Institute Nanociencia Of Aragon

Zaragoza, Spain

Institute Nanociencia Of Aragon

Zaragoza, Spain
Time filter
Source Type

Serrano J.L.,University of Zaragoza | Serrano J.L.,Institute Nanociencia Of Aragon
Macromolecular Chemistry and Physics | Year: 2012

The synthesis and characterization of ionic liquid crystalline dendritic polymers based on the ammonium salts of commercially available poly(propylene imine) (PPI), poly(amidoamine) (PAMAM), poly(ethyleneimine) (PEI), and the fully methylated PEI (PEIMe) with 5-(4-cyanobiphenoxy)pentanoic acid (CBPA) are reported. The occurrence of proton transfer from the carboxylic acid to the amine groups is confirmed using IR and NMR techniques. The mesomorphic behavior is investigated by means of differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry. Although CBPA exhibits monotropic nematic mesomorphism, all ionic complexes display enantiotropic liquid crystal properties. The relationship between the mesomorphism of the complexes and their structure is discussed. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carmona D.,Institute Nanociencia Of Aragon | Carmona D.,International Iberian Nanotechnology Laboratory | Balas F.,Institute Nanociencia Of Aragon | Mayoral A.,Institute Nanociencia Of Aragon | And 3 more authors.
Chemical Communications | Year: 2011

The structure of ordered mesoporous materials presenting a cubic structure undergoes a strong modification after adding aluminium alkoxides to the synthesis gel. As a result, an outstanding increase in the surface area and pore volume is observed, together with changes in the mesopore ordering. Hydrated aluminium species influence the chemical environment of the micelles during synthesis, which seems to induce the accumulation of stacking faults in the mesopore framework, and give rise to closer structural packing. The adsorption and release of ibuprofen as a test molecule correlates well with the textural changes observed. © 2011 The Royal Society of Chemistry.

Sebastian N.,University of the Basque Country | Gimeno N.,University of Zaragoza | Vergara J.,University of Zaragoza | Lopez D.O.,Polytechnic University of Catalonia | And 4 more authors.
Journal of Materials Chemistry C | Year: 2014

The synthesis and characterization of three bent-rod dimers are reported. Very long flexible spacers that include methylene units and either a phenyl ring or a triazole moiety as connecting structures join the bent- and rod-promesogenic cores. Polarizing microscopy, modulated differential scanning calorimetry, X-ray diffraction at variable temperature and dielectric measurements have been performed to establish the mesophase behaviour of the dimers. The results show a complex supramolecular organization for this kind of flexible dimer in the mesophase. Interestingly, the length and the chemical nature of the flexible linking spacers condition the liquid crystalline properties of these novel compounds. Additionally, it has been found that the chemical structure of the rod-like core plays a key role in determining the kind of mesophase, either nematic or lamellar, formed by these materials. © 2014 the Partner Organisations.

De Miguel D.,University of Zaragoza | Gallego-Lleyda A.,University of Zaragoza | Anel A.,University of Zaragoza | Martinez-Lostao L.,University of Zaragoza | Martinez-Lostao L.,Institute Nanociencia Of Aragon
Leukemia Research | Year: 2015

Human Apo2-Ligand/TRAIL is a promising antitumor agent. Our group demonstrated that TRAIL was physiologically released to the extracellular medium inserted in lipid vesicles, known as exosomes. Recently we demonstrated that artificial lipid nanoparticles coated with bioactive TRAIL (LUV-TRAIL), which resemble the natural exosomes, greatly improved TRAIL activity compared with the soluble form of this death ligand and were able to induce apoptosis in hematological malignancies. In this study we have deepened the underlying mechanism of action of LUV-TRAIL in hematologic cells. Using histiocytic lymphoma U937 cells, we demonstrated that TRAIL signaling almost exclusively depends on DR5 despite these cells expressing high amounts of DR4, and proved that LUV-TRAIL's higher pro-apoptotic effect relies on its superior ability to induce DR5 clustering on cell surface, therefore enhancing DISC recruitment and triggering caspase activation more efficiently than the soluble form of TRAIL. © 2015 Elsevier Ltd.

Roca A.G.,Institute Nanociencia Of Aragon | Roca A.G.,CIBER ISCIII | Roca A.G.,University of Zaragoza | Carmona D.,Institute Nanociencia Of Aragon | And 10 more authors.
Nanotechnology | Year: 2012

We report here a detailed structural and magnetic study of different silica nanocapsules containing uniform and highly crystalline maghemite nanoparticles. The magnetic phase consists of 5nm triethylene glycol (TREG)- or dimercaptosuccinic acid (DMSA)-coated maghemite particles. TREG-coated nanoparticles were synthesized by thermal decomposition. In a second step, TREG ligands were exchanged by DMSA. After the ligand exchange, the ζ potential of the particles changed from 10 to 40mV, whereas the hydrodynamic size remained constant at around 15nm. Particles coated by TREG and DMSA were encapsulated in silica following a solgel procedure. The encapsulation of TREG-coated nanoparticles led to large magnetic aggregates, which were embedded in coalesced silica structures. However, DMSA-coated nanoparticles led to small magnetic clusters inserted in silica spheres of around 100nm. The final nanostructures can be described as the result of several competing factors at play. Magnetic measurements indicate that in the TREG-coated nanoparticles the interparticle magnetic interaction scenario has not dramatically changed after the silica encapsulation, whereas in the DMSA-coated nanoparticles, the magnetic interactions were screened due to the function of the silica template. Moreover, the analysis of the AC susceptibility suggests that our systems essentially behave as cluster spin glass systems. © 2012 IOP Publishing Ltd.

Hernandez-Ainsa S.,University of Zaragoza | Barbera J.,University of Zaragoza | Marcos M.,University of Zaragoza | Serrano J.L.,Institute Nanociencia Of Aragon
Macromolecules | Year: 2012

Two novel series of dendrimers constituted by the ionic grafting of poly(propyleneimine) PPI-(NH 2) x (x = 4, 8, 16, 32, 64) and poly(amidoamine) PAMAM-(NH 2) x (x = 64) with carboxylic acids bearing an oxadiazole ring have been synthesized, and their liquid crystalline properties have been investigated. Series I is generated by the ionic attachment between the dendrimers and 1,3,4-oxadiazole-containing acids. Series II results from the ionic junction of the dendrimers to 1,2,4-oxadiazole-containing acids. The liquid crystalline behavior has been investigated by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffractometry (XRD). The liquid crystal properties are significantly improved in the dendrimers compared to the mesogenic precursors. The structural parameters determined by X-ray diffraction reflect the different supramolecular organization built by each kind of oxadiazole-containing acid introduced. On the basis of these experimental results, a packing model is proposed based on a microsegregation phenomenon and a variable degree of interdigitation between the mesogenic units. The absorption and emission properties of the compounds have also been studied. To our knowledge, these are the first dendrimers reported up to date combining oxadiazole units and liquid crystal properties. © 2011 American Chemical Society.

Susi T.,Aalto University | Kaskela A.,Aalto University | Zhu Z.,Aalto University | Ayala P.,University of Vienna | And 14 more authors.
Chemistry of Materials | Year: 2011

Nitrogen-doped single-walled carbon nanotubes (N-SWCNTs) were synthesized using a floating catalyst aerosol chemical vapor deposition method, with carbon monoxide as the carbon source, ammonia as the nitrogen source, and iron particles derived from evaporated iron as the catalyst. The material was deposited on various substrates as grown directly from the gas phase as films and subsequently characterized by Raman and optical absorption spectroscopies, sheet resistance measurements, electron microscopy, energy-loss spectroscopy, and X-ray photoelectron spectroscopy.The sheet resistance measurements revealed that the doped films had unexpectedly high resistances. This stands in contrast to the case of N-MWCNT films, where decreased resistance has been reported with N-doping. To understand this effect, we developed a resistor network model, which allowed us to disentangle the contribution of bundle-bundle contacts when combined with data on undoped films. Assuming doping does not significantly change the contacts, the increased resistances of the doped films are likely due to enhanced carrier scattering by defect sites in the nanotubes. This work represents the first experimental report on macroscopic N-SWCNT thin films. © 2011 American Chemical Society.

Asin L.,University of Zaragoza | Ibarra M.R.,University of Zaragoza | Tres A.,Hospital Universitario Lozano Blesa | Goya G.F.,University of Zaragoza | Goya G.F.,Institute Nanociencia Of Aragon
Pharmaceutical Research | Year: 2012

Purpose: To investigate the effects of alternating magnetic fields (AMF) on the death rate of dendritic cells (DCs) loaded with magnetic nanoparticles (MNPs) as heating agents. AMF exposure time and amplitude as well as the MNPs concentration were screened to assess the best conditions for a controlled field-induced cell death. Methods: Human-monocyte-derived DCs were co-incubated with dextran-coated MNPs. The cells were exposed to AMF (f=260 kHz; 0

Ranzieri P.,CNR Institute of Materials for Electronics and Magnetism | Campanini M.,CNR Institute of Materials for Electronics and Magnetism | Fabbrici S.,CNR Institute of Materials for Electronics and Magnetism | Fabbrici S.,MIST E R Laboratory | And 10 more authors.
Advanced Materials | Year: 2015

Giant magnetically induced twin variant reorientation, comparable in intensity with bulk single crystals, is obtained in epitaxial magnetic shape-memory thin films. It is found to be tunable in intensity and spatial response by the fine control of microstructural patterns at the nanoscopic and microscopic scales. A thorough experimental study (including electron holography) allows a multiscale comprehension of the phenomenon. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Susi T.,Aalto University | Kotakoski J.,University of Vienna | Kotakoski J.,University of Helsinki | Arenal R.,Institute Nanociencia Of Aragon | And 12 more authors.
ACS Nano | Year: 2012

By combining ab initio simulations with state-of-the-art electron microscopy and electron energy loss spectroscopy, we study the mechanism of electron beam damage in nitrogen-doped graphene and carbon nanotubes. Our results show that the incorporation of nitrogen atoms results in noticeable knock-on damage in these structures already at an acceleration voltage of 80 kV, at which essentially no damage is created in pristine structures at corresponding doses. Contrary to an early estimate predicting rapid destruction via sputtering of the nitrogen atoms, in the case of substitutional doping, damage is initiated by displacement of carbon atoms neighboring the nitrogen dopant, leading to the conversion of substitutional dopant sites into pyridinic ones. Although such events are relatively rare at 80 kV, they become significant at higher voltages typically used in electron energy loss spectroscopy studies. Correspondingly, we measured an energy loss spectrum time series at 100 kV that provides direct evidence for such conversions in nitrogen-doped single-walled carbon nanotubes, in excellent agreement with our theoretical prediction. Besides providing an improved understanding of the irradiation stability of these structures, we show that structural changes cannot be neglected in their characterization employing high-energy electrons. © 2012 American Chemical Society.

Loading Institute Nanociencia Of Aragon collaborators
Loading Institute Nanociencia Of Aragon collaborators