Congratulations Jan! Today we announce that the previous work of the PhD student Jan Grzelak has been recently published on the journal Nanomaterials . This work is based on the Bachelor’s project he did in Warsaw under the supervision of Dr. Wiktor Lewandowski.
Paper abstract: By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required. Here, we report a new method for tuning structural properties of assemblies of nanoparticles grafted with a mixture of promesogenic and alkyl thiols, by varying design of the latter. As a model system, we used Ag and Au nanoparticles that were coated with three-ring promesogenic molecules and dodecanethiol ligand. These LC NPs self-assemble into switchable lamellar (Ag NPs) or tetragonal (Au NPs) aggregates, as determined with small angle X-ray diffraction and transmission electron microscopy. Reconfigurable assemblies of Au NPs with different unit cell symmetry (orthorombic) are formed if hexadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol were used in the place of dodecanethiol; in the case of Ag NPs the use of 11-hydroxyundecanethiol promotes formation of a lamellar structure as in the reference system, although with substantially broader range of thermal stability (140 vs. 90 °C). Our results underline the importance of alkyl ligand functionalities in determining structural properties of liquid-crystalline nanoparticles, and, more generally, broaden the scope of synthetic tools available for tailoring properties of reversibly reconfigurable plasmonic nanomaterials
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.
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.
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.
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 paper describes a novel and convenient synthetic strategy for the preparation of magnetically responsive silica nanospheres decorated with mixed ligand protected gold nanoparticles. Gold nanoparticles are attached to the silica surface via stable amide bond formation. The hierarchical nanospheres show promising results as a reusable and efficient catalyst for esterification reactions and they can be recovered through a simple magnetic separation.
Figure: Schematic illustration of: (a) the partial ligand exchange of 3-mercapto-1-propanesulfonate (MPSA):1-octanethiol(OT) covered gold nanoparticles, (b) the synthesis of core-shell magnetic silica and (c) the synthesis of the magnetic silica decorated with gold nanoparticles hierarchical nanospheres.
The manuscript will be presented and discussed at a forthcoming Faraday Discussions meeting, this next summer. During the meeting, all delegates will be able to contribute to the debate, which will be included in the final volume. This will be a great opportunity to discuss the formation mechanism of the magnetic gold nanotriangles with some experts on this field.
The combination of iron oxide and gold in a single nanoparticle results in both magnetic and plasmonic properties that can stimulate novel applications in bio-sensing, medical imaging, or therapeutics. Microwave heating method allows the fabrication of multi-component, multi-functional nanostructures by promoting selective heating at desired sites. Recently, we reported a microwave-assisted polyol route yielding gold nanotriangles decorated with iron oxide nanoparticles (1). Here, we present an in-depth microstructural and compositional characterization of the system by using scanning transmission electron microscopy (STEM) and electron energy loss (EELS) spectroscopy. A method to remove the iron oxide nanoparticles from the gold nanocrystals and some insights on crystal nucleation and growth mechanisms are also provided.
Figure: (a) Schematic representation of the synthesis route. (b) HRTEM image of a Au NH-SPIONs and a Au NT-SPIONs. Characterization of the heterostructures: (c) UV-Vis-NIR spectra. (d) Hydrodynamic diameter of the Au-SPIONS measured by DLS. (e) Magnetization curve up to 6 T at 5K.
The work has resulted from a collaboration between the ICMAB, the CNM and the company Dropsens.
Screen-printed electrodes made of a bismuth nanoparticle porous carbon nanocomposite material applied to the detection of heavy metals (Pengfei Niu, César Fernández-Sánchez,* Martí Gich,* Carla Navarro-Hernández, Pablo Fanjul-Bolado, and Anna Roig, Microchimica Acta, , Volume 183, Issue 2, pp 617-623).
This work reports on the simplified fabrication and on the characterization of bismuth-based screen-printed electrodes (SPEs) for use in heavy metal detection. A nanocomposite consisting of bismuth nanoparticles and amorphous carbon was synthesized by a combined one-step sol-gel and pyrolysis process and milled down to a specific particle size distribution as required for the preparation of an ink formulation to be used in screen printing. The resulting electrochemical devices were applied to the detection of Pb(II) and Cd(II) ions in water samples.
The porous structure of carbon and the high surface area of the bismuth nanoparticles allow for the detection of Pb(II) and Cd(II) at concentration levels below 4 ppb. The application of the SPEs was demonstrated by quantifying these ions in tap drinking water and wastewater collected from an influent of an urban wastewater treatment plant.