Hot off the press: published paper on Nanoscale!

The paper entitled “Nanoclusters of crystallographically aligned nanoparticles for magnetic thermotherapy: aqueous ferrofluid, agarose phantoms and ex vivo melanoma tumour assessment” has recently been published on the Nanoscale Journal. We congratulate Anna Roig and our collaborator Marcela Fernández for being authors of this nice study!

 

Abstract: Magnetic hyperthermia is an oncological therapy where magnetic nanostructures, under a radiofrequency field, act as heat transducers increasing tumour temperature and killing cancerous cells. Nanostructure heating efficiency depends both on the field conditions and on the nanostructure properties and mobility inside the tumour. Such nanostructures are often incorrectly bench-marketed in the colloidal state and using field settings far off from the recommended therapeutic values. Here, we prepared nanoclusters composed of iron oxide magnetite nanoparticles crystallographically aligned and their specific absorption rate (SAR) values were calorimetrically determined in physiological fluids, agarose-gel-phantoms and ex vivo tumours extracted from mice challenged with B16-F0 melanoma cells. A portable, multipurpose applicator using medical field settings; 100 kHz and 9.3 kA m−1, was developed and the results were fully analysed in terms of nanoclusters’ structural and magnetic properties. A careful evaluation of the nanoclusters’ heating capacity in the three milieus clearly indicates that the SAR values of fluid suspensions or agarose-gel-phantoms are not adequate to predict the real tissue temperature increase or the dosage needed to heat a tumour. Our results show that besides nanostructure mobility, perfusion and local thermoregulation, the nanostructure distribution inside the tumour plays a key role in effective heating. A suppression of the magnetic material effective heating efficiency appears in tumour tissue. In fact, dosage had to be increased considerably, from the SAR values predicted from fluid or agarose, to achieve the desired temperature increase. These results represent an important contribution towards the design of more efficient nanostructures and towards the clinical translation of hyperthermia.

Hot off the press: Published paper in Nature Communications!

We are happy to announce that last 1st of November 2018, the paper “Stability and nature of the volume collapse of ε-Fe2O3 under extreme conditions” was published on the journal Nature Communications. This study is co-authored by the permanent researcher at the N&N group Martí Gich.

 

Abstract: Iron oxides are among the major constituents of the deep Earth’s interior. Among them, the epsilon phase of Fe2O3 is one of the less studied polymorphs and there is a lack of information about its structural, electronic and magnetic transformations at extreme conditions. Here we report the precise determination of its equation of state and a deep analysis of the evolution of the polyhedral units under compression, thanks to the agreement between our experiments and ab-initio simulations. Our results indicate that this material, with remarkable magnetic properties, is stable at pressures up to 27 GPa. Above 27 GPa, a volume collapse has been observed and ascribed to a change of the local environment of the tetrahedrally coordinated iron towards an octahedral coordination, finding evidence for a different iron oxide polymorph. DOI: https://doi.org/10.1038/s41467-018-06966-9

 

Congratulations Martí!

Hot off the press! Published paper on The Chemical Record

Congratulations to the authors Martí Gich, Anna Roig (N&N group), Pengfei Niu (former member of the N&N group) and César Fernández‐Sánchez (N&N collaborator form the Barcelona Institute of Microelectronics) for their published paper “Metal Nanoparticle Carbon Gel Composites in Environment in Water Sensing Applications”. The manuscript was published in the journal Chemical Record in a special issue dedicated to Prof. Ruiz-Hitzky.

 

Abstract: The synthesis of organic‐inorganic nanocomposites that can interact with different environmental pollutants and can be mass‐produced are very promising materials for the fabrication of chemical sensor devices. Among them, metal (or metal oxide) nanoparticles doped conductive porous carbon composites can be readily applied to the production of electrochemical sensors and show enhanced sensitivity for the measurement of water pollutants, thanks to the abundant accessible and functional sites provided by the interconnected porosity and the metallic nanoparticles, respectively. In this personal account, an overview of several synthesis routes of porous carbon composites containing metallic nanoparticles is given, paying special attention to those based on sol‐gel techniques. These are very powerful to synthesize hybrid porous materials that can be easily processed into powders and thin films, so that they can be implemented in electrode fabrication processes based on screen‐printing and lithography techniques, respectively. We emphasize the sol‐gel routes developed in our group for the synthesis of bismuth or gold nanoparticle doped porous carbon composites applied to fabricate electrochemical sensors that can be scaled down to produce miniaturized on‐chip sensing devices for the sensitive detection of heavy metal pollutants in water. The trend towards the miniaturization of electrochemical sensors to be readily employed as analytical tools in environmental monitoring follow the market requirements of rapid and accurate on‐site analysis, small sample consumption and waste production, as well as potential for continuous or semi‐continuous in‐situ determination of a wide variety of target analytes.

New paper from the group!

Congratulations to Anna LaromaineAnna Roig and their collaborators from the Karlsruhe Institute of Technology Tina Tronser (first author) and Pavel A. Levkin for their new paper: Bacterial Cellulose Promotes Long-Term Stemness of mESC! This manuscript was published on ACS Applied Materials and Interfaces the 20th of April 2018.  

 

Abstract: Stem cells possess unique properties, such as the ability to self-renew and the potential to differentiate into an organism’s various cell types. These make them highly valuable in regenerative medicine and tissue engineering. Their properties are precisely regulated in vivo through complex mechanisms that include multiple cues arising from the cell interaction with the surrounding extracellular matrix, neighboring cells, and soluble factors. Although much research effort has focused on developing systems and materials that mimic this complex microenvironment, the controlled regulation of differentiation and maintenance of stemness in vitro remains elusive. In this work, we demonstrate, for the first time, that the nanofibrous bacterial cellulose (BC) membrane derived from Komagataeibacter xylinus can inhibit the differentiation of mouse embryonic stem cells (mESC) under long-term conditions (17 days), improving their mouse embryonic fibroblast (MEF)-free cultivation in comparison to the MEF-supported conventional culture. The maintained cells’ pluripotency was confirmed by the mESCs’ ability to differentiate into the three germ layers (endo-, meso-, and ectoderm) after having been cultured on the BC membrane for 6 days. In addition, the culturing of mESCs on flexible, free-standing BC membranes enables the quick and facile manipulation and transfer of stem cells between culture dishes, both of which significantly facilitate the use of stem cells in routine culture and various applications. To investigate the influence of the structural and topographical properties of the cellulose on stem cell differentiation, we used the cellulose membranes differing in membrane thickness, porosity, and surface roughness. This work identifies bacterial cellulose as a novel convenient and flexible membrane material enabling long-term maintenance of mESCs’ stemness and significantly facilitating the handling and culturing of stem cells.

 

Hot of the press! New article about Bacterial Cellulose

Congratulations to the authors: Anna Laromaine, Tina Tronser, Ivana Pini, Sebastià Parets, Pavel A. Levkin and Anna Roig for their new publication on Soft Matter. The paper entitled “Free-standing three-dimensional hollow bacterial cellulose structures with controlled geometry via patterned superhydrophobic–hydrophilic surfaces” was published on the 17th of April 2018. 

Abstract
Bacteria can produce cellulose, one of the most abundant biopolymer on earth, and it emerges as an interesting candidate to fabricate advanced materials. Cellulose produced by Komagataeibacter Xylinus a bacterial strain, is a pure water insoluble biopolymer, without hemicelluloses or lignin. Bacterial cellulose (BC) exhibits a nanofibrous porous network microstructure with high strength, low density and high biocompatibility and it has been proposed as a cell scaffold and wound healing material. The formation of three dimensional (3D) cellulose self-standing structures is not simple. It either involves complex multi-step synthetic procedures or uses chemical methods to dissolve the cellulose and remold it. Here we present an in situ single-step method to produce self-standing 3D-BC structures with controllable wall thickness, size and geometry in a reproducible manner. Parameters such as hydrophobicity of the surfaces, volume of the inoculum and time of culture define the resulting 3D-BC structures. Hollow spheres and convex domes can be easily obtained by changing the surface wettability where the BC grows. The potential of these structures as a 3D cell scaffold is exemplified supporting the growth of mouse embryonic stem cells within a hollow spherical BC structure, indicating its biocompatibility and future prospective.

Hot off the press: First paper from Miquel and Pol!

Schematic representation of the two-step microwave-assisted synthesis of Au/TiO2 nanostructures.

New publication from the N&N group in collaboration with the Universitat Politècnica de Catalunya!

 

Congratulations to all the authors of the manuscript and especially to Miquel Torras (Ph.D. student at the N&N group) and Pol Sallés (previous researcher at the N&N group) for the first publication of their careers! The paper “Fast and Simple Microwave Synthesis of TiO2/Au Nanoparticles for Gas-Phase Photocatalytic Hydrogen Generation” has been published on April 12th 2018 at the open access journal Frontiers in Chemistry.

 

Abstract: The fabrication of small anatase titanium dioxide (TiO2) nanoparticles (NPs) attached to larger anisotropic gold (Au) morphologies by a very fast and simple two-step microwave-assisted synthesis is presented. The TiO2/Au NPs are synthesized using polyvinylpyrrolidone (PVP) as reducing, capping and stabilizing agent through a polyol approach. To optimize the contact between the titania and the gold and facilitate electron transfer, the PVP is removed by calcination at mild temperatures. The nanocatalysts activity is then evaluated in the photocatalytic production of hydrogen from water/ethanol mixtures in gas-phase at ambient temperature. A maximum value of 5.3 mmol·g−1cat⋅gcat-1·h−1 (7.4 mmol·g−1TiO2⋅gTiO2-1·h−1) of hydrogen is recorded for the system with larger gold particles at an optimum calcination temperature of 450°C. Herein we demonstrate that TiO2-based photocatalysts with high Au loading and large Au particle size (≈50 nm) NPs have photocatalytic activity.

Hot off the press: paper about magnetic wood

Congratulations to the authors: Jana S. Segmehl, Anna Laromaine, Tobias Keplinger, Anna May-Masnou, Ingo Burgertab and Anna Roig for their new publication entitled: Magnetic wood by in situ synthesis of iron oxide nanoparticles via a microwave-assisted route. The paper was first published on 9th of March 2018 in the Journal of Materials Chemistry. 

 

Abstract:
Functional materials with high porosity and hierarchical structures are highly demanded for numerous material applications. In this study a magnetic hybrid material derived from wood and superparamagnetic iron oxide nanoparticles (SPIONs), was synthesized by microwave-assisted thermal decomposition. This novel in situfunctionalization approach resulted in a homogeneous distribution of the integrated inorganic component within the entire complex wood cell wall structure, which was previously not achieved. In a detailed investigation based on confocal Raman microscopy imaging, transmission electron microscopy, and optical microscopy the precipitated phase and the resulting hybrid structure were characterized. Magnetic measurements revealed the impact of the anisotropic wood scaffold on the integrated magnetic functionality and confirmed the isotropic superparamagnetic characteristics of the in situ precipitated nanoparticles. Therewith, it is clearly demonstrated, that the anisotropic properties of the obtained hybrid material result from the particle organization in the given spruce wood structure and no alteration of particle properties is induced by the presence of the lignocellulosic material.

Hot off the press: new article from the group

Hot off the press!
New article from the group: Parametrizing the exposure of superparamagnetic iron oxide nanoparticles in cell cultures at different in vitro environments. We congratulate the authors Maria Milla, Si-Ming Yu and  Anna Laromaine for this publication in the Chemical Engineering Journal: https://doi.org/10.1016/j.cej.2017.12.070
That is certainly a good Xmas present for the N&N group!
 
 

Hot off the press: Published paper in The Journal of Physical Chemistry Letters

Congratulations to Anna Roig and the other co-autors for the paper: Ultrafast Synthesis and Coating of High-Quality β-NaYF4:Yb3+,Ln3+ Short Nanorods.
The paper was been published this November 2017 in The Journal of Physical Chemistry Letters! 

Abstract: An ultrafast route to prepare up-converting single β-phase NaYF4:Yb3+,Ln3+ (Ln: Er, Tm, or Tb) short nanorods (UCNRs) of high quality was developed. This new procedure affords reactive surface nanorods that are easily coated by direct injection of suitable capping ligands. Thus highly crystalline nanorods with excellent UC fluorescence and good solvent-selective dispersion are obtained, which represents a significant advance in the field and enlarges their use for biomedical and other technological applications. Unlike other methodologies, the short reaction time provides a kinetic control over crystallization processes, and the β-phase and rod morphology is preserved regardless of the optically active Ln3+ ion. The UC emission was finely tuned by using the most popular Yb3+/Tm3+ and Yb3+/Er3+ pairs. More importantly, UCNRs doped with the unusual Yb3+/Tb3+ pair, with no ladder-like energy levels, provided a nice emission upon near-infrared excitation, which constitutes the first example of phonon-assisted cooperative sensitization to date in pure β-NaYF4 nanocrystals.