Electronic tongue technology applied to the analysis of grapes and wines

El desarrollo de nuevos métodos de análisis para caracterizar los alimentos es de vital importancia para mejorar los actuales sistemas de control de calidad de los productos alimenticios. Dentro de este campo, el concepto de lengua electrónica (ETs o e-tongues) ha crecido rápidamente en los últimos años debido a su gran potencial. Estos dispositivos se basan en sensores electroquímicos combinados con análisis de datos multivariantes. De acuerdo con la IUPAC (Unión Internacional de Química Pura y Aplicada), una lengua electrónica es un sistema multisensor, que consiste en un número de sensores de baja selectividad y utiliza procedimientos matemáticos avanzados para el procesamiento de señales basados en el reconocimiento de patrones (PARC) y/o análisis multivariante [redes neuronales artificiales (RNA), análisis de componentes principales (PCA), etc.]. Por lo tanto, las ETs son sistemas holísticos que proporcionan información global y cualitativa acerca de la muestra en lugar de datos cuantitativos acerca de compuestos específicos. Sin embargo, si la matriz de datos obtenida por estos sistemas se analiza con herramientas de procesamiento quimiométrico adecuadas, se podría extraer información descriptiva o predictiva de parámetros específicos. Existe un término más reciente en el campo de las lenguas electrónicas, ampliamente denominado lengua bioelectrónica (bioET), que incluye el uso de uno o varios biosensores implementados en las ETs. Durante esta investigación se han aplicado ETs y bioETs para estudiar las uvas tintas y los vinos con el fin de predecir mejor el momento óptimo de la vendimia de uvas, así como los parámetros de calidad de interés en los vinos.Departamento de Química Física y Química InorgánicaDoctorado en Físic

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

Las posiciones maternas durante el parto: una visión diferente desde la enfermería

Trabajo fin de grado en EnfermeríaObjetivo: Analizar y comparar los beneficios e inconvenientes que tienen las diferentes posiciones que las mujeres pueden adoptar durante la primera y segunda etapa del trabajo de parto, además de explorar la influencia de los profesionales en su adopción y las consecuencias de su actuación. Metodología: Se llevó a cabo una búsqueda bibliográfica en las bases de datos: PubMed, Cinahl, Cochrane, Cuiden, Encuentra y el repositorio Dialnet. Se limitó a documentos publicados en los últimos diez años en idioma inglés y español. Se utilizó lenguaje libre y controlado (MesH y palabras clave) combinando los términos de búsqueda empleados a través del operador booleano «AND». Resultados: Se seleccionaron 24 documentos que se encuadraron en 5 unidades de análisis: beneficios y posibles complicaciones de las posiciones verticales y horizontales, influencia de las posiciones en la percepción del dolor, influencia de los profesionales en la adopción de las diferentes posiciones y posibles consecuencias de su actuación e influencia de las posiciones en la experiencia de parto en madres y padres, al ser los aspectos considerados más relevantes tras el análisis de los documentos incluidos. Conclusiones: Múltiples estudios muestran los beneficios de adoptar posiciones verticales en lugar de horizontales durante el parto, siendo las primeras muy relevantes en la percepción de dolor materno y para facilitar el parto. También influyen positivamente en la experiencia de parto en padres y madres, así como la actuación de los profesionales sanitarios, que adecuadamente formados generen sentimiento de control, fomenten la participación activa y la toma de decisiones.Aim: Analyze and compare the advantages and disadvantages about different positions which womans can adopt during the first and second stage of childbirth, as well as, explore the professionals influence in their adoption and the consequences of their interventions. Methodology: A review was realized by the databases: PubMed, Cinahl, Cochrane, Cuiden, Encuentra and Dialnet repository. Documents were limited to the last 10 years and English and Spanish language. We used controlled and free language (MeSH and keywords) combining the terms through the boolean operator «AND». Results: 24 papers were selected, estabilishing as units of analysis: benefits and possible complications of vertical and horizontal positions, influence of positions on pain perception, influence of professionals in the adoption of different positions and possible consequences of their interventions and influence of positions in the childbirth experience in mothers and fathers, being considered the most relevant aspects after the paper analysis. Conclusions: Multiple studies show the benefits of adopting vertical positions rather than horizontal positions during childbirth, which are very relevant in mother’s pain perception. They also have a positive influence in childbirth experience in mothers and fathers, as well as the health professionals actuation, which adequately trained, can generate a sense of control, encourage active participation and decision makin

Desarrollo de una lengua electrónica para el análisis de uvas basada en sensores EQCM modificados

Se ha desarrollado una lengua electrónica formada por sensores basados en microbalanza de cristal de cuarzo (QCM) modificados con ftalocianinas para estudiar los procesos asociados con las variaciones de masa que acompañan la oxidación/reducción de especies electroactivas presentes en los mostos. Para ello, se han depositado películas delgadas nanoestructuradas de ftalocianina sulfónicas de cobre, nickel y hierro sobre electrodos de platino/cristal de cuarzo mediante la técnica de Layer by Layer. El crecimiento de las películas se monitorizó con espectroscopia UV-visible. Se estudió la variación de masa observando la variación de frecuencia del cristal de acuerdo con la Ecuación de Sauerbrey. Una vez preparados los sensores, se han analizado mostos de variedades diferentes de uva (Juan García, Prieto Picudo, Mencía Regadío, Cabernet Sauvignon, Garnacha and Tempranillo) proporcionadas por la Estación Enológica de Castilla y León (Rueda, Valladolid), por el Instituto Tecnológico Agrario de Castilla y Léon (Valladolid) y la Bodega Cooperativa de Cigales (Cigales, Valladolid). Los sensores electroquímicos de cristal de cuarzo (EQCM) aportaron información de la composición global de las muestras de uva ofreciendo, simultáneamente, información voltamétrica y másica. Los datos de la QCM y voltamétricos fueron procesados para evaluar la capacidad de la lengua electrónica para discriminar diferentes variedades de uva. Se llevaron a cabo análisis estadísticos utilizando el modelo no supervisado de PCA (análisis de componentes principales) para discriminar las muestras de mosto y PLS (regresión de mínimos cuadrados parciales) evidenció las correlaciones entre los datos voltamétricos y másicos con los indicadores químicos. Este trabajo de investigación supone la primera vez que una lengua electrónica basada en sensores EQCM ha sido utilizada para discriminar variedades de uva de acuerdo a su composición global, utilizando para ello la respuesta voltamétrica y másica.Departamento de Química Física y Química InorgánicaMáster en Nanociencia y Nanotecnología Molecula

Biosensors Platform Based on Chitosan/AuNPs/Phthalocyanine Composite Films for the Electrochemical Detection of Catechol. The Role of the Surface Structure

Producción CientíficaBiosensor platforms consisting of layer by layer films combining materials with different functionalities have been developed and used to obtain improved catechol biosensors. Tyrosinase (Tyr) or laccase (Lac) were deposited onto LbL films formed by layers of a cationic linker (chitosan, CHI) alternating with layers of anionic electrocatalytic materials (sulfonated copper phthalocyanine, CuPcS or gold nanoparticles, AuNP). Films with different layer structures were successfully formed. Characterization of surface roughness and porosity was carried out using AFM. Electrochemical responses towards catechol showed that the LbL composites efficiently improved the electron transfer path between Tyr or Lac and the electrode surface, producing an increase in the intensity over the response in the absence of the LbL platform. LbL structures with higher roughness and pore size facilitated the diffusion of catechol, resulting in lower LODs. The [(CHI)-(AuNP)-(CHI)-(CuPcS)]2-Tyr showed an LOD of 8.55∙10−4 μM, which was one order of magnitude lower than the 9.55·10−3 µM obtained with [(CHI)-(CuPcS)-(CHI)-(AuNP)]2-Tyr, and two orders of magnitude lower than the obtained with other nanostructured platforms. It can be concluded that the combination of adequate materials with complementary activity and the control of the structure of the platform is an excellent strategy to obtain biosensors with improved performances.Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (project RTI2018-097990-B-100)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA275P18)Infraestructuras Red de Castilla y León (grant UVA01

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

Landscape-induced spatial oscillations in population dynamics

We study the effect that disturbances in the ecological landscape exert on the spatial distribution of a population that evolves according to the nonlocal FKPP equation. Using both numerical and analytical techniques, we explore the three types of stationary profiles that can develop near abrupt spatial variations in the environmental conditions vital for population growth: sustained oscillations, decaying oscillations and exponential relaxation towards a flat profile. We relate the wavelength and decay length of the wrinkles to the shape of the interaction kernel. Since these spatial structures encode details about the interaction among individuals, we discuss how heterogeneities reveal information that would be hidden in a flat landscape

Electrochemical sensors modified with combinations of sulfur containing phthalocyanines and capped gold nanoparticles: A study of the influence of the nature of the interaction between sensing materials

Producción CientíficaVoltametric sensors formed by the combination of a sulfur-substituted zinc phthalocyanine (ZnPcRS) and gold nanoparticles capped with tetraoctylammonium bromide (AuNPtOcBr) have been developed. The influence of the nature of the interaction between both components in the response towards catechol has been evaluated. Electrodes modified with a mixture of nanoparticles and phthalocyanine (AuNPtOcBr/ZnPcRS) show an increase in the intensity of the peak associated with the reduction of catechol. Electrodes modified with a covalent adduct-both component are linked through a thioether bond-(AuNPtOcBr-S-ZnPcR), show an increase in the intensity of the oxidation peak. Voltammograms registered at increasing scan rates show that charge transfer coefficients are different in both types of electrodes confirming that the kinetics of the electrochemical reaction is influenced by the nature of the interaction between both electrocatalytic materials. The limits of detection attained are 0.9 × 10−6 mol∙L−1 for the electrode modified with the mixture AuNPtOcBr/ZnPcRS and 1.3 × 10−7 mol∙L−1 for the electrode modified with the covalent adduct AuNPtOcBr-S-ZnPcR. These results indicate that the establishment of covalent bonds between nanoparticles and phthalocyanines can be a good strategy to obtain sensors with enhanced performance, improving the charge transfer rate and the detection limits of voltammetric sensors.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (projects RTI2018-097990-B-I00 / CTQ2017-87102-R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA275P18