Silica Meets Tannic Acid: Designing Green Nanoplatforms for Environment Preservation

Hybrid tannic acid-silica-based porous nanoparticles, TA-SiO(2) NPs, have been synthesized under mild conditions in the presence of green and renewable tannic acid biopolymer, a glycoside polymer of gallic acid present in a large part of plants. Tannic acid (TA) was exploited as both a structuring directing agent and green chelating site for heavy metal ions recovery from aqueous solutions. Particles morphologies and porosity were easily tuned by varying the TA initial amount. The sample produced with the largest TA amount showed a specific surface area an order of magnitude larger than silica nanoparticles. The adsorption performance was investigated by using TA-SiO(2) NPs as adsorbents for copper (II) ions from an aqueous solution. The effects of the initial Cu(2+) ions concentration and the pH values on the adsorption capability were also investigated. The resulting TA-SiO(2) NPs exhibited a different adsorption behaviour towards Cu(2+), which was demonstrated through different tests. The largest adsorption (i.e., ~50 wt% of the initial Cu(2+) amount) was obtained with the more porous nanoplatforms bearing a higher final TA content. The TA-nanoplatforms, stable in pH value around neutral conditions, can be easily produced and their use would well comply with a green strategy to reduce wastewater pollution

Effects of post cure treatment in the glass transformation range on the structure and fire behavior of in situ generated siilica/epoxy hybrids

A new "in situ” sol–gel synthesis procedure was exploited to produce silica/epoxy nanocomposites with 6 wt.% maximum silica content. 3-Aminopropyltriethoxysilane (APTS) was used as a coupling agent. The experimental results (fourier- transform infrared spectroscopy, FTIR, small-angle X-ray scattering, SAXS, transmission electron microscopy, TEM, nuclear magnetic resonance, NMR, and dynamic mechanical analysis, DMA) support that the structure consists of nanosized silica particles (maximum 1.25 nm in size) embedded in a hybrid co-continuous network. A post cure non-isothermal heating from 15 to 100 °C (beyond the Tg of the neat epoxy) caused Tg and storage modulus to increase. The fire behavior, that, owing to severe regulations (i.e., in aerospace engineering), often prevents composites applications, was also studied. The formed silica domains prevented melt dripping phenomena during vertical flame spread tests. Cone calorimetry tests showed a remarkable decrease of the heat release rate (HRR) for all the hybrid systems with respect to the neat cured resin, even at very low silica loadings (i.e., 2 wt.%). This decrease was much more pronounced for the hybrid structures that were not subjected to the post cure thermal treatment. The use of multiple structural investigation techniques allowed to choose among multiple hypothesis and conclude that nanoparticles clustering is the main reason of the effects of the post curing treatments

Aprendizajes y prácticas educativas en las actuales condiciones de época: COVID-19

“Esta obra colectiva es el resultado de una convocatoria a docentes, investigadores y profesionales del campo pedagógico a visibilizar procesos investigativos y prácticas educativas situadas en el marco de COVI-19. La misma se inscribe en el trabajo llevado a cabo por el equipo de Investigación responsable del Proyecto “Sentidos y significados acerca de aprender en las actuales condiciones de época: un estudio con docentes y estudiantes de la educación secundarias en la ciudad de Córdoba” de la Facultad de Filosofía y Humanidades. Universidad Nacional de Córdoba. El momento excepcional que estamos atravesando, pero que también nos atraviesa, ha modificado la percepción temporal a punto tal que habitamos un tiempo acelerado y angustiante que nos exige la producción de conocimiento provisorio. La presente publicación surge como un espacio para detenernos a documentar lo que nos acontece y, a su vez, como oportunidad para atesorar y resguardar las experiencias educativas que hemos construido, inventado y reinventando en este contexto. En ella encontrarán pluralidad de voces acerca de enseñar y aprender durante la pandemia. Este texto es una pausa para reflexionar sobre el hacer y las prácticas educativas por venir”.Fil: Beltramino, Lucia (comp.). Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Archivología; Argentina

Sintesi Sol-Gel e Caratterizzazione di Materiali Ibridi e Nanocompositi

Sintesi Sol-Gel e Caratterizzazione di Materiali Ibridi e Nanocomposit

In-situ sol-gel synthesis and characterization of bioactive pHEMA/SiO2 blend hybrids

A novel procedure to synthesize poly(2-hydroxyethylmethacrylate)-silica blend hybrids is presented. Methacrylate monomers bearing an alkoxysilyl unit, prepared by Michael addition of 2-hydroxyethylmethacrylate (HEMA) to 3-Aminopropyltriethoxysilane (APTS) were employed. By 13C NMR and mass analysis it was possible to establish the formation of coupling hybrid species. Hybrid materials, with final concentration ranging from 10% to 30% w/w of silica gel to the mass of polymer, were obtained through basic catalyzed sol-gel process of tetraethoxysilane (TEOS) and the alkoxysilyl unit of the hybrid monomer, followed by in-situ free-radical polymerization. The hybrids were characterized as far as concerns their thermal properties (glass transition temperature, decomposition temperature), their sorption behaviour in water, and in-vitro bioactivity. Optical transparency, higher glass transition temperature, and higher decomposition temperature than pHEMA suggest an increase in either density or intensity of cross-links between the organic and the inorganic phases. The swelling ratio of the 30% hybrids is comparable to pHEMA, whereas it is lower for the other compositions. In-vitro bioactivity of the hybrids, due to the inorganic phase, was ascertained. Soaking time required for apatite deposition on the samples surface decreases as the content of silica gel increases. Therefore, the obtained bioactive hybrids can be used to make bioactive scaffolds for bone engineering

Towards the development of a novel bioinspired functional material: Synthesis and characterization of hybrid TiO 2/DHICA-melanin nanoparticles

A large number of recent literature data focus on modification/modulation of surface chemistry of inorganic materials in order to improve their functional properties. Melanins, a wide class of natural pigments, are recently emerging as a powerful organic component for developing bioinspired active material for a large number of applications from organoelectronics to bioactive compounds. Here we report the use of the approach referred as "chimie douce", involving in situ formation of the hybrids through reactions of precursors under mild conditions, to prepare novel hybrid functional architectures based on eumelanin like 5,6 dihydroxyindole-2-carboxylic acid (DHICA) polymer and TiO 2. Two synthesis procedures were carried out to get DHICA-melanin coated TiO 2 nanoparticles as well as mixed DHICA/TiO 2 hybrid nanostructures. Such systems were characterized through EPR, FT-IR and fluorescence spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and TEM microscopy in order to assess the effect of synthesis path as well as of DHICA content on structural, morphological and optical properties of TiO 2 nanostructures. In particular, EPR, FT-IR spectra and TGA analysis confirmed the presence of DHICA-melanin in these samples. TEM measurements indicated the formation of the nanoparticles having relatively narrow size distribution with average particle size of about 10 nm. DHICA-melanin does act as a morphological agent affecting morphology of hybrid nanostructures. XRD analysis proved that TiO 2 hybrid nanoparticles kept anatase structures for DHICA-melanin contents within the range of investigated compositions, i.e. up to 50% wt/wt. © 2012 Elsevier B.V. All rights reserved

Shall We Tune? From Core-Shell to Cloud Type Nanostructures in Heparin/Silica Hybrids

Heparin plays multiple biological roles depending on the availability of active sites strongly influenced by the conformation and the structure of polysaccharide chains. Combining different components at the molecular scale offers an extraordinary chance to easily tune the structural organization of heparin required for exploring new potential applications. In fact, the combination of different material types leads to challenges that cannot be achieved by each single component. In this study, hybrid heparin/silica nanoparticles were synthesized, and the role of silica as a templating agent for heparin supramolecular organization was investigated. The effect of synthesis parameters on particles compositions was deeply investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Transmission Electron Microscopy (TEM) reveals a different supramolecular organization of both components, leading to amazing organic-inorganic nanoparticles with different behavior in drug encapsulation and release. Furthermore, favorable biocompatibility for healthy human dermal fibroblasts (HDF) and tumor HS578T cells has been assessed, and a different biological behavior was observed, ascribed to different surface charge and morphology of synthesized nanoparticles