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

Polymeric chemosensor for the colorimetric determination of the total polyphenol index (TPI) in wines

We have developed a new method for the rapid and inexpensive determination of the total polyphenol index (TPI) in wines by simply immersing our sensory film in red or white wines and visually checking the colour change (qualitative analysis) or by analysing a photo taken of the film with a smartphone (quantitative analysis). This sensory material is straightforward and inexpensively prepared; it requires no monomer synthesis, is based on 100% commercially available monomers, and contains benzenediazonium salt motifs, which in the presence of phenols and/or polyphenol-based structures produce coloured diazo compounds. These sensory motifs are chemically anchored to the polymeric structure, and, accordingly, no migration of organic substances from the material occurs in the sensing process. Our method needs neither reagents nor sample pretreatment and has been contrasted with the standard TPI determination, i.e., measuring the absorbance of diluted wine at 280 nm, obtaining reliable data for white and red wines.Fondo Europeo de Desarrollo Regional and both the Spanish Agencia Estatal de Investigación (MAT2017-84501-R) and the Consejería de Educación, Junta de Castilla y León (BU306P18

Zn(II) detection in biological samples with a smart sensory polymer

We have developed a new sensory material for the rapid and inexpensive determination of Zn(II), and we have carried out a proof of concept for the determination of Zn(II) in biological samples. The interaction with Zn(II) generates an OFF-ON fluorescence process on the material, which can be recorded both with a fluorimeter and with a smartphone by analyzing the RGB components of the taken photographs. This sensory material is prepared with 99.75% of commercially available monomers and contains 0.25% of a sensory monomer based on a quinoline structure. The sensory motifs are chemically anchored to the polymeric structure, and, accordingly, no migration of organic substances from the material occurs during the sensing process. Our method has been tested with freshly prepared Zn(II) aqueous solutions, but also with biological samples from exudates of chronic wounds. The proposed methodology provides limits of detection (LOD) of 13 and 27 ppb when employing a water-soluble polymer (WsP) and a hydrophilic polymeric film (HP), respectively, using emission spectroscopy. The measurements have been contrasted with ICP-MS as the reference method, obtaining reliable data. This study is the starting point toward a larger investigation with patients, which will address the challenge of establishing a direct relationship between the concentration of zinc(II), other cations and also of amino acids, with the protease activity and, finally, with the state/evolution of chronic wounds. In this context, the proposed sensory material and others we are now working with will act as a simple and cheap method for this purpose.FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2017-84501-R) and the Consejería de Educación—Junta de Castilla y León (BU061U16

Why is the Sensory Response of Organic Probes within a Polymer Film Different in Solution and in the Solid-State? Evidence and Application to the Detection of Amino Acids in Human Chronic Wounds

We anchored a colourimetric probe, comprising a complex containing copper (Cu(II)) and a dye, to a polymer matrix obtaining film‐shaped chemosensors with induced selectivity toward glycine. This sensory material is exploited in the selectivity detection of glycine in complex mixtures of amino acids mimicking elastin, collagen and epidermis, and also in following the protease activity in a beefsteak and chronic human wounds. We use the term inducing because the probe in solution is not selective toward any amino acid and we get selectivity toward glycine using the solid‐state. Overall, we found that the chemical behaviour of a chemical probe can be entirely changed by changing its chemical environment. Regarding its behaviour in solution, this change has been achieved by isolating the probe by anchoring the motifs in a polymer matrix, in an amorphous state, avoiding the interaction of one sensory motif with another. Moreover, this selectivity change can be further tuned because of the effectiveness of the transport of targets both by the physical nature of the interface of the polymer matrix/solution, where the target chemicals are dissolved, for instance, and inside the matrix where the recognition takes place. The interest in chronic human wounds is related to the fact that our methods are rapid and inexpensive, and also considering that the protease activity can correlate with the evolution of chronic wounds.FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2017‐84501‐R) and the Consejería de Educación—Junta de Castilla y León (BU061U16

Colorimetric detection and determination of Fe(III), Co(II), Cu(II) and Sn(II) in aqueous media by acrylic polymers with pendant terpyridine motifs

Colorimetric cation responsive water soluble polymers and manageable films or membranes have beendesigned. The sensory materials respond with a colour change to the presence in water of Fe(III), Co(II),Cu(II), and Sn(II). The colour change is specific of each metal cation, and enables its identification (purplefor iron, orange for cobalt, green for copper, and yellow for tin). The design of the materials relies onan addition monomer having a terpyridine moiety, which behaves as a dye in presence of transitionmetal cations due to its proven chelating capability towards these species and the colour developmentthat always accompany the metallic complex formation. Water solutions of the sensory linear polymersallow for the UV/vis titration of Fe(III), Co(II), Cu(II), and Sn(II) with a limit of detection of 1.3 × 10−7,6.4 × 10−8, 1.3 × 10−5and 1.4 × 10−5M, respectively. On the other hand, sensory kits, cut from sensorymembranes, permitted the visual quantification of the cations in a dynamic range of five decades (1 × 10−7to 5 × 10−3M) for Fe(III) and Co(II) and of two decades (9 × 10−5to 9 × 10−3M) for Cu(II) and Sn(II).Titration curves can also be drawn from a picture taken to the sensory kits with a smartphone, by usingthe digital colour definition of the materials as analytical signal. Also, after entering into contact withhands, shapes of metallic objects (iron and cobalt containing tools) can be colour revealed by pressingthe hands on paper or cotton fabrics wetted with water solutions of the linear sensory polymer.Spanish Ministerio deEconomía y Competitividad-Feder (MAT2014-54137-R

Polímeros inteligentes para la detección rápida, sencilla y de bajo coste de nitritos en muestras de carne procesada

Los nitritos son aditivos muy utilizados en alimentación, principalmente en productos cárnicos crudos curados y cocidos. Se emplean para prolongar su vida útil, debido a que inhiben el crecimiento de diversos patógenos, destacando su acción sobre la bacteria Clostridium botulinum. La legislación actual establece la cantidad permitida de nitritos en matrices alimentarias de origen cárnico, por lo que su cuantificación es necesaria. Sin embargo, el método de análisis de este grupo de especies resulta tedioso y supone un coste económico y de tiempo muy elevado. Por ello, en este trabajo se describe un nuevo método de análisis basado en un polímero inteligente, concretamente en un sensor colorimétrico para la detección de nitritos en muestras de carne procesada. Este material permite determinar la concentración de estos aditivos a partir del cambio de color del propio material sensor al contacto directo con la matriz alimentaria. Esta variación cromática se puede analizar de manera rápida y sencilla a partir de una simple fotografía tomada con la cámara de un teléfono al polímero sensor. Además, se ha desarrollado una aplicación para teléfonos inteligentes que facilita todo el proceso, obteniendo directamente el resultado de la concentración de nitritos que contiene el producto a partir de la mencionada fotografía. El nuevo método de análisis se ha validado comparando los resultados obtenidos con un método de referencia (ISO 2918: 1975). Esta validación se ha llevado a cabo analizando 26 muestras de productos cárnicos de diferente naturaleza y procedencia (8 de ellas corresponden a jamones cocidos de elaboración propia en las instalaciones de la Universidad de Burgos, con concentraciones conocidas de nitritos, y otras 18 son muestras comerciales de concentraciones de nitritos desconocidas, entre las que se encuentran carnes frescas envasadas, jamones y salchichas cocidos). Como resultado principal, cabe indicar que no se han observado diferencias estadísticas significativas entre los resultados obtenidos con el método de referencia de medida de nitritos y el nuevo método que se propone en este trabajo, por lo que se puede considerar como una alternativa viable que supone un ahorro significadito de costes y de tiempo

Aromatic polyamides and acrylic polymers as solid sensory materials and smart coated fibres for high acidity colorimetric sensing

We synthesized a solid sensory material for the extraction, detection and quantification of iron(III) in aqueous media. The material is a film-shaped colorless polymer membrane that exhibits gel behavior. The Fe(III) extraction and sensing characteristics are imparted by a new monomer derived from a natural product (i.e., Kojic acid), which exhibits chelating properties toward Fe(III). The sorption of Fe(III) on the membrane in water has been thoroughly characterized, including the sorption kinetics, sorption isotherms and profiles as a function of the pH. Fe(III) sorption followed pseudo first-order kinetics and required approximately 30 min to reach equilibrium. The maximum sorption capacity was approximately 0.04 mmol/g, and the sorption isotherms are well modeled by the Langmuir equation. The complexes that were found in the solid phase are in good agreement with those previously identified in the aqueous phase. Moreover, the sorption is highly specific (i.e., a recognition process) and results from the formation of a colored complex (iron(III)-Kojic acid derivative moieties). Therefore, the colorless sensory membrane turns red upon immersion in aqueous solutions containing Fe(III). The color output allows for both the qualitative visual determination of the Fe(III) concentration as well as also titration of Fe(III) using a) a UV/vis technique (limit of detection of 3.6 × 10−5 M; dynamic range of five decades, lower concentration = 1.65 × 10−6 M) and b) a computer vision-based analytical chemistry approach via color definition of the sensory membrane (RGB parameters) obtained from an image recorded with a handy device (e.g., a smartphone) (limit of detection of 2.0 × 10−5 M).Spanish Ministerio de Economía y Competitividad-Feder (MAT2011-22544 and MAT2014-54137-R) and by the Consejería de Educación – Junta de Castilla y León (BU232U13

Forced Solid-State Interactions for the Selective “Turn-On” Fluorescence Sensing of Aluminum Ions in Water Using a Sensory Polymer Substrate

Selective and sensitive solid sensory substrates for detecting Al(III) in pure water are reported. The material is a flexible polymer film that can be handled and exhibits gel behavior and membrane performance. The film features a chemically anchored salicylaldehyde benzoylhydrazone derivative as an aluminum ion fluorescence sensor. A novel procedure for measuring Al(III) at the ppb level using a single solution drop in 20 min was developed. In this procedure, a drop was allowed to enter the hydrophilic material for 15 min before a 5 min drying period. The process forced the Al(III) to interact with the sensory motifs within the membrane before measuring the fluorescence of the system. The limit of detection of Al(III) was 22 ppm. Furthermore, a water-soluble sensory polymer containing the same sensory motifs was developed with a limit of detection of Al(III) of 1.5 ppb, which was significantly lower than the Environmental Protection Agency recommendations for drinking water.Spanish Ministerio de Economía y Competitividad-Feder (MAT2011-22544) and by the Consejería de Educación - Junta de Castilla y León (BU232U13)

La interdisciplinariedad y el itinerario curricular elegido por el estudiante, ejes fundamentales para desarrollar competencias curriculares en Química

Póster presentado en: V Jornadas de Innovación Docente de la UBU, Burgos, 21-22 de octubre de 2010, organizadas por el Instituto de Formación e Innovación Educativa-IFIE de la Universidad de Burgo