1,720,981 research outputs found
Del canario al biosensor
No full textUn breve comentario sobre un proyecto en el cual estamos comenzando a trabajar y cuya motivación principal es lograr desarrollar biosensores basados en mecanismos de transducción fotoelectroquímica con aplicación concreta a la detección de marcadores de interés bioquímico.Fil: Benavidez, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Fast electrochromic response of ultraporous polyaniline nanofibers
Full text linkPolyaniline (PAni) nanofibers were prepared by a one-step electrosynthetic method. A gold sputtered electrode was used as the substrate for the nanofiber growth at a constant current density value of 100 μA cm-2. Substrate morphology induces fiber growing and allows having a remarkable quantity of fibers in a short period of time. Tandem chronoabsorptometric and chronocoulometric data of the electro-synthesis process were collected and analyzed. Several electrochromic parameters were characterized and a short response time (T90) of 20 ms was obtained for a contrast (ΔT %) of 10%. The main reason for this fast response is the ultraporous nature of the prepared nanofibers. This approach represents a straightforward, easy and low cost method to obtain a fast color switching film with potential application in the deployment of an electrochromic device.Fil: Erro, Eustaquio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Physicochemical properties of a mucin/chitosan matrix used for the development of an oxalate biosensor
No full textImmobilization conditions of biomolecules play an important role in a biosensor performance. In this paper the response of amperometric electrodes for oxalate is related with some physicochemical properties of the matrices where oxalate oxidase was immobilized. Swelling indexes, partition coefficients and permeability of oxalate in mucin/chitosan matrices in a pH = 2.85 succinic acid solution were measured. These properties were also determined in the 70/30 mucin/chitosan matrix in solutions containing succinic acid and sulfate or chloride anions at the same pH value. The results indicate that the sensitivity of the biosensors is mainly determined by the swelling index of the matrix. High slopes of the calibration curves of the electrodes were obtained with highly swollen matrices indicating the importance of a hydrophilic environment for a good enzymatic response.Fil: Benavidez, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones en Físicoquímica de Córdoba; Argentina; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Alvarez, Cecilia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones en Físicoquímica de Córdoba; Argentina; Argentina. Universidad Nacional de Córdoba; Argentin
Thermal annealing of photoanodes based on CdSe Qdots sensitized TiO2
Full text linkThermal annealing of photoanodes made of TiO2 nanotubes sensitized with CdSe quantum dots is studied. Heat treatment of these photoanodes in air can cause either an improvement or a serious drop in the photocurrent generation. Ligands or capping agents stabilize Qdots removing highly reactive dangling bonds on its surface but also they can act as a passivating layer that increases charge transfer resistance between Qdots and TiO2 nanotubes; therefore optimal conditions of thermal annealing are needed to improve efficiency of the interfacial charge transfer avoiding as far as possible the decomposition of the sensitizers. As a corollary of this study, a 2.5-fold increase in photocurrent value was reached after thermal annealing at 200 °C during at least two hours; while thermal treatments at temperature values higher than 250 °C can produce a deleterious effect on the conversion efficiency if the annealing time extends over a long period of time. Photoelectrochemistry, thermogravimetry and SEM microscopy were used as tools to propose a mechanism able to explain the observed behaviour.Fil: Torresan, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Analysis and optimization of a hydrogel matrix for the development of a sandwich-type glucose biosensor
No full textThe development of a sandwich-type biosensor for glucose quantification is presented. This work is focused on the optimization of the enzymatic matrix of the biosensor. The best performance was found for an enzymatic matrix composed by 30% w/w mucin, 70% w/w albumin, 1.35 U glucose oxidase (GOX) per sensor, and glutaraldehyde diluted to 3%. The crosslinking with glutaraldehyde transforms this mixture into a hydrogel that is entrapped between two membranes of polycarbonate. The selected sandwich-type biosensor showed very good response time, sensitivity, stability, and sensor-to-sensor reproducibility. According to the results presented in this manuscript, a biosensor prepared with very high amount of enzyme would not necessarily increase the analytical signal. Simulated curves are compared with experimental data to explain the dependence of sensitivity on the concentration of enzyme. In addition, this kind of comparison represents a quite simple way to estimate the value of vmax≈0.13 M s-1 from the amperometric response of a sensor prepared with 1.34 U of GOX. Considering that sandwich-type biosensors are commonly assembled as part of devices where the sample is diluted with buffer, the more than 3 orders of magnitude of linear behavior of this sensor would ensure the possibility for assessing any sample.Fil: Colombo, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Garay, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Catalytic EC reaction at a thin film modified electrode
No full textNumerical simulations of cyclic voltammograms corresponding to a catalytic EC reaction taking place at a thin film modified electrode are performed by way of finite difference method. Besides considering the chemical kinetic occurring inside the thin film, the model takes into account the different diffusion coefficients for each species at each of the involved phases, i.e. the thin film layer and bulk solution. The theoretical formulation is given in terms of dimensionless model parameters but a brief discussion of each of these parameters and their relationship to experimental variables is presented. Special emphasis is given to the use of working curve characteristics to quantify diffusion coefficient, homogeneous kinetic constant and thickness of the thin layer in a real system. Validation of the model is made by comparison of experimental results corresponding to the electron charge transfer of Ru(NH3)6 3+/Ru(NH3)6 2+ hemi-couple at a thin film of a cross-linked chitosan film containing an immobilized redox dye.Fil: Gerbino, Leandro Julian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Charge Extraction from TiO2 Nanotubes Sensitized with CdS Quantum Dots by SILAR Method
Full text linkQuantum dot (QD) solar cells based on different materials have received a noticeable interest during the past ten years; however, their efficiency and stability are still the main drawback of this technology, which leads to a lack of performance of these devices. There are several electron loss (and efficiency) processes involved after photon absorption, but perhaps the main issue is with the electron recombination after excitation of the surface. In this paper, we have studied the dependence of short-circuit photocurrent of TiO2 nanotubes with varying amounts of CdS QDs deposited by the successive ionic layer adsorption and reaction method. We have found that there is an optimum coverage of CdS in order to achieve the maximum photocurrent value. This behavior is explained and characterized in terms of prevailing recombination processes at higher CdS coverage, where quantum confinement becomes less important. By using the charge extraction method, we could determine the time dependence of electrode charge and indicates that the back reaction of electrons with the redox electrolyte present in solution is of the first order in electron density and that it originates from the electrons present in the TiO2 conduction band.Fil: Vazquez, Cecilia Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Iglesias, Rodrigo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Comparative behavior of glucose oxidase and oxalate oxidase immobilized in mucin/chitosan hydrogels for biosensors applications
Full text linkThe analytical response of amperometric glucose electrodes was explained in the framework of the properties of hydrogels with different muc/chit ratio at pH = 7.00 used as immobilization matrix for glucose oxidase. The continuous increase in the sensitivity of the electrodes with the amount of chitosan was attributed to a more efficient crosslinking without affecting the enzyme activity. The results were compared with those obtained using the same matrices to immobilize Oxalate Oxidase at pH = 2.85 where it has the highest activity. A maximum sensitivity at muc/chit 70/30 ratio for these oxalate electrodes was observed. Decrease in permeability of negatively charged oxalate with the chitosan content in the matrices, in spite of the high partition coefficient, explains the analytical differences with glucose electrodes. Swelling and viscoelasticity of the hydrogels allowed to asses the importance of a hydrophilic environment for the enzyme in both cases. © 2011 Elsevier Ltd. All rights reserved.Fil: Benavidez, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
Preparation, characterization and application of modified surfaces with 3,5-Bis (3,5-dinitrobenzoyl-amino) benzoic acid
Full text linkThe spontaneous adsorption of the dendron 3,5-Bis (3,5-dinitrobenzoylamino) benzoic acid (D-NO2) onto gold and carbon electrodes produced conductive surfaces with electroactive chemical functions. A comparative electrochemical behavior of both electrodes after dendron immobilization led us to conclude that the self-assembly of D-NO2 on carbon is faster and stronger. Considering this advantage, the surface of magnetic maghemite nanoparticles (MNPs) was modified using D-NO2. Firstly, MNPs were modified with APS as silane coupling agent and afterwards, D-NO2 was covalently attached to the surface, achieving nitro-functionalized MNPs. Subsequently, the immobilization of these modified MNPs onto glassy carbon surfaces was explored to generate a novel platform promising for biosensors development.Fil: Paez, Julieta Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Capelletti, Ariel L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones en Físicoquímica de Córdoba; Argentina; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Brunetti, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Investigaciones en Físicoquímica de Córdoba; Argentina; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina. Universidad Nacional de Córdoba; Argentin
How low does the oxygen concentration go within a sandwich-type amperometric biosensor?
No full textSoftware for the automatic non-linear least squares fit of chronoamperometric responses corresponding to sandwich-type amperometric biosensors has been developed. The so-called Simplex algorithm computes a minimum value for the difference between experimental and theoretical data. The latter consider a numerical model based on a ping-pong reaction mechanism corresponding to an oxidase enzyme that has been immobilized between diffusion membranes. The results obtained from the simulation of a first-generation lactate biosensor in presence of 0.1 mM substrate indicate that the concentration of O 2 would decrease only 0.1% with regards to its bulk value. Besides, the concentration of this natural mediator would remain practically unchanged during a typical calibration curve. This is because the rather high diffusion coefficient of O 2 and its regeneration at the electrode surface minimize the concentration changes of this species. In addition, it was found that the thicknesses of polycarbonate membranes and the enzymatic matrix have average values of 13 μm and 20 μm, respectively. However, these membranes might exhibit smaller thickness depending on the time provided for the crosslinking reaction. In this regard, if this reaction is slow enough, the enzymatic matrix would be able to diffuse through the pores of polycarbonate membranes and they will appear to be thinner than expected. This effect may compromise the response-time and the reproducibility of this kind of biosensors.Fil: Romero, Marcelo Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Baruzzi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Garay, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin
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