Institute Catala Of Nanotecnologia

Barcelona, Spain

Institute Catala Of Nanotecnologia

Barcelona, Spain
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Ojea-Jimenez I.,Endor | Ojea-Jimenez I.,Catalan Institute of Nanoscience and Nanotechnology | Ojea-Jimenez I.,Institute Catala Of Nanotecnologia | Romero F.M.,University of Valencia | And 7 more authors.
Journal of Physical Chemistry C | Year: 2010

The effect of solvent isotopic replacement (H for D) on the size of gold nanoparticles (Au NPs) prepared by sodium citrate reduction has been investigated. With increasing replacement of water by deuterium oxide, smaller sizes of Au NPs are obtained, which is interpreted as a consequence of a faster reduction. A mechanism in which a substitution complex, [AuCl 3(C 6H 5O 7) -2] -, is formed from AuCl 4 and citrate ions prior to its rate-limiting disproportionation into products is suggested. This novel procedure offers an attractive alternative to the existing ones and opens a full range of possibilities for biological studies. © 2010 American Chemical Society.

Tavernarakis A.,ICFO - Institute of Photonic Sciences | Chaste J.,Institute Catala Of Nanotecnologia | Eichler A.,ICFO - Institute of Photonic Sciences | Eichler A.,Institute Catala Of Nanotecnologia | And 5 more authors.
Physical Review Letters | Year: 2014

We study monolayers of noble gas atoms (Xe, Kr, Ar, and Ne) deposited on individual ultraclean suspended nanotubes. For this, we record the resonance frequency of the mechanical motion of the nanotube, since it provides a direct measure of the coverage. The latter is the number of adsorbed atoms divided by the number of the carbon atoms of the suspended nanotube. Monolayers form when the temperature is lowered in a constant pressure of noble gas atoms. The coverage of Xe monolayers remains constant at 1/6 over a large temperature range. This finding reveals that Xe monolayers are solid phases with a triangular atomic arrangement, and are commensurate with the underlying carbon nanotube. By comparing our measurements to theoretical calculations, we identify the phases of Ar and Ne monolayers as fluids, and we tentatively describe Kr monolayers as solid phases. These results underscore that mechanical resonators made from single nanotubes are excellent probes for surface science. © 2014 American Physical Society.

Del Mercato L.L.,University of Marburg | Del Mercato L.L.,CNR Institute of Neuroscience | Gonzalez E.,Institute Catala Of Nanotecnologia | Gonzalez E.,Catalan Institution for Research and Advanced Studies | And 4 more authors.
Journal of Materials Chemistry | Year: 2011

The Layer-by-Layer fabrication of polyelectrolyte capsules with and without Au nanoparticles embedded into their walls is reported. We have studied the behaviour of these capsules under microwave irradiation. Their properties have been investigated by transmission electron microscopy and dynamic light scattering measurements. We demonstrate that microwaves affect the structure of both capsules types by inducing remarkable damage to the multilayer wall. We also show that upon microwave exposure the walls of polyelectrolyte capsules which are modified with Au nanoparticles undergo rapid damage compared to capsules without incorporated nanoparticles. These results indicate that microwaves can be used to control the opening of cargo-loaded capsules, which could be harnessed for drug delivery purposes. © 2011 The Royal Society of Chemistry.

Rivera Gil P.,University of Marburg | Oberdorster G.,University of Rochester | Elder A.,University of Rochester | Puntes V.,Institute Catala Of Nanotecnologia | Parak W.J.,University of Marburg
ACS Nano | Year: 2010

Nanotoxicology is still a new discipline. In this Perspective, both its origins and its future trends are discussed. In particular, we note several issues we consider important for publications in this field. © 2010 American Chemical Society.

Varon M.,Institute Catala Of Nanotecnologia | Pena L.,CSIC - Institute of Materials Science | Balcells L.,CSIC - Institute of Materials Science | Skumryev V.,Autonomous University of Barcelona | And 4 more authors.
Langmuir | Year: 2010

Superparamagnetic single crystal single domain Co nanoparticles of 6 nm in diameter evaporated onto highly pyrolytic oriented graphite spontaneously self-assemble into super structures with an elongated shape. These structures have been studied by optical and scanning electron microscopies, atomic and magnetic force microscopy, electron dispersive X-ray analysis, and SQUID magnetometry. We propose that the weak dipolar interactions between superparamagnetic dipoles of the cobalt nanoparticles are responsible for the formation of these structures when the dipolar magnetic interactions are strong enough to influence the general process of self-assembly dominated by van der Waals forces between neighboring nanoparticles and between nanoparticles and the substrate during evaporation of the solvent. © 2009 American Chemical Society.

Goy-Lopez S.,University of Santiago de Compostela | Juarez J.,University of Santiago de Compostela | Alatorre-Meda M.,University of Santiago de Compostela | Casals E.,Institute Catala Of Nanotecnologia | And 4 more authors.
Langmuir | Year: 2012

Gold nanoparticles (Au NPs) from 5 to 100 nm in size synthesized with HAuCl 4 and sodium citrate were complexed with the plasma protein human serum albumin (HSA). Size, surface charge, and surface plasmon bands of the Au NPs are largely modified by the formation of a protein corona via electrostatic interactions and hydrogen bonding as revealed by thermodynamic data. Negative values of the entropy of binding suggested a restriction in the biomolecule mobility upon adsorption. The structure of the adsorbed protein molecules is slightly affected by the interaction with the metal surface, but this effect is enhanced as the NP curvature decreases. Also, it is observed that the protein molecules adsorbed onto the NP surface are more resistant to complete thermal denaturation than free protein ones as deduced from the increases in the melting temperature of the adsorbed protein. Differences in the conformations of the adsorbed protein molecules onto small (<40 nm) and large NPs were observed on the basis of potential data and FTIR spectroscopy, also suggesting a better resistance of adsorbed protein molecules to thermal denaturing conditions. We think this enhanced protein stability is responsible for a reduced formation of HSA amyloid-like fibrils in the presence of small Au NPs under HSA fibrillation conditions. © 2012 American Chemical Society.

Eichler A.,Institute Catala Of Nanotecnologia | Del Alamo Ruiz M.,Institute Catala Of Nanotecnologia | Plaza J.A.,IMB CNM CSIC | Bachtold A.,Institute Catala Of Nanotecnologia
Physical Review Letters | Year: 2012

We report on the nonlinear coupling between the mechanical modes of a nanotube resonator. The coupling is revealed in a pump-probe experiment where a mode driven by a pump force is shown to modify the motion of a second mode measured with a probe force. In a second series of experiments, we actuate the resonator with only one oscillating force. Mechanical resonances feature exotic line shapes with reproducible dips, peaks, and jumps when the measured mode is commensurate with another mode with a frequency ratio of either 2 or 3. Conventional line shapes are recovered by detuning the frequency ratio using the voltage on a nearby gate electrode. The exotic line shapes are attributed to strong coupling between the mechanical modes. The possibility to control the strength of the coupling with the gate voltage holds promise for various experiments, such as quantum manipulation, mechanical signal processing, and the study of the quantum-to-classical transition. © 2012 American Physical Society.

Casals E.,Institute Catala Of Nanotecnologia | Pfaller T.,University of Salzburg | Duschl A.,University of Salzburg | Oostingh G.J.,University of Salzburg | And 2 more authors.
ACS Nano | Year: 2010

In this work, we explore the formation of the protein corona after exposure of metallic Au nanoparticles (NPs), with sizes ranging from 4 to 40 nm, to cell culture media containing 10% of fetal bovine serum. Under in vitro cell culture conditions, zeta potential measurements, UV - vis spectroscopy, dynamic light scattering and transmission electron microscope analysis were used to monitor the time evolution of the inorganic NP - protein corona formation and to characterize the stability of the NPs and their surface state at every stage of the experiment. As expected, the red-shift of the surface plasmon resonance peak, as well as the drop of surface charge and the increase of the hydrodynamic diameter indicated the conjugation of proteins to NPs. Remarkably, an evolution from a loosely attached toward an irreversible attached protein corona over time was observed. Mass spectrometry of the digested protein corona revealed albumin as the most abundant component which suggests an improved biocompatibility. © 2010 American Chemical Society.

Lim S.I.,Institute Catala Of Nanotecnologia | Varon M.,Institute Catala Of Nanotecnologia | Ojea-Jimenez I.,Institute Catala Of Nanotecnologia | Arbiol J.,CSIC - Institute of Materials Science | And 3 more authors.
Chemistry of Materials | Year: 2010

We have explored size- and shape-controlled synthesis of platinum nanocrystals (Pt NCs) by systematically comparing the differential reducing performance of two competing reducing agents in a one-pot synthesis: hexadecanediol, a weak reducer, and metallic cobalt or superhydride, stronger reducers of Pt. In addition to its role as a metal reducer, Co also functions as a shape-directing agent and is incorporated into the Pt NCs, forming a PtCo alloy structure. By maintaining a constant HDD concentration and systematically increasing the Co content, the shape of the resulting NCs was found to alter from polypods, when no Co was present, to cuboctahedrons and cubes when trace amounts of Co were added, and back to polypods when Co dominated the reduction process. On the other hand, when the concentration of HDD was systematically increased (with Co kept constant), evolution from polypod morphology to prismatic/spherical/cubic NCs, followed by irregular shapes was observed. Both experimental results indicate the importance of the competitive role between the reducing agents, their concentration limits for achieving a controlled morphology, and the presence of Co as a shape-directing agent to alter the NC shape. This allows the exploration of a wide range of NC morphologies without significant modification of the synthesis recipe. © 2010 American Chemical Society.

Lim S.I.,Institute Catala Of Nanotecnologia | Ojea-Jimenez I.,Institute Catala Of Nanotecnologia | Varon M.,Institute Catala Of Nanotecnologia | Casals E.,Institute Catala Of Nanotecnologia | And 4 more authors.
Nano Letters | Year: 2010

The introduction of metallic traces into the synthesis of platinum nanocrystais (Pt NCs) has been investigated as a surfactant independent means of controlling shape. Various nanocrystal morphologies have been produced without modification of the reaction conditions, composition, and concentration other than the presence of cobalt traces (<5%). In the presence of metallic cobalt (a strong reducer for Pt cations) cubic Pt NCs are obtained, while cobalt ions or gold NCs have no effect on the synthesis, and as a result, polypods are obtained. Intermediate shapes such as cemented cubes or cuboctahedron NCs are also obtained under similar conditions. Thus, various NC shapes can be obtained with subtle changes, which illustrates the high susceptibility and mutability of the NC shape to modification of the reaction kinetics during the early reduction process. Our studies help progress toward a general mechanism for nanocrystal shape control. © 2010 American Chemical Society.

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