Materials fets a mida : aerogels de sílice modificats orgànicament

Els aerogels són els materials sòlids més lleugers que es coneixen, degut al fet que la major part de la seva estructura és buida. La seva extraordinària porositat fa que tinguin una gran àrea superficial, la qual cosa els proporciona característiques úniques dintre dels materials sòlids. Aquest treball descriu la síntesi de nous aerogels de sílice combinat amb molècules orgàniques i les propietats noves obtingudes

Enhanced stability of superparamagnetic iron oxide nanoparticles in biological media using a pH adjusted-BSA adsorption protocol

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used for biological applications due to their unique properties compared to their bulk counterparts, simplified SPIONs stabilization protocols applicable for a wide spectra of biological media remains a challenging issue. In this work, SPIONs with different surface coatings, tetramethylammonium hydroxide-coated SPIONs (T-SPIONs), and citrate-coated SPIONs (C-SPIONs) were synthesized by a facile, rapid and cost effective microwave-assisted method. C-SPIONs show robust stability in biological media of phosphate buffered saline and Roswell Park Memorial Institute Medium, while destabilize in DMEM. T-SPIONs were found to aggregate rapidly and significantly in all tested media. Then, a modified pH adjusted-BSA adsorption protocol and an addition of excess trisodium citrate dihydrate (Na3Cit) were used to enhance their stability in the media. The BSA adsorption protocol showed great efficiency in stabilizing the dispersed state of both SPIONs in the tested media, while the addition of excess Na3Cit showed limited effect, and it was only applicable for C-SPIONs. The formed BSA layer on SPIONs could be imaged by negative staining TEM, and revealed by Cryo-TEM, FTIR, DLS, and the zeta potential measurements. Results indicated that BSA forms a monolayer of a thickness of about 3 ± 1 nm and BSA interacts with C-SPIONs and T-SPIONs through their coating, rather than by replacing them. This synthetic method and stabilization protocol offer a general methodology to obtain SPIONs with a variety of surfactants, stable in different biological media in few minutes. © 2014 Springer Science+Business Media.Acknowledgments The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement n8 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324, COST Action MP1202 and Ramon y Cajal grant RYC-2010-06082 (AL), China Scholarship Council fellowship (SMY, 201206150053).Peer Reviewe

Bacterial cellulose films: influence of bacterial strain and drying route on film properties

© 2014, Springer Science+Business Media Dordrecht. Structural properties of bacterial cellulose (BC) depend on the microstructure of the material, which in turn is influenced by the bacterial strain. This paper reports the production of BC thin films from two bacterial strains, gluconacetobacter xylinus (GX) and gluconacetobacter europaeus (GE), and three methods of drying the films; at room temperature, freeze drying and supercritical drying. The porosity, transparency, water absorption capacity (WAC) and mechanical properties of the obtained films are further investigated. We conclude that materials with different properties can be fabricated by selecting the bacterial strain or the drying method. Supercritical drying of films of GE achieved mechanically robust and extremely light films, 0.05 g/mL, with up to 96 % of porosity, and with a WAC up 110 times their dried weight. We determined that materials resulting from GE strain are not much affected by the drying method. On the other hand, GX produced BC films more sensitive to the drying method used. Films are denser, 0.6–0.2 g/mL, with tunable porosity from 60 to 90 % and their maximum WAC is 66 times their dried weight.The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement no 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324, from the Generalitat de Catalunya 2014SGR213, COST Action MP1202, Ramon y Cajal grant RYC-2010-06082 (AL), and Chinese Scholarship Council fellowship (MZ). The group of Dr. Alex Peralvarez for their help in the bacterial culture, Dr. Josep PuigMartı´ and the group of Prof. David Amabilino for the use of the optical microscope, Prof. Elies Molins and Toni Pons for the use and training in the use of the freeze drier and Dr. Roberto L. Guzman de Villoria for his advices in the mechanical measurements.Peer Reviewe

MRI/Photoluminescence Dual-Modal Imaging Magnetic PLGA Nanocapsules for Theranostics

Developing multifunctional and biocompatible drug delivery nanoplatforms that integrate high drug loads and multiple imaging modalities avoiding cross-interferences is extremely challenging. Here we report on the successful chemical reaction of the high quantum yield biodegradable and photoluminescent polyester (BPLP) with the poly(lactic-co-glycolic acid) (PLGA) polymer to fabricate biocompatible photoluminescent nanocapsules (NCs). Furthermore, we transform the PLGA-BPLP NCs into a magnetic resonance (MR)/photoluminescence dual-modal imaging theranostic platform by incorporating superparamagnetic iron oxide nanoparticles (SPIONs) into the polymeric shell. In vitro phantoms confirmed the excellent MRI-r2 relaxivity values of the NCs whilst the cellular uptake of these NCs was clearly observed by fluorescence optical imaging. Besides, the NCs (mean size ~270 nm) were loaded with ~1 wt% of a model protein (BSA) and their PEGylation provided a more hydrophilic surface. The NCs show biocompatibility in vitro, as hCMEC/D3 endothelial cells viability was not affected for particle concentration up to 500 μg/mL. Interestingly, NCs decorated with SPIONs can be exploited for magnetic guiding and retention.This work was partially supported by the Spanish Ministry of Science, Innovation and Universities through the grants PCIN-2017-090, RTI2018-096273-B-I00, CTQ2017-87637-R, SAF2017-87670-R, SEV-2015-0496 and MDM-2017-0720 and by the Generalitat de Catalunya grants (2017SGR765 & 2017SGR1427). Yajie Zhang was supported by the China Scholarship Council (CSC). The Acciones Complementarias program from the Instituto de Salud Carlos III, Spain, co-financed by the European Regional Development Fund (AC17/00004 grant) as part of the MAGBBRIS project (Euronanomed III 8th joint call), and the RETICS INVICTUS RD16/0019/0021 were acknowledged. Miguel Servet program (CPII15/00003) from Fondo de Investigaciones Sanitarias-Instituto de Salud Carlos III and ERDF, supported A. Roig research contract.Peer reviewe

Protective Effects of Bovine Serum Albumin on Superparamagnetic Iron Oxide Nanoparticles Evaluated in the Nematode Caenorhabditis elegans

Nanomaterials give rise to unique biological reactivity that needs to be thoroughly investigated. The quest for enhanced magnetic nanomaterials of different shapes, magnetic properties, or surface coatings continues for applications in drug delivery, targeting therapies, biosensing, and magnetic separation. In this context, the use of simple in vivo models, such as Caenorhabditis elegans, to biologically evaluate nanoparticles is currently in increasing demand as it offers low-cost and information-rich experiments. In this work, we evaluated how surface modification (citrate- and protein-coated) of superparamagnetic iron oxide nanoparticles (C-SPIONs and BSA-SPIONs, respectively) induces changes in their toxicological profile and biodistribution using the animal model C. elegans and combining techniques from materials science and biochemistry. The acute toxicity and nanoparticle distribution were assessed in two populations of worms (adults and larvae) treated with both types of SPIONs. After 24 h treatment, nanoparticles were localized in the alimentary system of C. elegans; acute toxicity was stronger in adults and larvae exposed to C-SPIONs rather than BSA-SPIONs. Adult uptake was similar for both SPION types, whereas uptake in larvae was dependent on the surface coating, being higher for BSA-SPIONs. Nanoparticle size was evaluated upon excretion, and a slight size decrease was found. Interestingly, all results indicate the protective effects of the BSA to prevent degradation of the nanoparticles and decrease acute toxicity to the worms, especially at high concentrations. We argue that this relevant information on the chemistry and toxicity of SPIONs in vivo could not be gathered using more classical in vitro approaches such as cell culture assays, thus endorsing the potential of C. elegans to assess nanomaterials at early stages of their synthetic formulations.C. elegans N2 and E. coli OP50 were provided by the CGC, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440). The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement nº 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324 and FEDER funds, the Generalitat de Catalunya 2014SGR213, the COST Action MP1202, Ramon y Cajal grant RYC-2010-06082 (AL), China Scholarship Council fellowship (SMY, 201206150053), and FPU fellowship FPU12/05549 (LGM).Peer Reviewe

Los equipos docentes en la educación superior ¿Utopía o realidad?

Resumen: La organización académica de los grados universitarios, en el marco del Espacio Europeo de Educación Superior, ha facilitado la constitución de equipos docentes (Zabalza, 2009; López, 2007). Este es uno de los puntos clave en los procesos de organización y mejora (Lester y Evans, 2009; Bacharach, Washut y Dahlberg, 2008) de la enseñanza universitaria, pero a la vez, un tema pendiente por la dificultad en conseguir un cambio de cultura del profesorado, enmarcado a su vez en estructuras poco ágiles y flexibles. El artículo explica una investigación realizada a un grupo de profesores universitarios, con el objetivo de realizar un diagnóstico de la situación de los equipos docentes entre los cursos 2009-2010 al 2011-2012. La metodología usada fue la encuesta, utilizando el cuestionario y el focus group como técnicas de obtención de información. Los resultados muestran que la organización en equipos docentes es una realidad percibida positivamente por el profesorado aunque con problemas y retos que indican el camino que queda aún por recorrer. Summary The academic organization of university degrees, in the frame of the European Higher Education Area, has facilitated the constitution of teachers' teams (Zabalza, 2009; Lopez, 2007). This is one of the key points in the processes of organization and improvement (Lester and Evans, 2009; Bacharach, Washut and Dahlberg, 2008) of higher education, but simultaneously, a hanging topic for the difficulty in obtaining a culture's change of university teachers, also demarcated in slightly agile and flexible structures. The paper is focused in a research caught out a group of university teachers, with the aim to realize a diagnosis of the situation of the teachers' teams between the courses 2009-2010 to 2011-2012. The methodology used was the survey, with questionnaire and focus group. The results show that the organization in teachers teams is a reality perceived positively by teachers, but with problems and challenges that we have still further to go

Material compuesto que comprende una matriz porosa de carbón amorfo y nanopartículas de Bi obtenible mediante un procedimiento sol-gel, procedimiento de obtención y su uso.

La presente invención se refiere a un material compuesto que comprende una matriz porosa de carbono amorfo con un tamaño de poro comprendido entre 2 y 1000 nm, en la que se encuentran embebidas y distribuidas homogéneamente nanopartículas esféricas de tamaño comprendido entre 5 y 500 nm de al menos un elemento metálico que es Bi en fase cristalina tetragonal, obtenible mediante un procedimiento que comprende al menos las siguientes etapas:a) preparar una composición líquida sol-gel en forma de solución que contiene al menos un precursor orgánico de la matriz en un solvente; b) depositar la solución líquida dentro de un molde o sobre un soporte en forma de capa o microestructura; c) condensar la solución líquida que contiene el precursor orgánico en el molde o en el soporte, hasta dar lugar a un gel orgánico húmedo;d) secar el gel húmedo; y e) someter el gel a pirólisis, en atmósfera inerte a una temperatura igual o superior a 800°C; donde al menos un precursor del Bi se adiciona en la primera etapa a) disolviéndose en el solvente junto al precursor orgánico para formar parte de la composición sol-gel, o se adiciona en la tercera etapa c) impregnando el gel orgánico húmedo con una solución del precursor de Bi en un solvente antes del secado; y donde el material presenta un área superficial de Bi comprendida entre 2.5-102 cm2 /g y 2.5-10 5 cm2 /g, la matriz presenta una porosidad intrínseca accesible comprendida entre 10% y 95% respecto al carbono amorfo no poroso.Peer reviewedConsejo Superior de Investigaciones CientíficasA1 Solicitud de patente con informe sobre el estado de la técnic

Epitaxial stabilization of ε-Fe2O3 (00l) thin films on SrTiO3 (111)

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.Thin films of the metastable and elusive ε-Fe2O3 have been epitaxially stabilized on SrTiO3 (111) substrates. The ε-Fe2O3 films present a (001) orientation perpendicular to the substrate and three in-plane domains measuring a few nanometers and showing atomically sharp interfaces. We argue that this domain structure, rather than the epitaxial-strain, plays an essential role in stabilizing the ε-Fe2O3 by minimizing the energy of (100) surfaces. The ε-Fe2O3 films show a large in-plane coercivity ∼ 8 kOe which combined with the magnetoelectric character claimed for this oxide may lead to novel applications in spintronics

Electrochemically Active Thin Carbon Films with Enhanced Adhesion to Silicon Substrates

Thin carbon films deposited on technologically relevant substrates, such as silicon wafers, can be easily implemented in miniaturized electrochemical devices and used for sensing applications. However, a major issue in most carbon films is the weak film/substrate adhesion that shortens the working device lifetime. This paper describes the facile preparation of robust thin carbon films on silicon substrates by one-pot sol-gel synthesis. The improved adherence of these carbon films is based on the incorporation of silica through the controlled synthesis of a resorcinol/formaldehyde gel modified with aminopropyltriethoxysilane. The films demonstrate excellent adhesion to the silicon substrate, good homogeneity, excellent electrical conductivity and superior electrochemical performance. Moreover, this approach opens the door to the fabrication of carbon thin-film electrodes by photolithographic techniques.G. Antorrena from the Laboratorio de Microscopias Avanzadas of the Instituto de Nanociencia de Aragón is acknowledged for performing XPS analysis. This research was partially funded by, the European Union’s 7th Framework Programme (FP7/2007-2013) under grant agreement number 614155, the Spanish Ministry of Economy and Competitiveness in cofounding with the European Social Funds through the MAT2012-35324 project, the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV- 2015-0496) and the Generalitat de Catalunya (2014SGR213, 2014SGR1645). The Chinese Scholarship Council fellowship (201206240033) to P.N. and the COST Action MP1202 are also acknowledged.Peer Reviewe

Explaining low farm-gate prices in the Catalan wine sector

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