Congratulations to Martí Gich, tenured researcher at the N&N group, and the rest of the authors for the recently published paper: Electric and Mechanical Switching of Ferroelectric and Resistive States in Semiconducting BaTiO3–δ Films on Silicon. Moreover, the paper was on the cover of the journal Small (Volume 13, Issue 39, October 18, 2017).
Abstract:
In article number 1701614, Andrés Gómez, Adrián Carretero-Genevrier, and co-workers report a novel approach to integrate epitaxial nanostructured n-type semiconducting BaTiO3−δ films on silicon by combining molecular beam epitaxy and a water-based chemical method. This growth strategy results into epitaxial BaTiO3−δ/La0.7Sr0.3MnO3/SrTiO3/Si columnar nanostructures that enhance the flexoelectric response of the system and enables the control of the ferroelectric polarization and local conductivity (resistive switching) of this functional oxide upon applying a mechanical load.
Here you can read the abstract of the paper:
We present a mechanistic study of the effect of iron oxide nanoparticles (SPIONs) in C. elegans combining a genome-wide analysis with the investigation of specific molecular markers frequently linked to nanotoxicity. The effects of two different coatings were explored: citrate, an anionic stabilizer, and bovine serum albumin, as a pre-formed protein corona. The transcriptomic study identified differentially expressed genes following an exposure to SPIONs. The expression of genes involved in oxidative stress, metal detoxification response, endocytosis, intestinal integrity and iron homeostasis was quantitatively evaluated. The role of oxidative stress was confirmed by gene expression analysis and by synchrotron Fourier Transform infrared microscopy based on the higher tissue oxidation of NP-treated animals. The observed transcriptional modulation of key signaling pathways such as MAPK and Wnt suggests that SPIONs might be endocytosed by clathrin-mediated processes, a putative mechanism of nanotoxicity which deserves further mechanistic investigations.
Citation: Toxicogenomics of iron oxide nanoparticles in the nematode C. elegans Laura Gonzalez-Moragas, Si-Ming Yu, Núria Benseny-Cases, Stephen Stürzenbaum, Anna Roig and Anna Laromaine Nanotoxicology, Accepted manuscript online: 15 Jun 2017. DOI: 10.1080/17435390.2017.1342011
Abstract: Understanding the in vivo fate and transport of nanoparticles (NPs) is challenging, but critical. We review recent studies of metal and metal oxide NPs using the model organism Caenorhabditis elegans, summarizing major findings to date. In a joint transdisciplinary effort, we highlight underutilized opportunities offered by powerful techniques lying at the intersection of mechanistic toxicology and materials science. To this end, we firstly summarize the influence of exposure conditions (media, duration, C. elegans lifestage) and NP physicochemical properties (size, coating, composition) on the response of the worm to NP treatment.
Next, we focus on the techniques employed to study NP entrance route, uptake, biodistribution and fate, emphasizing the potential of extending the toolkit available with novel and powerful techniques. Next, we review findings on several NP-induced biological responses, namely transport routes and altered molecular pathways, and illustrate the molecular biology and genetic strategies applied, critically reviewing their strengths and weaknesses.
Finally, we advocate the incorporation of a set of minimal materials and toxicological science experiments that will permit meta-analysis and synthesis of multiple studies in the future. We believe this review will facilitate coordinated integration of both well-established and underutilized approaches in mechanistic toxicology and materials science by the nanomaterials research community
Citation: L. Gonzalez-Moragas, L. L. Maurer, V. M. Harms, J. Meyer, A. Laromaine and A. Roig, Mater. Horiz., 2017, DOI: 10.1039/C7MH00166E
This paper is the result of a collaboration with theInstituto de Física La Plata (IFLP- CONICET) at the Universidad Nacional de La Plata (UNLP) in Argentina.
Congratulations!
Abstract:
Magnetic hyperthermia, a modality that uses radio frequency heating assisted with single-domain magnetic nanoparticles, is becoming established as a powerful oncological therapy. Much improvement in nanomateriales development, to enhance their heating efficiency by tuning the magnetic colloids properties, has been achieved.
However, methodological standardization to accurately and univocally determine the colloids properties required to numerically reproduce specific heating efficiency using analytical expressions still holds.Thus, anticipating the hyperthermic performances of magnetic colloids entails high complexity due to polydispersity, aggregation and dipolar interaction always present in real materials to a more or lesser degree.
Here, by numerically simulating experimental results and using real biomedical aqueous colloids, we analyse and compared several approaches to reproduce experimental specific absorption rate values. Then, we show that relaxation time, determined using a representative mean activation energy consistently derived from four independent experiments accurately reproduces experimental heating efficiencies.
Moreover, the so-derived relaxation time can be used to extrapolate the heating performance of the magnetic nanoparticles to other field conditions within the framework of the linear response theory. We thus present a practical tool that may truly aid the design of medical decisions.
Gold nanoparticles (AuNPs) are present in many man-made products and cosmetics, and are also used by the food and medical industries. Tight regulations regarding the use of mammalian animals for product testing can hamper the study of the specific interactions between engineered nanoparticles and biological systems. Invertebrate models, such as the nematode Caenorhabditis elegans (C. elegans), can offer alternative approaches during the early phases of nanoparticle discovery.
Panels B and C are optical microscopy images of B) 11-nm and C) 150-nm AuNPs treated worms. 11-nm AuNPs appear pink, and 150-nm AuNPs appear blue.
Here, we thoroughly evaluated the biodistribution of 11-nm and 150-nm citrate-capped AuNPs in the model organism C. elegans at multiple scales, moving from micrometric to nanometric resolution and from the organism to cellular level. We confirmed that the nanoparticles were not able to cross the intestinal and dermal barriers. We investigated the effect of AuNPs on the survival and reproductive performance of C. elegans, and correlated these effects with the uptake of AuNPs in terms of their number, surface area, and metal mass. In general, exposure to 11-nm AuNPs resulted in a higher toxicity than the larger 150-nm AuNPs. NP aggregation inside C. elegans was determined using absorbance microspectroscopy, which allowed the plasmonic properties of AuNPs to be correlated with their confinement inside the intestinal lumen, where anatomical traits, acidic pH and the presence of biomolecules play an essential role on NP aggregation. Finally, quantitative PCR of selected molecular markers indicated that exposure to AuNPs did not significantly affect endocytosis and intestinal barrier integrity.
The article reports the synthesis and catalytic performance of hybrid materials formed by a molecular ruthenium aqua complex anchored onto silica mesoporous and silica coated magnetic particles. The catalytic results and the reutilization of these hybrid materials highlight their performance in the epoxidation of alkenes.
Abstract
The preparation and characterization of new complexes with a phosphonated trpy ligand (trpy-P-Et) and a bidentate pyridylpyrazole (pypz-Me) ligand, with formula [RuII(trpy-P-Et)(pypz-Me)X]n+ (X = Cl, n= 1, 2; X=H2O, n=2, 3) is described, together with the anchoring of 3 onto two types of supports: mesoporous silica particles (SP) and silica coated magnetic particles (MSP). The aqua complex 3 is easily obtained through reflux of 2 in water and displays a bielectronic Ru(IV/II) redox process. It has been anchored onto SP and MSP supports through two different synthetic strategies, yielding the heterogeneous systems SP@3 and MSP@3 that have been fully characterized by IR, UV-vis, SEM, CV and DPV. Catalytic olefin epoxidation has been tested with the molecular complex 3 and the SP@3 and MSP@3 heterogeneous counterparts, including the reuse of the heterogeneous systems. The MSP@3 material can be easily recovered by a magnet facilitating their reusability.
This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol.
However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr2+act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.
