Isasi-Allica, J.R. (José Ramón)
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- Chitosan, xanthan and locust bean gum matrices crosslinked with β-cyclodextrin as green sorbents of aromatic compounds(Elsevier, 2021) Isasi-Allica, J.R. (José Ramón); Petitjean, M. (Max)Three different polysaccharides, xanthan gum, chitosan and locust bean gum, were crosslinked with or without β-cyclodextrin, using citric acid in different ratios, to create ‘green’ hydrogel matrices. The crosslinking of these polysaccharides was produced through an inexpensive and innocuous solvent-free synthesis process. A favorable swelling behavior of the hydrophilic matrices facilitates the sorption of the solutes tested. Interestingly, the amount of β-cyclodextrin groups is not the only factor to yield the best sorption capability for hydrophobic model molecules: polysaccharides themselves also influence the sorption depending on their characteristic functional groups, the conformation of their chains and, as mentioned above, their degrees of swelling. In order to ascertain the effect of the polysaccharides on the sorption capabilities of a model sorbate (1-naphthol), isotherms using a wide range of solute concentrations were analyzed, and the Hill equation yielded the best fitting results and provided some insight into the mechanisms of interaction.
- Incorporación de vídeos e infográficos de interés a la docencia en Química(2013-02-11) Isasi-Allica, J.R. (José Ramón); González-Gaitano, G. (Gustavo); Sirera-Bejarano, R. (Rafael); Alvarez-Galindo, J.I. (José Ignacio); Duran-Benito, A. (Adrian); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)- Búsqueda en la web de elementos audiovisuales – vídeos – e infográficos relevantes, concomitantes y de calidad. Se estima una selección de cinco a diez vídeos/infográficos por cada materia/profesor participante en el proyecto (del grado en Química relacionadas con la Química Inorgánica, Química Analítica y Química Física) (julio, agosto y comienzos de septiembre). - Inclusión de los mismos en la programación docente de la materia. Proyección en el aula en el contexto del tema adecuado. Explicación previa de los contenidos fundamentales del vídeo/infográfico y su relación con el tema en esos momentos abordado en la materia. - Feed-back del proyecto mediante alumnos que, voluntariamente, quieran referir en un breve cuestionario escrito su impresión sobre los vídeos proyectados o infográficos visionados, interés, grado de incentivación del estudio que se consigue con ello, etc.
- Locust bean gum, a vegetable hydrocolloid with industrial and biopharmaceutical applications(2022) Isasi-Allica, J.R. (José Ramón); Petitjean, M. (Max)Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.
- Innovative teaching strategies applied to university courses in Chemistry(Edulab, 2014-05-04) Isasi-Allica, J.R. (José Ramón); González-Gaitano, G. (Gustavo); Sirera-Bejarano, R. (Rafael); Alvarez-Galindo, J.I. (José Ignacio); Duran-Benito, A. (Adrian); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)Audiovisual media are nowadays appropriate tools to help illustrate the development of lectures by university professors. The 21st century students use them at ease, finding them an excellent companion to study certain subject topics. In particular, in the field of experimental sciences –as Chemistry- the advantages of using these materials are clear, both in portraying in a more visible way some abstract concepts and related phenomena and in the student's own approach to more practical aspects related to professional skills and practice upon completion of studies. This paper evaluates the results of applying the new technologies in the teaching of chemistry to undergraduate students of the University of Navarra. It also aims to target examples of the professional day to day activity of a Chemist and provide sound theoretical background as well as practical approaches to problem-solving tasks in any areas of Chemistry. Students’ perception has certainly been positive in terms of an increase of interest for the topics involved and well as an improved understanding of them.
- Preparation of beta-cyclodextrin/polysaccharide foams using saponin(2023) Isasi-Allica, J.R. (José Ramón); Petitjean, M. (Max)Cyclodextrins, cyclic oligosaccharides with a hydrophobic cavity that form inclusion complexes with nonpolar molecules, can be used to functionalize other polysaccharides. Xanthan gum, locust bean gum or chitosan can be crosslinked using citric acid in the presence of ß-cyclodextrin to produce insoluble matrices. In this work, polymeric foams based on those polysaccharides and saponin have been prepared using a green synthesis method to increase the porosity of the matrices. The saponin of soapbark (Quillaja saponaria) has been used to obtain foams using different procedures. The influence of the synthesis path on the porosity of the materials and their corresponding sorption capacities in the aqueous phase were evaluated.
- Estrategias de innovación docente en el aprendizaje de materias universitarias de química. Twentieth International Conference on Learning. Rodes, 2013(2013-10-11) Isasi-Allica, J.R. (José Ramón); González-Gaitano, G. (Gustavo); Sirera-Bejarano, R. (Rafael); Alvarez-Galindo, J.I. (José Ignacio); Duran-Benito, A. (Adrian); Navarro-Blasco, I. (Iñigo); Fernandez-Alvarez, J.M. (José María)Los medios audiovisuales son herramientas adecuadas hoy en día para ilustrar el desarrollo de las clases magistrales impartidas por el profesor universitario. El alumno se desenvuelve con soltura en estos soportes, y la utilización de estos medios es un óptimo complemento para una buena comprensión del tema. Particularizando esta acción en estudios experimentales, como la Química, las ventajas que aporta el empleo de estos materiales son claras, tanto en el entendimiento de los temas como en el propio acercamiento del alumno a aspectos más prácticos y relacionados con el ejercicio profesional al que se dedicarán cuando finalicen los estudios. El presente trabajo evalúa los resultados de aplicar las nuevas tecnologías en la enseñanza de la Química a estudiantes de la Universidad de Navarra. Se pretende identificar elementos propios del ejercicio profesional del químico y relacionar los contenidos teórico-prácticos de las asignaturas con el mismo, consiguiendo además con ello un mejor conocimiento de la materia objeto de estudio. La percepción de los alumnos ha sido ciertamente positiva en términos de un incremento de interés por las materias implicadas y de una mejora en la comprensión de las mismas.
- Removal of cresols from water by packed beds of cyclodextrin-based hydrogels(2022) Isasi-Allica, J.R. (José Ramón); Peñas-Esteban, F.J. (Francisco Javier); Romo‐Hualde, A. (Ana)A cyclodextrin-based polymer was prepared by crosslinking beta-cyclodextrin with epichlorohydrin to be assessed as a sorbent material for cresols in packed-bed columns. Both Langmuir and Freundlich isotherms were appropriate to describe the sorption equilibrium in the conditions tested, and the thermodynamic parameters obtained for this process confirmed its exothermic nature with similar enthalpies (between - 6.8 and - 8.3 kJ/mol) for the three isomers. The removal of cresols from water was carried out in nine cycles of sorption-desorption in fixed-column experiments with the cyclodextrin hydrogel, achieving sorption capacities of 6.2, 11.6, and 15.1 mg/g for o-, m-, p-cresol, respectively. These differences in sorption capacities are due to the different chemical structures of cresols, that is, the relative position of the methyl and hydroxyl groups. However, similar sorption rates were observed for each isomer, with a mean value of 0.10 mg-cresol g-CDP-1 min(-1) in all cases. The experimental data for the breakthrough and the elution curves have been successfully modeled by two effective two-parameter equations, a dose-response model for the sorption step and a pulse-peak model for the regeneration step. The cyclodextrin polymer matrix has been proven to be an effective a good sorbent material for removing cresols from water, exhibiting remarkable reusability performance and structural stability throughout the successive elution steps carried out with methanol.
- Phase behavior of reverse poloxamers and poloxamines in water(American Chemical Society, 2013) Isasi-Allica, J.R. (José Ramón); Larrañeta, E. (Eneko)The phase behavior of two types of poly(ethylene oxide)/ poly(propylene oxide) (PEO/PPO) copolymers in aqueous solutions was studied by light scattering, viscometry and infrared spectroscopy. Both the reverse poloxamer (Pluronic 10R5) and the star type poloxamine (Tetronic 90R4) have practically the same PEO/PPO ratio with their hydrophobic blocks (PPO) located in the outer part. The temperature-composition phase diagrams show that both 10R5 and 90R4 tend to form aggregates in water. Up to four different phases can be detected in the case of Tetronic 90R4 for each temperature: unimers, random networks, micellar networks and macrophase separation. Viscometric and infrared measurements complemented the results obtained by light scattering and visual inspection.
- Green synthesis and chemometric characterization of hydrophobic xanthan matrices: interactions with phenolic compounds(Elsevier, 2022) Isasi-Allica, J.R. (José Ramón); Zornoza, A. (Arantza); Petitjean, M. (Max); Lamberto, I. (Iranzu)Polysaccharides such as xanthan, locust bean gum or chitosan are easily crosslinked and purified using citric acid in an ecofriendly process. In order to achieve an improved sorption capability towards hydrophobic solutes, β-cyclodextrin, a cyclic oligosaccharide, and lignin, a natural aromatic polymer, are incorporated in the same process. Once crosslinked, the influence of these on the sorption capacities towards model solutes has been assessed by comparing the sorption isotherms of matrices with or without the hydrophobic modifications. The sorption capacities of these materials for different phenolic compounds have also been tested to ascertain their efficiencies as a function of their affinities to β-cyclodextrin cavities and/or their partition coefficients. In addition, these functionalized carbohydrate matrices were successfully characterized by principal component analysis, which is a useful tool to select the most appropriate polymers to interact with a specific molecule
- In-vitro release from reverse poloxamine/α-cyclodextrin matrices. Modelling and comparison of dissolution profiles(Wiley, 2014) Isasi-Allica, J.R. (José Ramón); Machin, R. (Rubén); Zornoza, A. (Arantza); Larrañeta, E. (Eneko); Vélaz-Rivas, I. (Icíar); Martinez-Oharriz, C. (Cristina)ABSTRACT: Gels obtained by complexation of octablock star PEO/PPO copolymers (Tetronic 90R4) with α-CD were evaluated as matrices for drug release. Both molecules are biocompatible so they can be potentially applied to drug delivery systems. Two different types of matrices of Tetronic 90R4 and α-CD were evaluated: gels and tablets. These gels are capable to gelifying in-situ and show sustained erosion kinetics in aqueous media. Tablets were prepared by freeze drying and comprising the gels. Using these two different matrices the release of two model molecules, L-Tryptophan (Trp), and a protein, bovine serum albumin (BSA), was evaluated. The release profiles of these molecules from gels and tablets prove that they are suitable for sustained delivery. Mathematical models were applied to the release curves from tablets in order to elucidate the drug delivery mechanism. Good correlations were found for the fittings of the release curves to different equations. The results point that the release of Trp from different tablets is always governed by Fickian diffusion while the release of BSA is governed by a combination of diffusion and tablet erosion.