Polímeros sensores: aplicaciones como sensores químicos en detección y cuantificación de analitos

La tesis doctoral describe la preparación de nuevos materiales poliméricos para la detección colorimétrica y/o fluorimétrica de distintos contaminantes y moléculas de interés. Los nuevos polímeros sensores se han diseñado en forma de polímero entrecruzado (membrana, film), así como en forma de polímero lineal (sólido soluble en agua). Estos materiales avanzados cambian de color en presencia de contaminantes como el cianuro, o el hierro (III); y son capaces de generar fluorescencia en presencia de aluminio (III), cromo (VI), mercurio (II) y distintas moléculas de interés biomédico como el coenzima A. Como es natural, los fenómenos de detección en sistemas biológicos se dan en medios acuosos. Por ejemplo, los sitios activos en las enzimas tienen la forma requerida para alojar a la molécula huésped, o parte de ella, y la interacción se basa en enlaces débiles que tienen lugar debido a los dominios hidrofóbicos en un entorno hidrofílico general. En un intento de imitar a la naturaleza, se pueden anclar receptores insolubles en agua, lipofílicos, a cadenas lineales o reticuladas de polímeros hidrofílicos, dando lugar a polímeros sensores solubles en agua o a materiales sensores hinchados en este medio, con comportamiento tipo gel. Esta última aproximación al fenómeno sensor permite el control del hinchamiento por medio del incremento o disminución de la densidad de nudos, denominada relación nominal de entrecruzamiento. Es decir, el carácter hidrofílico del polímero, relacionado con la constitución de los monómeros, se puede controlar no sólo mediante la naturaleza de los comonómeros utilizados en la síntesis del material, sino también a través del porcentaje de entrecruzante empleando en la síntesis, facilitando o disminuyendo la absorción de agua. Así, se puede inducir un carácter hidrofóbico a una estructura polimérica hidrofílica mediante la tensión de la red tridimensional en el proceso de hinchamiento con agua

Estudio de la reducción de emisión de formaldehído en las resinas de urea formaldehído

En el siguiente trabajo se estudiaron las emisiones de formaldehído que provocan los tableros de partículas fabricados con resinas de urea-formaldehído. En el trabajo se realizo un diseño de experimentos de tipo central compuesto, para obtener unas condiciones de fabricación de resina optimas con el objetivo de reducir al máximo el contenido en formaldehído, sin que éste pierda sus propiedades mecánicas

Isolation and Quantification of Mandelonitrile from Arabidopsis thaliana Using Gas Chromatography/Mass Spectrometry

ProtocoloMandelonitrile is a nitrogen-containing compound, considered an essential secondary metabolite. Chemically, it is a cyanohydrin derivative of benzaldehyde, with relevant functions in different physiological processes including defense against phytophagous arthropods. So far, procedures for detecting mandelonitrile have been effectively applied in cyanogenic plant species such as Prunus spp. Nevertheless, its presence in Arabidopsis thaliana, considered a non-cyanogenic species, has never been determined. Here, we report the development of an accurate protocol for mandelonitrile quantification in A. thaliana within the context of A. thaliana–spider mite interaction. First, mandelonitrile was isolated from Arabidopsis rosettes using methanol; then, it was derivatized by silylation to enhance detection and, finally, it was quantified using gas chromatography–mass spectrometry. The selectivity and sensitivity of this method make it possible to detect low levels of mandelonitrile (LOD 3 ppm) in a plant species considered non-cyanogenic that, therefore, will have little to no cyanogenic compounds, using a small quantity of starting material (≥ 100 mg).This work was supported by funds of “La Caixa” Foundation (LCF/PR18/51130007) and Ministerio de Universidades-European Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid)

Smart Polymers for Food and Water Quality Control and Safety

A large number of annual cases of diseases and deaths related to spoiled or contaminated food, and the amount of food waste are a matter of socio-economic impact, highlighting the need for a fast, easy, cheap, available, and real-time determination of food quality and safety. To ensure this, physical and chemical food quality indicators such as humidity, temperature, gases, pH, microorganisms, pesticides, etc., should be controlled and monitored during production, transportation, storage, and consumption. In this sense, smart polymers are raised as useful tools to facilitate this task. These polymers are sensitive to variations in the microenvironment, modifying their properties and/or generating a response that can be measured. Due to their versatility, these materials can be part of the food packaging to inform the consumers or be used as a measuring tool to determine the state of the food. This chapter envisaged the concept of smart polymers, the types, and their main applications for determining food quality and ensuring food and beverage safety.We gratefully acknowledge the financial support provided by FEDER (Fondo Europeo de Desarrollo Regional), the Spanish AEI (State Research Agency, PID2020-113264RBI00/AEI/10.13039/501100011033 and PID2019-108583RJI00/AEI/10.13039/501100011033), and "La Caixa" Foundation (under agreement LCF/PR/PR18/51130007). We also acknowledge the financial support provided by the Spanish Ministerio de Universidades (Plan de Recuperación, Transformación y Resiliciencia, European Union-NextGenerationEU, Universidad Politécnica de Madrid (RD 289/2021) and Universidad Autónoma de Madrid (CA1/RSUE/2021-00409))

Film-shaped reusable smart polymer to produce lactose-free milk by simple immersion

In this study, we report the synthesis and characterization of a highly manageable polyacrylic film material for enzyme immobilization, using β-galactosidase (β-gal) as a model enzyme. The material is based on commercially available monomers and achieves efficient immobilization of β-gal through the formation of azo linkages between amino styrene groups in the polyacrylic material and the enzyme. The immobilized enzyme demonstrates superior performance compared to free enzyme in lactose hydrolysis of UHT milk, achieving lactose concentrations below 0.1% (<1 mg/mL), indicating its potential for lactose hydrolysis in dairy products. The film-shaped material is designed for easy submersion and removal, similar to a smart card, and offers reusability, with the ability to be reused at least 10 times without loss of enzymatic activity. Characterization of the immobilized enzyme on the polymeric material was performed using various techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. Protein release studies confirmed the stability of the immobilized enzyme during prolonged incubation in aqueous solution without significant enzyme leakage. Overall, the polyacrylic film material demonstrates promise as a simple and efficient approach for enzyme immobilization, with potential applications in various industries, including the food industry.We gratefully acknowledge the financial support provided by all funders. This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGenerationEU PRTR. Author J. M. García received grant PID2020-113264RB-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. A. Arnaiz received funding from Ministerio de Universidades-European Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid). J. L. Vallejo-García received the grant PRE2021-09812 funded by MCIN/AEI/ 10.13039/501100011033 and by “ESF Investing in your future”. Author Saul Vallejos received grant BG22/00086 funded by Spanish Ministerio de Universidades

Smart polymers in micro and nano sensory devices

The present review presents the most recent developments concerning the application of sensory polymers in the detection and quantification of different target species. We will firstly describe the main polymers that are being employed as sensory polymers, including, for example, conducting or acrylate-based polymers. In the second part of the review, we will briefly describe the different mechanisms of detection and the target species, such as metal cations and anions, explosives, and biological and biomedical substances. To conclude, we will describe the advancements in recent years concerning the fabrication of micro and nano sensory devices based on smart polymers, with a bibliographic revision of the research work published between 2005 and today, with special emphasis on research work presented since 2010. A final section exposing the perspectives and challenges of this interesting research line will end the present review article.FEDER (Fondo Europeo de DEsarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2014-54137-R, MAT2017-84501-R) and the Consejería de Educación–Junta de Castilla y León (BU061U16

Metal-free organocatalysts for high hydrolytic stability single component polyurethane adhesives and their application in decorative insulation facades manufacturing

We focused on developing polyurethane (PU) adhesives with superior ambient thermal and hydrolytic stability, a crucial factor for industrial productivity. Our approach involved creating PU prepolymers that can withstand varying temperatures in ambient conditions. These prepolymers consist of conventional isocyanate-terminated polyurethane and metal-free acid:base organic catalysts, with the stability of the adhesive relying on the organocatalyst employed. We tested a series of 11 latent organocatalysts derived from the reaction between 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and various acids. Among these, the catalyst based on 1-naphthoic acid exhibited exceptional stability, lasting at least 3 h at 60 ◦C and an average relative humidity of 65% under vigorous stirring. We assessed this stability using a fan-based stirrer and analyzed the curing conditions kinetically through DSC. Furthermore, our adhesive formulation is environmentally friendly as it is free of metals, specifically tin (typically present in catalysts such as dibutyltin dilaurate). This quality enhances its sustainability. To validate the practical applicability of the adhesives, we conducted tests using decorative facade models composed of siliciclastic sandstone extracted from a quarry in Vilviestre del Pinar (Burgos, Spain. Latitude: 41.951024◦N, longitude: 3.078283◦W) and extruded polystyrene (XPS). The results demonstrated the excellent hydrolytic and thermal stability of the adhesives, highlighting their significant potential for panel manufacturing in this context.This work was supported by the Regional Government of Castilla y León (Junta de Castilla y León) and by the Ministry of Science and Innovation MICIN and the European Union NextGeneration EU PRTR. Author José Miguel García received grant PID2020-113264RB-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Author Miriam Trigo-López received grant PID2019-108583RJ-I00 funded by MCIN/AEI/10.13039/501100011033. Author Saul Vallejos received grant BG22/00086 funded by Spanish Ministerio de Universidades

An Organic/Inorganic Hybrid Membrane as a Solid “Turn-On” Fluorescent Chemosensor for Coenzyme A (CoA), Cysteine (Cys), and Glutathione (GSH) in Aqueous Media

The preparation of a fluorogenic sensory material for the detection of biomolecules is described. Strategic functionalisation and copolymerisation of a water insoluble organic sensory molecule with hydrophilic comonomers yielded a crosslinked, water-swellable, easy-to-manipulate solid system for water ‘‘dip-in’’ fluorogenic coenzyme A, cysteine, and glutathione detection by means of host-guest interactions. The sensory material was a membrane with gel-like behaviour, which exhibits a change in fluorescence behaviour upon swelling with a water solution of the target molecules. The membrane follows a “turn-on” pattern, which permits the titration of the abovementioned biomolecules. In this way, the water insoluble sensing motif can be exploited in aqueous media. The sensory motif within the membrane is a chemically anchored piperazinedione-derivative with a weakly bound Hg(II). The response is caused by the displacement of the cation from the membrane due to a stronger complexation with the biomolecules, thus releasing the fluorescent sensory moieties within the membraneSpanish Ministerio de Ciencia e Innovación—Feder (MAT2011-22544) and by the Junta de Castilla y León (BU001A10-2

Polymer-based chemical sensors

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Polymer films containing chemically anchored diazonium salts with long-term stability as colorimetric sensors

We have prepared polymeric films as easy-to-handle sensory materials for the colorimetric detection and quantification of phenol derivatives (phenols) in water. Phenols in water resources result from their presence in pesticides and fungicides, among other goods, and are harmful ecotoxins. Colorless polymeric films with pendant diazonium groups attached to the acrylic polymer structure were designed and prepared for use as sensory matrices to detect phenol-derived species in water. Upon dipping the sensory films into aqueous media, the material swells, and if phenols are present, they react with the diazonium groups of the polymer to render a highly colored azo group, giving rise to the recognition phenomenon. The color development can be visually followed for a qualitative determination of phenols. Additionally, quantitative analysis can be performed by two different techniques: a) by using a UV–vis spectrophotometer (limit of detection of 0.12 ppm for 2-phenylphenol) and/or b) by using a smartphone with subsequent RGB analysis (limit of detection of 30 ppb for 2-phenylphenol)Fondo Europeo de Desarrollo Regional (FEDER) and the Spanish Agencia Estatal de Investigación (AEI) (MAT2017-84501-R