0000000000009834
AUTHOR
David Giménez-romero
Label-free piezoelectric biosensor for prognosis and diagnosis of Systemic Lupus Erythematosus
[EN] An autoantigen piezoelectric sensor to quantify specific circulating autoantibodies in human serum is developed. The sensor consisted on a quartz crystal microbalance with dissipation monitoring (QCM-D) where TRIM21 and TROVE2 autoantigens were covalently immobilized, allowing the selective determination of autoantibodies for diagnosis and prognosis of Systemic Lupus Erythematosus (SLE). The sensitivity of the biosensor, measured as IC50 value, was 1.51 U/mL and 0.32 U/mL, for anti-TRIM21 and anti-TROVE2 circulating autoantibodies, respectively. The sensor is also able to establish a structural interaction fingerprint pattern or profile of circulating autoantibodies, what allows scorin…
Elucidation of Carbohydrate Molecular Interaction Mechanism of Recombinant and Native ArtinM
[EN] The quartz crystal microbalance (QCM) technique has been applied for monitoring the biorecognition of ArtinM lectins at low horseradish peroxidase glycoprotein (HRP) concentrations, using a simple kinetic model based on Langmuir isotherm in previous work.(18) The latter approach was consistent with the data at dilute conditions but it fails to explain the small differences existing in the jArtinM and rArtinM due to ligand binding concentration limit. Here we extend this analysis to differentiate sugar-binding event of recombinant (rArtinM) and native (jArtinM) ArtinM lectins beyond dilute conditions. Equivalently, functionalized quartz crystal microbalance with dissipation monitoring (…
An approach to the electrochemical activity of poly-(phenothiazines) by complementary electrochemical impedance spectroscopy and Vis–NIR spectroscopy
Abstract The electroactivity of two poly-(phenothiazine), the poly-(Azure A) and the poly-(Methylene Blue), has been compared in this work. The spectroelectrochemical results prove clearly the existence of two electroactive moieties integrated in the polymeric lattice, the phenothiazine ring (detected by changes of absorbance at 590 and 685 nm) and the newly formed covalent links which fixes the monomers in the backbone of the polymer (detected by changes of absorbance at 460 and 875 nm). Differences in the electrochemical response of both polymers are due to differences in this covalent link. However in both polymers, the charge balance during electrochemical reactions takes place by the e…
Electrochemical impedance spectroscopy as a tool to estimate thickness in PB films
The analysis of the faradaic impedance of electroactive films provides a characteristic point from which it is possible to estimate the thickness of thin films. Thus, electrochemical impedance spectroscopy was used in this paper as a fast and easy technique to estimate this thickness. The proposed method was checked on PB films. Keywords: Prussian blue, Electrochemical impedance spectroscopy, Thickness
Electronic Perspective on the Electrochemistry of Prussian Blue Films
The derivative of the voltabsommetric scans, together with previous nano-electrogravimetric and X-ray diffraction results, allow different electrochemical processes to be distinguished during the Prussian blue (PB) voltammetric scan. Potassium, proton, and hydrated proton counterions involved in PB electrochemistry are related here to the electrochemical reactions of specific Fe sites. Potassium counterions show two different sites for their insertion: one located in the crystalline framework and another in ferrocyanide vacancies. From the monitoring of electroactive Fe sites, the covalent-exchange model is suggested as one of the first approaches to explain the origin of the PB magnetic or…
Innovative Combination of Three Alternating Current Relaxation Techniques: Electrical Charge, Mass, and Color Impedance Spectroscopy. Part I: The Tool
Technical details concerning the simultaneous acquisition of three impedance functions (electrochemical impedance spectroscopy, alternating current electrogravimetry or mass impedance, and alternating current colorimetry or color impedance) are presented. The analysis of each type of impedance function gives interesting information about the species participating during the electrochemical processes. Furthermore, obtaining three impedance functions in situ allows the crossed impedance functions to be calculated. These functions are especially useful in detecting delays between the color, mass, and electrical charge response of the system to the same perturbation, and it allows species parti…
An Electronic Perspective On The Electrochemical Changeover In Prussian Blue-Like Materials
Derivative voltabsometric scans together with previous electrogravimetric results allow to distinguish between the different electrochemical processes due to Fe-sites located into the Prussian Blue crystalline framework and other located next to ferrocyanide vacancies. The potassium, proton and hydrated proton counterions involved in these reactions are correlated to changes in near-UV/VIS/near-IR spectra. Potassium counter-ions show two different sites for insertion: one located into the crystalline framework and the other into ferrocyanide vacancies. From the monitoring of electroactive Fe-sites, it is possible to assume that the reduction of all Fe-sites located next to ferrocyanide vaca…
Mass/charge balance as a tool to estimate dimensional change in polypyrrole-based actuators
The deconvolution of the voltammograms of polypyrrole electrochemistry has proved to be possible through the electrochemical quartz crystal microbalance data using the F(dm/dQ) function. This deconvolution allows the evolution of the thickness of the polypyrrole films during their redox processes to be estimated and therefore, the mechanical contraction/decontraction of this polymer as a function of the ionic exchange processes can be evaluated. Keywords: Polypyrrole, EQCM, Thickness change
Usefulness of F(dm/dQ) Function for Elucidating the Ions Role in PB Films
The conversion process of "insoluble" prussian blue (PB) films into the "soluble" structure has been followed by the simultaneous measurement of current and mass changes during voltammetric experiments and focusing on the possibilities of the use of the instantaneous mass/electrical charge ratio at each potential. A similar procedure was used for the analysis of the mechanism of reduction of PB films to the Everitt's salt form and to follow the partial dissolution of iron species during the oxidation to the prussian yellow form. The possibility of covering PB films by Nafion membranes, which make difficult the transport of anions through it, allows us to discern the role of anions in the so…
Correlationship between microscopic observations and electrochemical behaviour of different kind of galvanized steel.
Zinc anodic dissolution has been studied according to the steel galvanized method by means of the electrochemical impedance spectroscopy (EIS) and microscopic observations. Relevant information on the galvanized method is provided by the analysis of experimental data. The galvanized method has no influence on the kinetics parameters of the zinc anodic dissolution process. The galvanized method only changes the surface texture of the working electrode. Thus, the EIS fitting allows to calculate the fractal dimension of the surface of the working electrode.
Electrochemical capacitance spectroscopy and capacitive relaxation of the changeover process in iron hexacyanoferrate molecular compound
Abstract In this work it was proposed the use electrochemical capacitance spectroscopy (ECS) to evaluate the storage process during changeover in FeHCF compound. The approach is equivalent to electrochemical impedance spectroscopy (EIS) albeit from such analysis it was possible to focus attention on the capacitive and dielectric relaxation instead of the dispersive relaxation related to charge transfer. From such approach it was possible to obtain complementary information on the role played by [Fe 2+ (CN) 6 ] 4− vacancies during the changeover process. It was observed that Fe 3+ (NC) 5 OH − clusters located in these vacancies mediate an electronic and ionic coupled trapping/detrapping proc…
Correlation between the fractal dimension of the electrode surface and the EIS of the zinc anodic dissolution for different kinds of galvanized steel
The roughness of the working electrode is one of the factors that affects the electrochemical impedance spectroscopy (EIS) data of the zinc anodic dissolution process. The fractal dimension of digital images of shooping plate, hot dip galvanized steel, continuous hot-dipped galvanized steel and electro-galvanized steel are related with their respective EIS data. Keywords: EIS, Fractal dimension, Roughness, Galvanized steel, Corrosion
Kinetics of zinc anodic dissolution from the EIS characteristic points
A possible faradaic impedance function for the complex mechanism of metals electrodissolution across two consecutive electrotransferences has been developed in this work. The analysis of this function provides some characteristics points from which it is possible to calculate kinetic parameters of these processes. The dependence of these parameters on the potential has been studied in the case of Zn. These ones have been interpreted in terms of changes in the controlling stages of the overall rate of reaction. Keywords: EIS simulation, Zinc anodic dissolution, Kinetic constants and electron transfer
Growth of passive layers on nickel during their voltammetric anodic dissolution in a weakly acid medium
Abstract Quartz crystal microbalance in combination with voltammetry has been used for studying the electrochemical oxidation behaviour of a nickel deposit in a weakly acid medium. The instantaneous mass/charge ratio (Fdm/dQ) analysis allows to obtain the fraction of charge consumed in the passivation process, and, that way, the experimental kinetic equation of the passive layer growth. This experimental law has been fitted to the theoretical equation derived from the point defect model theory under voltammetric conditions.
Effect of Anions and Oxygen on the Kinetics of the Anodic Dissolution of Nickel
An electrochemical impedance spectroscopy study on electrochemical dissolution and active/passive transition of polycrystalline nickel in acid media has been performed in sulfate and nitrate aqueous solutions. Oxygen favors the nickel electrodissolution in a nitrate aqueous acid medium, but the dissolution decreases in the sulfate medium due to nickel passivation. The anion and oxygen effect is analyzed from a model where Ni(I) species are stabilized on the Ni metal surface and all anions present in the solution compete in the neutralization of Ni(I) and Ni(II) and in the solubilization of Ni(II).
Quartz Crystal Microbalance And Electrical Impedance Characterization Of Nickel Dissolution Process.
Abstract. The anodic nickel dissolution in acid media is analysed by means of EQCM and EIS techniques. The experimental impedance spectra have been fitted to the equivalent circuit which corresponds to two consecutive electron transfers followed by a Ni(II) desorption. That way rate constants and surface concentrations of the Ni(0) and Ni(I) species are obtained. EQCM also provides information about the mechanism of deposition and passivation of nickel as well as the hydrogen evolution.
Dual-Polarization Interferometry: A Novel Technique To Light up the Nanomolecular World
[EN] The challenging lecture given in 1959 by physicist and Nobel Prize awarded R. P. Feynman: “There's plenty of room at the bottom” is considered to be the starting point for nanotechnology. With this peculiar title, Feynman encouraged researchers to explore beyond the atomic level and predicted exciting new phenomena that might revolutionize science and technology. Among these pioneering researchers are Eric Betzig, Stefan W. Hell and William E. Moerner, who have been awarded with the Nobel Prize in Chemistry 2014 for developing the super-resolved fluorescence microscopy. However, it is important to remark that the exploration of this amazing nanomolecular world began in the early 1980s …
EIS and Ac-electrogravimetry study of PB films in KCl, NaCl, and CsCl aqueous solutions
Prussian Blue films have been studied by means of ac-electrogravimetry, electrochemical impedance spectroscopy, and electrochemical quartz crystal microbalance in different aqueous salt solutions. Impedance data was interpreted in terms of a model based on a potential drop at the electrode/film interface and a potential drop at the film/solution interface. Quantitative results obtained by the fitting of impedance and ac-electrogravimetry allow to conclude that the main contribution to the potential drop at the film/solution interface is due to the dehydration-hydration process of cations on entering or leaving the film.
Vis/NIR spectroelectrochemical analysis of poly-(Azure A) on ITO electrode
Electrochromic behavior of poly-(Azure A) on indium–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. Keywords: Poly-(Azure A), Spectroelect…
Evidence of Magnetoresistance in the Prussian Blue Lattice during a Voltammetric Scan
This manuscript reports evidence of magnetoresistance effects in the Prussian Blue lattice during a voltammetric scan at room temperature. Accordingly, the PB is a well-known semiconductor that becomes surprisingly an almost metallic conductor in the presence of an internal magnetic field induced during the voltammetric scan. This offers appealing perspectives for the control of this interesting phenomenon from electrochemical techniques that could be used for the fabrication of the recent phase-change computational memories, which are electronically configurable. Herein, the PB magnetic properties have been monitored in situ by means of resonating magnetic microsensors based on the shift i…
Modeling of the role of conformational dynamics in kinetics of the antigen-antibody interaction in heterogeneous phase.
[EN] A novel approach that may potentially be used to study biomolecular interactions including the simultaneous determination of structural and kinetic binding parameters is described in this Article for the first time. It allows a rigid distinction between the possible reaction mechanisms of biomolecular recognition, induced fit and conformational selection. The relative importance of the two pathways is determined not by comparing rate constants but the structural aspects of the interaction instead. So the exact location of antigen molecules with respect to the capture antibody is depicted experimentally, avoiding the use of X-ray crystallography. The proposed pattern is applied to study…
An electromechanical perspective on the metal/solution interfacial region during the metallic zinc electrodeposition
The difficulty of studying the metal/solution interfacial region makes the use of non-conventional measurement techniques indispensable. In this way, a careful in situ study by means of acoustic impedance techniques coupled with nano-electrogravimetric techniques allowed this interface to be monitored during the metallic zinc electrodeposition process. This paper proves the formation of a viscoelastic layer consisting of ultra-hydrated Zn(II)/Zn(I) salts as a key step in the metallic zinc electrodeposition mechanism in sulfate aqueous solutions. Surprisingly, this layer is located in the metal/solution interfacial region and not on the reaction substrate. The chloride ions effect on the met…
Comments on the paper entitled ‘The formulation and modelling of the anodic dissolution of zinc through adsorbed intermediates’by G.G. Láng, and G. Horányi [J. Electroanal. Chem. 583 (2005) 148–154]
The points raised in the paper entitled "Comments on the paper entitled 'The formulation and modelling of the anodic dissolution of zinc through adsorbed intermediates"' have been discussed. It has been shown that, in contrast to the statements in the "Comments", most of the papers concerning the reaction schemes suggested for the interpretation of the dissolution or deposition of metals, which were considered as a support for the opinion of the Authors of the "Comments", support the views expressed in our original paper [J. Electroanal. Chem. 583 (2005) 148]. On the other hand, it has been stressed again that the criticism expressed in the original paper refers to dubious conclusions drawn…
Insights on the Mechanism of Insoluble-to-Soluble Prussian Blue Transformation
The electrochemical transformation of the soluble form of Prussian blue (PB) material from the insoluble form was monitored using electrochemical, gravimetric, acoustic, and spectroscopic techniques simultaneously. The described combination of in situ techniques represents an innovative tool for measurement in electrochemistry, which provides complementary information on the electrochemical systems. The insoluble-to-soluble PB transformation process takes place during the successive voltammetric cycles between the mixed valence form (PB) and the fully reduced form [Everitt's salt (ES)]. One of the processes that takes place is the exit of free Fe(CN) 4- 6 ions occluded in the vacancies of t…
Anodic Dissolution of Nickel across Two Consecutive Electron Transfers
The analysis of the electrochemical quartz crystal microbalance and electrochemical impedance spectroscopy results are consistent with a nickel electrodissolution process limited by the passage of Ni(I) to Ni(II), when chloride ions are present in the acid sulfate medium, or by the passage of Ni(II) to Ni 2+ in solution, in absence of chloride. This interpretation allows an explanation of the potential evolution of Fdm/dQ values in both experimental conditions by assuming the formation of a new phase on the electrode surface with a gel-like structure placed between the metal and the solution. Ni(I) surface concentration is calculated from the instantaneous mass/charge Fdm/dQ values.
Graphical Analysis of Electrochemical Impedance Spectroscopy of Two Consecutive Irreversible Electron Transfers. 1. Theoretical Study of the Anodic Dissolution of Metals
A general function for the faradaic impedance associated to a two consecutive single electron transfer mechanism followed by a irreversible first-order step has been obtained on the basis of formal kinetics. Kinetic parameters associated to this reaction mechanism can be obtained from the different kind of plots of the impedance function: Nyquist, Cole-Cole, and different Bode plots. A strategy for obtaining all parameters is suggested and analyzed on a detailed flowchart.
About the Insoluble to the Soluble Prussian Blue Transformation
Figure 1 shows firstly an increase of the motional resistance during the first scan of the transformation process, denoting an increase of the viscoelasticity of this structure. Soluble Prussian Blue have a localized changeover in the properties of these films just when Fe(III) fraction reaches the characteristic value. Secondly, this Figure shows an increase of motional resistance in zone 2 of the voltammetric scan, proving more evident for the last cycles than for the first ones. The increase of the motional resistance in zone 2 records an increase of the PB coercive field which at the same time, is due to an interesting changeover in the PB physiochemical properties localized at this pot…
Calculation of the surface concentration of Zn(I) from the anodic voltammetric peak of zinc combined with the QCM results
Deconvolution of voltammograms of anodic dissolution of zinc has proved to be possible through the electrochemical quartz crystal microbalance data and the F(dm/dQ) function. This deconvolution allows to calculate the surface concentration of Zn(I) and to obtain an estimation for the kinetic constant of the second single-electron transfer. Keywords: Zinc anodic dissolution, EQCM, Surface concentration, Deconvolution and kinetic constant
Analysis of an impedance function of zinc anodic dissolution
Zinc anodic dissolution has been studied by means of electrochemical impedance spectroscopy (EIS). The kinetic study of the oxidation mechanism has allowed us to propose a theoretical impedance function for this system in deaerated sulphate medium. Relevant information on the faradaic process is provided by analysis of the theoretical impedance function. Kinetic parameters of this system can be calculated from the fitting of experimental data to the faradaic impedance function deduced theoretically. The physical measurements of this function are analysed by means of the dependence of simulated EIS spectra on kinetic parameters.
Graphical analysis of electrochemical impedance spectroscopy of two consecutive irreversible electron transfers. 2. Zinc anodic dissolution in acid media.
The graphical analysis of the impedance plots is used in the study of the electrodic systems that take place through two consecutive single electron transfers. The zinc anodic dissolution is studied by using this procedure. The characteristic points easily allow us to explain and to simulate the impedance behavior of this electrodic system according to the steady-state potential and the roughness of the working electrode. The direct procedure for parametrical identification from the graphical analysis allows us to reduce the time needed for an impedance experiment. This graphical analysis is suggested for studying thin coated galvanized steels.
Singular points of electrochemical impedance function
A model of EIS response for a system with two consecutive monoelectron transfers is developed in this work. Relevant information on the mechanism of these electrochemical systems is provided by the parametrical identification of the theoretical faradaic impedance function. The kinetic parameters of this model are easily calculated through the calculus of the characteristic points of this function. This calculus allows to interpret the metals anodic dissolution according to the reaction mechanism and, therefore, allows us to establish easily the kinetic and thermodynamic behaviour of these systems with respect to any experimental parameter.
Innovative Combination of Three Alternating Current Relaxation Techniques: Electrical Charge, Mass, and Color Impedance Spectroscopy. Part II: Prussian Blue ⇆ Everitt’s Salt Process
The simultaneous recording of three impedance functions (electrochemical impedance, color, and mass impedance) allows the role of different species to be distinguished easily during electrochemical processes in conducting and electrochromic films. Herein, this technique has been applied to the study of the Prussian blue films at several potentials between the blue form (Prussian blue) and the colorless form (Everitt’s salt). At these potentials, these electrochemical reactions take place by means of exchange of different ions. Thus, the exchange of potassium cations is related to the changes of absorbance at 690 nm, whereas the exchange of protons does not introduce color changes at this wa…
Usefulness of the Instantaneous Mass-charge Ratio for Elucidating the Ions Role in the Stabilization and Dissolution Processes in Prussian Blue Films
The conversion process of 'insoluble' Prussian Blue films into the 'soluble' structure has been followed by the simultaneous measurement of current and mass changes during voltammetric experiments and focusing on the possibilities of the use of the instantaneous mass/electrical charge ratio at each potential. A similar procedure was used for the analysis of the mechanism of reduction of Prussian Blue films to the Everitt's Salt form and to follow the partial dissolution of iron species during the oxidation to the Pussian Yellow form. The possibility of covering Prussian Blue films by Nafion membranes which make difficult the transport of anions through it allows to discern the role of anion…
Simultaneous Anodic Dissolution and Passivation of Nickel in Moderate Acid Medium
The EQCM results show that nickel electrodissolution and nickel passivation occur simultaneously in a sulphate acid media of pH = 3.5. Mass balances have been done from the instantaneous F(dm/dQ) function. The fitting of the experimental i = f(E) and -dm/dt = g(E) curves to the theoretical equations allow to obtain information about the kinetic parameters and the molecular mass of the species involved in the electrochemical processes.
Enzyme Inhibition Microassays on Blu-Ray Disks for Drug Discovery
[EN] An enzyme inhibition-based assay for drug discovery developed by microarraing on Blu-ray disks is presented. As a proof-of-concept, the system screens a selected molecule library of potential chemical inhibitors against the glycoenzyme peroxidase, identifying the promising lead compounds with high selectivity using standard Blu-ray disks and drives. In order to face the first drug discovery stages, we establish the bases for a high-throughput screening assay and a methodology based on hypersurfaces suitable to manage a high number of data as well.
Electrochemical Quartz Crystal Microbalance Study of Copper Electrochemical Reaction in Acid Medium Containing Chlorides
Copper electrodissolution and electrodeposition were studied by means of gravimetric quartz crystal microbalance and electric cyclic voltammetry combined measurements. Relevant information on the mechanism of these electrochemical processes is provided by the analysis of experimental data and particularly of the mass change per charge unit. The copper electrodeposition and electrodissolution take place by means of two consecutive monoelectronic transfers where the anion participation in the reaction mechanism is specified. Besides, it is proved that the presence of molecular oxygen in the solution contributes to the formation of a passive layer on the surface of the metallic copper deposit.
Mapping molecular binding by means of conformational dynamics measurements
[EN] Protein-protein interactions are key in virtually all biological processes. The study of these interactions and the interfaces that mediate them play a key role in the understanding of biological function. In particular, the observation of protein¿protein interactions in their dynamic environment is technically difficult. Here two surface analysis techniques, dual polarization interferometry and quartz crystal microbalance with dissipation monitoring, were paired for real-time mapping of the conformational dynamics of protein¿ protein interactions. Our approach monitors this dynamics in real time and in situ, which is a great advancement within technological platforms for drug discover…
EQCM and EIS studies of Znaq2++2e−⇄Zn0 electrochemical reaction in moderated acid medium
The zinc electrodissolution and electrodeposition have been studied by means of electrochemical quartz crystal microbalance and electrochemical impedance spectroscopy. Relevant information on the mechanism of these electrochemical processes is provided by the analysis of experimental data. The zinc electrodeposition takes place with an important participation of hydrogen ions while the zinc electrodissolution occurs, in these experimental conditions, by a mechanism in two steps. Besides, it is proved that the presence of molecular oxygen in the solution contributes to the formation of a passive layer on the metallic zinc deposit.
Evidence for Conformational Mechanism on the Binding of TgMIC4 with β-Galactose-Containing Carbohydrate Ligand
A deeper understanding of the role of sialic/desialylated groups during TgMIC4-glycoproteins interactions has importance to better clarify the odd process of host cell invasion by members of the apicomplexan phylum. Within this context, we evaluated the interaction established by recombinant TgMIC4 (the whole molecule) with sialylated (bovine fetuin) and desialylated (asialofetuin) glycoproteins by using functionalized quartz crystal microbalance with dissipation monitoring (QCM-D). A suitable receptive surface containing recombinant TgMIC4 for monitoring β-galactose-containing carbohydrate ligand (limit of quantification ∼ 40 μM) was designed and used as biomolecular recognition platform t…
Identification of high-affinity phage-displayed VH fragments by use of a quartz crystal microbalance with dissipation monitoring
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