicAl Anion recognition of no3 imprinted poly Azure A in no3 cl mixed solutions by Ac electrogrAvimetry
Electrochimica Acta, 2016Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, Hubert Perrot, Roger Sanchisgual, F VicenteAbstract:AbstrAct During the reversible electrochemicAl reActions of the intrinsicAlly conducting polymer (ICP) films, ions Are inserted in them to bAlAnce the inner chArge site of the polymer. For this reAson, doped ICP films with Anions or cAtions cAn be good cAndidAtes for the electrochemicAl removAl of contAminAnt ions from wAstewAter. In this work, A polymer of A phenothiAzine derivAtive (poly(Azure A or PAA)) wAs electrosynthesized by cyclic voltAmmetry in Aqueous solutions using nitrAte ions As A structurAl templAte. After thAt, PAA film wAs repeAtedly cycled in identicAl conditions in A monomer-free solution. The electrochemicAl Anion recognition of the nitrAte-imprinted poly(Azure A) ( N O 3 − − PAA ) wAs evAluAted by the combinAtion of electrochemicAl And mAss impedAnce spectroscopy, the so cAlled Ac-electrogrAvimetry method. Ac-electrogrAvimetry Allows the selectivity of N O 3 − − PAA to be quAntified. N O 3 − − PAA exhibited A speciAl sensitivity And selectivity for the nitrAte ions over the interfering chloride ions in mixed N O 3 − And Cl − contAining solutions. The Dixon plots of the kinetic constAnts obtAined by Ac-electrogrAvimetry were used As A grAphicAl method to reveAl thAt N O 3 − And Cl − trAnsfers Are non-competitive At lower doped stAtes of the polymer but competitive At higher doped stAtes. The reversibility of nitrAte incorporAtion controlled by An externAl potentiAl modulAtion, the relAtive low cost And eAsy synthesis render the N O 3 − − PAA film suitAble in prActicAl implicAtions such As nitrAte scAvenger in Aqueous contAminAted environments.
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ionic And free solvent motion in poly Azure A studied by Ac electrogrAvimetry
Journal of Physical Chemistry C, 2011Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, Hubert Perrot, F VicenteAbstract:This work is focused on the mechAnistic Aspects of the redox behAvior of poly(Azure A) tAking AdvAntAge of the controlled modulAtion of their oxidAtion stAtes by Ac-electrogrAvimetry. The originAlity of this technique is its Ability to discriminAte between cAtion And Anion involved in the chArge compensAtion process And the AccompAnying free solvent trAnsfer, directly or indirectly. Two processes were proposed where the fAster ionic exchAnge is considered to be the pArticipAtion of the Anion species Acting As counterions whereAs the slower one is relAted to the proton trAnsfer. The proton is implied As reActAnts for the two electroActive sites identified in the polymer chAin, the intermonomeric Amino links And the AromAtic rings. The Ac-electrogrAvimetry technique wAs used to study the kinetic Aspects of the trAnsfer of proton (H+), Anion (NO3– or Cl–), And free solvent in KNO3 And KCl Aqueous solutions.
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spectroelectrochemicAl identificAtion of the Active sites for protons And Anions insertions into poly Azure A thin polymer films
Journal of Physical Chemistry C, 2007Co-Authors: Jeronimo Agrisuelas, C Gabrielli, J J Garciajareno, David Gimenezromero, H Perrot, F VicenteAbstract:Poly-(Azure A) films deposited on indium−tin oxide electrodes were simultAneously chArActerized by visible/neAr-infrAred spectroscopy And EIS techniques At different polArizAtion potentiAls And pH....
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vis nir spectroelectrochemicAl AnAlysis of poly Azure A on ito electrode
Electrochemistry Communications, 2006Co-Authors: Jeronimo Agrisuelas, J J Garciajareno, David Gimenezromero, F VicenteAbstract:Electrochromic behAvior of poly-(Azure A )o nindium–tin oxide electrode is AnAlyzed in An Aqueous potAssium nitrAte solution. The dependence of the AbsorbAnce on the Applied potentiAl during cyclic voltAmmogrAms proves very interesting At two selected chArActeristic wAvelengths: At 925 nm, Attributed to An intermediAte species And Another At 735 nm, Attributed to the oxidized form of the polymer. MolAr Absorptivity coefficients for both species hAve been cAlculAted from the relAtionship between current And the derivAtive of AbsorbAnce with respect to time. VoltAmmogrAms of formAtion of the intermediAte Are simulAted from spectroelectrochemicAl results. � 2006 Elsevier B.V. All rights reserved.
Edelmira Valero - One of the best experts on this subject based on the ideXlab platform.
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highly sensitive h2o2 sensor bAsed on poly Azure A plAtinum nAnopArticles deposited on ActivAted screen printed cArbon electrodes
Sensors and Actuators B-chemical, 2019Co-Authors: Rebeca Jimenezperez, Mariaisabel Gonzalezsanchez, Beatriz Gomezmonedero, Jose Gonzalezrodriguez, Edelmira ValeroAbstract:AbstrAct The sensitive determinAtion of hydrogen peroxide hAs broAd AnAlyticAl ApplicAtions. In this work, A novel non-enzymAtic hydrogen peroxide sensor bAsed on Pt nAnopArticles (PtNPs) electrochemicAlly deposited on previously modified And ActivAted screen-printed cArbon electrodes (ASPCEs) wAs constructed. The pretreAtment consisted of subjecting the electrodes to A surfAce ActivAtion treAtment with hydrogen peroxide followed by the electrodeposition of poly(Azure A) films (PAA) in A sodium dodecyl sulfAte micellAr Aqueous solution. The PtNPs/PAA/ASPCEs were chArActerized by scAnning electron microscope, X-RAy photoelectron spectrometry, lineAr scAn voltAmmetry And electrochemicAl impedAnce spectroscopy. LineAr sweep voltAmmogrAms showed thAt the oxidAtion peAk potentiAl of H2O2 shifts from ˜1 V At SPCEs to ˜0.1 V At PtNPs/PAA/ASPCEs. The fAbricAted electrodes showed excellent electrocAtAlytic Activity towArds H2O2 oxidAtion, mAking its detection possible At 0.1 V. The detection limit wAs 51.6 nM, which is significAntly lower thAn other modified electrodes found in the literAture, And the lineAr rAnge rAnging from 0 to 300 μM. The proposed electrode wAs successfully Applied to the determinAtion of H2O2 in reAl sAmples in different AreAs. AdditionAl experiments AgAinst common interfering Agents (Ascorbic Acid, dehydroAscorbic Acid, glucose, sAlicylic Acid, Among other compounds) showed no increAse in the current signAl And only in the cAse of Ascorbic Acid A smAll interference, not greAter thAn 10% is observed, which indicAtes high specificity of the sensor. These electrodes open up AlternAtive Avenues for the development of highly sensitive, robust And low cost electrochemicAl H2O2 sensors for field tests.
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A compArAtive study of poly Azure A film modified disposAble electrodes for electrocAtAlytic oxidAtion of h2o2 effect of doping Anion
Polymers, 2018Co-Authors: Jeronimo Agrisuelas, Mariaisabel Gonzalezsanchez, Beatriz Gomezmonedero, Edelmira ValeroAbstract:In the present pAper, poly(Azure A) (PAA) films were electrosynthetized in the presence of different doping Anions on disposAble screen-printed cArbon electrodes (SPCEs). The Anions used included inorgAnic monoAtomic (chloride And fluoride), inorgAnic polyAtomic (nitrAte And sulfAte) And orgAnic polyAtomic (dodecyl sulfAte, DS) species. The coAted electrodes thus obtAined were chArActerized by electrochemicAl techniques And SEM. They showed improved electrocAtAlytic Activities towArds hydrogen peroxide oxidAtion compAred to thAt of A bAre SPCE. In pArticulAr, the insertion of DS Anions inside PAA films provided A speciAl sensitivity to the electrocAtAlysis of H2O2, which endowed these electrodes with promising AnAlyticAl feAtures for H2O2 quAntificAtion. We obtAined A wide lineAr response for H2O2 within A rAnge of 5 µM to 3 mM And A limit of detection of 1.43 ± 0.10 µM (signAl-to-noise rAtio of 3). Furthermore, sensitivity wAs 72.4 ± 0.49 nA·µM−1∙cm−2 At A relAtively low electrocAtAlytic oxidAtion overpotentiAl of 0.5 V vs. Ag. The ApplicAbility of this boosted system wAs tested by the AnAlysis of H2O2 in commerciAl sAmples of A hAir lightener And An Antiseptic And wAs corroborAted by spectrophotometric methods.