Dispositivos electroanalíticos miniaturizados: estrategías para la mejora de la separación y la detección

Tesis doctoral por el sistema de Compendio de PublicacionesActualmente, la miniaturización es una de las principales tendencias en todos los campos científicos y particularmente en la Química Analítica. En este contexto, las técnicas de separación y especialmente la electroforesis, han sido pioneras en el desarrollo de dispositivos analíticos miniaturizados (Microchips de Electroforesis, MEs). Estos se incluyen dentro de los dispositivos denominados ¿lab-on-a-chip¿ (LOC), capaces de integrar todas las etapas de análisis en un dispositivo portátil. En lo que se refiere a su aplicación clínica, también pueden considerarse dispositivos ¿point-of-care¿ (POC), desarrollados con el objetivo de realizar análisis descentralizados en el punto de diagnóstico o tratamiento. Con el fin de obtener dispositivos con altas prestaciones analíticas, el trabajo realizado en la presente memoria puede ser estructurado en tres partes: la modificación de los microcanales (para mejorar la selectividad), la obtención de un sistema de detección electroquímico miniaturizado y competitivo (para mejorar la sensibilidad), y la introducción de nuevos materiales (con el fin de obtener ¿zero-cost¿ análisis). Los microchips de electroforesis son dispositivos analíticos miniaturizados que pretenden ser una potente herramienta de análisis. La separación de los analitos va a depender de dos factores: (i) los fenómenos electrocinéticos, que vienen determinados en gran medida por la acumulación de cargas en la pared del microcanal y (ii) de la interacción de los analitos con el material inmovilizado. Por ello es de gran importancia la modificación superficial de los microcanales, especialmente cuando se trata de analitos con una relación masa/carga parecida. Las estrategias propuestas en esta memoria para la consecución de este objetivo pueden ser clasificadas en dos grandes grupos: modificaciones estáticas y modificaciones dinámicas, dependiendo de si son irreversibles o si se producen por adición del modificador a la disolución reguladora (fase pseudoestacionaria). A lo largo de los estudios aquí realizados se han evaluado polímeros comerciales [poli(ácido acrílico)], polímeros de síntesis propia derivados del poli(glicidil metacrilato) y modificadores orgánicos de reciente introducción (líquidos iónicos). Todos ellos han demostrado ser necesarios para conseguir la separación de especies estructuralmente muy parecidas, como son las catecolaminas (moléculas además de gran interés desde el punto de vista clínico dada su relación con enfermedades como por ejemplo el Alzheimer). Debido a los pequeños volúmenes de muestra empleados, estos dispositivos miniaturizados requieren un sistema de detección muy sensible. En los estudios recogidos en esta Tesis los nanotubos de carbono crecidos directamente sobre la superficie han demostrado ser un material electródico apropiado para la detección de las catecolaminas. Dado que la medida que se realiza es una medida electroquímica interfacial, el estado de la superficie es muy importante. Por ello, se evaluó la influencia de distintos parámetros como el empleo de catalizadores y capas intermedias, pretratamientos, o la densidad e influencia de la orientación de los nanotubos en la señal electroquímica. Por otro lado, la detección electroquímica ofrece muchas posibilidades, entre ellas el empleo de electrodos miniaturizados y de series de electrodos o ¿arrays¿ para obtener la señal analítica. Esta estrategia, permite además la obtención de mejores sensibilidades. Así, se describen los primeros pasos y pruebas hacia la consecución de este objetivo mediante el diseño de máscaras por métodos fotolitográficos. La parte final de esta Tesis está basada en la integración de la detección electroquímica en dispositivos analíticos miniaturizados realizados en materiales de bajo coste, los denominados ¿paper-based analytical devices¿. Así, se han evaluado tanto papel de filtro como transparencias, demostrando su potencial en la detección de metales pesados como el plomo o el cadmio

Analysis of relevant technical issues and deficiencies of the existing sensors and related initiatives currently set and working in marine environment. New generation technologies for cost-effective sensors

The last decade has seen significant growth in the field of sensor networks, which are currently collecting large amounts of environmental data. This data needs to be collected, processed, stored and made available for analysis and interpretation in a manner which is meaningful and accessible to end users and stakeholders with a range of requirements, including government agencies, environmental agencies, the research community, industry users and the public. The COMMONSENSE project aims to develop and provide cost-effective, multi-functional innovative sensors to perform reliable in-situ measurements in the marine environment. The sensors will be easily usable across several platforms, and will focus on key parameters including eutrophication, heavy metal contaminants, marine litter (microplastics) and underwater noise descriptors of the MSFD. The aims of Tasks 2.1 and 2.2 which comprise the work of this deliverable are: • To obtain a comprehensive understanding and an up-to-date state of the art of existing sensors. • To provide a working basis on “new generation” technologies in order to develop cost-effective sensors suitable for large-scale production. This deliverable will consist of an analysis of state-of-the-art solutions for the different sensors and data platforms related with COMMONSENSE project. An analysis of relevant technical issues and deficiencies of existing sensors and related initiatives currently set and working in marine environment will be performed. Existing solutions will be studied to determine the main limitations to be considered during novel sensor developments in further WP’s. Objectives & Rationale The objectives of deliverable 2.1 are: • To create a solid and robust basis for finding cheaper and innovative ways of gathering data. This is preparatory for the activities in other WPs: for WP4 (Transversal Sensor development and Sensor Integration), for WP(5-8) (Novel Sensors) to develop cost-effective sensors suitable for large-scale production, reducing costs of data collection (compared to commercially available sensors), increasing data access availability for WP9 (Field testing) when the deployment of new sensors will be drawn and then realized

Investigation of Volatile Organic Compounds (VOCs) released as a result of spoilage in whole broccoli, carrots, onions and potatoes with HS-SPME and GC-MS

Vegetable spoilage renders a product undesirable due to changes in sensory characteristics. The aim of this study was to investigate the change in the fingerprint of VOC composition that occur as a result of spoilage in broccoli, carrots, onions and potatoes. SPME and GC-MS techniques were used to identify and determine the relative abundance of VOC associated with both fresh and spoilt vegetables. Although a number of similar compounds were detected in varying quantities in the headspace of fresh and spoilt samples, certain compounds which were detected in the headspace of spoilt vegetables were however absent in fresh samples. Analysis of the headspace of fresh vegetables indicated the presence of a variety of alkanes, alkenes and terpenes. Among VOCs identified in the spoilt samples were dimethyl disulphide and dimethyl sulphide in broccoli; Ethyl propanoate and Butyl acetate in carrots; 1-Propanethioland 2-Hexyl-5-methyl-3(2H)-furanone in onions; and 2, 3-Butanediol in potatoes. The overall results of this study indicate the presence of VOCs that can serve as potential biomarkers for early detection of quality deterioration and in turn enhance operational and quality control decisions in the vegetable industry

Detection of Pathogens in Water Using Micro and Nano-Technology

Detection of Pathogens in Water Using Micro and Nano-Technology aims to promote the uptake of innovative micro and nano-technological approaches towards the development of an integrated, cost-effective nano-biological sensor useful for security and environmental assays.  The book describes the concerted efforts of a large European research project and the achievements of additional leading research groups. The reported knowledge and expertise should support in the innovation and integration of often separated unitary processes. Sampling, cell lysis and DNA/RNA extraction, DNA hybridisation detection micro- and nanosensors, microfluidics, together also with computational modelling and risk assessment can be integrated in the framework of the current and evolving European regulations and needs. The development and uptake of molecular methods is revolutionizing the field of waterborne pathogens detection, commonly performed with time-consuming cultural methods. The molecular detection methods are enabling the development of integrated instruments based on biosensor that will ultimately automate the full pathway of the microbiological analysis of water

Detection of Pathogens in Water Using Micro and Nano-Technology

Detection of Pathogens in Water Using Micro and Nano-Technology aims to promote the uptake of innovative micro and nano-technological approaches towards the development of an integrated, cost-effective nano-biological sensor useful for security and environmental assays.  The book describes the concerted efforts of a large European research project and the achievements of additional leading research groups. The reported knowledge and expertise should support in the innovation and integration of often separated unitary processes. Sampling, cell lysis and DNA/RNA extraction, DNA hybridisation detection micro- and nanosensors, microfluidics, together also with computational modelling and risk assessment can be integrated in the framework of the current and evolving European regulations and needs. The development and uptake of molecular methods is revolutionizing the field of waterborne pathogens detection, commonly performed with time-consuming cultural methods. The molecular detection methods are enabling the development of integrated instruments based on biosensor that will ultimately automate the full pathway of the microbiological analysis of water

Biomimetic Based Applications

The interaction between cells, tissues and biomaterial surfaces are the highlights of the book "Biomimetic Based Applications". In this regard the effect of nanostructures and nanotopographies and their effect on the development of a new generation of biomaterials including advanced multifunctional scaffolds for tissue engineering are discussed. The 2 volumes contain articles that cover a wide spectrum of subject matter such as different aspects of the development of scaffolds and coatings with enhanced performance and bioactivity, including investigations of material surface-cell interactions