Materiales moleculares. Aplicaciones en narices y lenguas electrónicas

Presentaciones de la Decimotercera Jornada de Materiales de la Universidad Carlos III de Madrid celebrada el 31 de marzo de 2011 en Leganés, MadridNo publicad

Discrimination of milks with a multisensor system based on layer-by-layer films

Producción CientíficaA nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity, and chitosan (CHI), that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV–vis, and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal component analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using a PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components, such as fats, proteins, and acidity, can also be obtained. The method developed is simple, and the short response time permits its use in assaying milk samples online.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16)Junta de Castilla y León (grant BOCYL-D-4112015-9

Polymeric foams as the matrix of voltammetric sensors for the detection of catechol, hydroquinone, and their mixtures

Producción CientíficaPorous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16

Editorial: electrochemical sensors and biosensors in medical and pharmaceutical bioanalysis

Producción CientíficaThis Research Topic collects different contributions in the emerging field of bioanalysis, highlighting the most relevant advances reported in the literature as well as some original research studies in medical and pharmaceutical bioanalysis. The first article of this Topic (Antonacci et al.), describes in a detailed review state of the art the paper-based electrochemical devices for pharmaceutical field. In the last few decades, scientific research has been trying to offer valid and reliable solutions to replace or support conventional techniques, in order to facilitate drug development procedures. These innovative approaches may have extremely positive effects in the production chain, supplying fast and cost-effective quality and safety tests on active pharmaceutical ingredients and their excipients. In this context, the exploitation of electrochemical paper-based analytical devices is still in its infancy, but particularly promising for its fascinating properties in the detection of active pharmaceutical ingredients and excipients in tablets, capsules, suppositories, and injections, as well as for pharmacokinetic bioanalysis in real samples

Bioelectronic tongue based on lipidic nanostructured layers containing phenol oxidases and lutetium bisphthalocyanine for the analysis of grapes

Producción CientíficaIn this work, a multisensor system formed by nanostructured voltammetric biosensors based on phenol oxidases (tyrosinase and laccase) has been developed. The enzymes have been incorporated into a biomimetic environment provided by a Langmuir-Blodgett (LB) film of arachidic acid (AA). Lutetium bisphthalocyanine (LuPc2) has also been introduced in the films to act as electron mediator. The incorporation of the enzymes to the floating layers to form Tyr/AA/LuPc2 and Lac/AA/LuPc2 films has been confirmed by the expansion in the surface pressure isotherms and by the AFM images. The voltammetric response towards six phenolic compounds demonstrates the enhanced performance of the biosensors that resulted from a preserved activity of the tyrosinase and laccase combined with the electron transfer activity of LuPc2. Biosensors show improved detection limits in the range of 10-7-10-8molL-1. An array formed by three sensors AA/LuPc2, Tyr/AA/LuPc2 and Lac/AA/LuPc2 has been employed to discriminate phenolic antioxidants of interest in the food industry. The Principal Component Analysis scores plot has demonstrated that the multisensor system is able to discriminate phenols according to the number of phenolic groups attached to the structure. The system has also been able to discriminate grapes of different varieties according to their phenolic content. This good performance is due to the combination of four factors: the high functionality of the enzyme obtained using a biomimetic immobilization, the signal enhancement caused by the LuPc2 mediator, the improvement in the selectivity induced by the enzymes and the complementary activity of the enzymatic sensors demonstrated in the loading plots.Ministerio de Economía, Industria y Competitividad – FEDER (Grant CICYT AGL2012-33535)Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA-032U13

Characterization of porous nickel-free austenitic stainless steel prepared by mechanical alloying

Nickel-free austenitic powder metallurgy stainless steels were prepared and characterized. The main issue was to obtain potential biocompatible materials. Mechanical alloying in a nitrogen atmosphere was used to obtain these powders. The main factor to be controlled was the milling time. Powder metallurgy was the technique to obtain massive samples from alloyed powders. Two sintering processes were applied by controlling the sinter-cooling rate (furnace and water-cooling). The sintering atmosphere applied was nitrogen because of its gammagenic effect. Samples made of powders milled for 48 h, sintered in nitrogen and water-cooled showed a clean austenitic microstructure, which is a suitable microstructure for biological applications. A complete microstructural characterization, including optical metallography, image analysis, Scanning Electron Microscopy with X-ray microanalysis, X-Ray diffraction and Vickers hardness and microhardness, was carried out. The electrochemical behaviour in a simulated body fluid, phosphate buffered saline, was also studied. The biocorrosion behaviour was evaluated in terms of anodic polarization measurements.2020-07-102020-07-1

Analysis of musts and wines by means of a bio-electronic tongue based on tyrosinase and glucose oxidase using polypyrrole/gold nanoparticles as the electron mediator

Producción CientíficaA bioelectronic tongue (bioET) based on combinations of enzymes (tyrosinase and glucose oxidase) and polypyrrole (Ppy) or polypyrrole/AuNP (Ppy/AuNP) composites was build up and applied to the analysis and discrimination of musts and wines. Voltammetric responses of the array of sensors demonstrated the effectiveness of polymers as electron mediators and the existence of favorable synergistic effects between Ppy and the AuNPs. Using Principal Component Analysis and Parallel Factor Analysis it was possible to discriminate musts according to the °Brix and TPI (Total Polyphenol Index), and wines according to the alcoholic degree and TPI. Partial Least Squares provided good correlations between the bioET output and traditional chemical parameters. Moreover, Support Vector Machines permitted to predict the TPI and the alcoholic degree of wines, from data provided by the bioET in the corresponding grapes. This result opens the possibility to predict wine characteristics from the beginning of the vinification process.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R)Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA275P18)Junta de Castilla y León (grant BOCYL-D-4112015-9

Promoting laccase sensing activity for catechol detection using LBL assemblies of chitosan/ionic liquid/phthalocyanine as immobilization surfaces

Producción CientíficaThe performance of electrochemical laccase-based biosensors can be improved by immobilizing the enzyme on composite Layer-by-Layer (LbL) supports in which materials with complementary functions are combined. LbL films are formed by layers combining an electrocatalytic material which favors electron transfer (sulfonated copper phthalocyanine, CuPcS(−)), an ionic liquid which enhances the electrical conductivity of the layers (1-butyl-3-methylimidazolium tetrafluoroborate, IL(+)) and a material able to promote enzyme immobilization (chitosan, CHI(+)). Composite films with different structures have been demonstrated to be efficient electrocatalysts, producing an increase in the magnitude of the responses towards catechol. The most intense and reproducible electrocatalytic effect was observed when a layer of the CuPcS(−) was placed on top of a layer formed by a mixture of CHI(+) + IL(+) to obtain [CHI(+) + IL(+)|CuPcS(−)]2 films. Biosensors with laccase immobilized on the surface of the LbL layers [CHI(+) + IL(+)|CuPcS(−)]2|Lac showed mediated electron transfer between the redox enzyme and the film and a reproducibility of device-to-device performance of 4.1%. The amperometric biosensor showed a sensitivity of 0.237 A·M−1 and a linear detection range from 2.4 μM to 26 μM for catechol. The excellent Limit of detection (LOD) of 8.96·10−10 M (3·σ /m) is one order of magnitude lower than that obtained in similar studies. A Michaelis-Menten constant of 3.16 μM confirms excellent enzyme-substrate affinity.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (projects AGL2015-67482-R and RTI2018_097990-B-100)Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA275P18