Porous silicon microparticles as efficient carriers for immunologic adjuvants

In this work we report a first-time combination of porous silicon (pSi) particles with the immunologic adjuvant Pam3CSK4, a TLR 1/2 agonist, as a tool for immunotherapy. pSi is a sponge-like biocompatible and biode gradable nanomaterial with high porosity, large surface-to-volume ratio and tunable surface, suitable for drug delivery applications. This study provides, by means of live-cell confocal microscopy, an insight about the time course of the interaction of free Pam3CSK4 vs vectorized by pSi microparticles with human dendritic cells (DCs). We found a delay in the ingestion of the agonist when carried by pSi microparticles. These findings were sup ported by the observation of the morphological changes related to the activation of DCs that occurred with a 5 h difference when treated with the vectorized ligand. These results provide the first demonstration of pSi as a conceivable candidate to deliver Pam3CSK4 to DCs paving the way towards immunotherapy practice

Viscosity, Boson Peak and Elastic Moduli in the Na2O-SiO2 System

The temperature and chemical dependence of the melt viscosity are ubiquitous in the model development of the volcanic dynamics, as well as in the glass production and design. We focussed on the yet-explored relationship between the bulk and shear moduli ratio and boson peak with the melt fragility of their parental glasses. Here, we explored the extension of the observed trend by testing the conventional binary system Na2O-SiO2, thus providing new evidence supporting the link between the flow of melts and supercooled liquids and the vibrational dynamics of their parental glasses. This was accomplished by integrating new low-frequency Raman measurements and integrating data from the literature on Brillouin light scattering and viscometry. This approach allows us to feed the MYEGA equation with reliable input parameters to quantitatively predict the viscosity of the Na2O-SiO2 system from the liquid up to the glass transition

Role of interface region on the optoelectronic properties of silicon nanocrystals embedded in SiO2

Light emitting silicon nanocrystals embedded in SiO2 have been investigated by x-ray absorption measurements in total electron and photoluminescence yields, by energy filtered TEM analysis and by ab-initio total energy calculations. Both experimental and theoretical results show that the interface between the silicon nanocrystals and the surrounding SiO2 is not sharp: an intermediate region of amorphous nature and of variable composition links the crystalline Si with the amorphous stoichiometric SiO2. This region plays an active role in the light emission process

3D Imaging on heterogeneous surfaces on laterite drill core materials

The SOLSA project aims to construct an analytical expert system for on-line-on-mine-real-time mineralogical and geochemical analyses on sonic drilled cores. A profilometer is indispensable to obtain reliable and quantitative data from RGB and hyperspectral cameras, and to get 3D definition of close-to-surface objects such as rheology (grain shape, grain size, fractures and vein systems), material hardness and porosities. Optical properties of minerals can be analyzed by focusing on the reflectance. Preliminary analyses were performed with the commercial scan control profilometer MI-CRO-EPSILON equipped with a blue 405 nm laser on a conveyor belt (depth resolution: 10 μm; surface resolution: 30x30 μm2 (maximum resolution; 1m drill core/4 min). Drill core parts and rocks with 4 different surface roughness states: (1) sonic drilled, (2) diamond saw-cut, polished at (3) 6 mm and (4) 0.25 μm were measured (see also abstract Duée et al. this volume). The ΜICRO- EPSILON scanning does not detect such small differences of surface roughness states. Profilometer data can also be used to access rough mineralogical identification of some mineral groups like Fe-Mg silicates, quartz and feldspars). Drill core parts from a siliceous mineralized breccia and laterite with high and deep porosity and fractures were analyzed. The determination of holes’ convexity and fractures) is limited by the surface/depth ratio. Depending on end-user’s needs, parameters such as fracture densities and mineral content should be combined, and depth and surface resolutions should be optimized, to speed up “on-line-on-mine-real- time” mineral and chemical analyses in order to reach the target of about 80 m/day of drilled core

Efficient long-term open-access data archiving in mining industries

Efficient data collection, analysis and preservation are needed to accomplish adequate business decision making. Long-lasting and sustainable business operations, such as mining, add extra requirements to this process: data must be reliably preserved over periods that are longer than that of a typical software life-cycle. These concerns are of special importance for the combined on-line-on-mine-real-time expert system SOLSA (http://www.solsa-mining.eu/) that will produce data not only for immediate industrial utilization, but also for the possible scientific reuse. We thus applied the experience of scientific data publishing to provide efficient, reliable, long term archival data storage. Crystallography, a field covering one of the methods used in the SOLSA expert system, has long traditions of archiving and disseminating crystallographic data. To that end, the Crystallographic Interchange Framework (CIF, [1]) was developed and is maintained by the International Union of Crystallography (IUCr). This framework provides rich means for describing crystal structures and crystallographic experiments in an unambiguous, human- and machine- readable way, in a standard that is independent of the underlying data storage technology. The Crystallography Open Database (COD, [2]) has been successfully using the CIF framework to maintain its open-access crystallographic data collection for over a decade [3,4]. Since the CIF framework is extensible it is possible to use it for other branches of knowledge. The SOLSA system will generate data using different methods of material identification: XRF, XRD, Raman, IR and DRIFT spectroscopy. For XRD, the CIF is usable out-of-the-box, since we can rely on extensive data definition dictionaries (ontologies) developed by the IUCr and the crystallographic community. For spectroscopic techniques such dictionaries, to our best knowledge, do not exist; thus, the SOLSA team is developing CIF dictionaries for spectroscopic techniques to be used in the SOLSA expert system. All dictionaries will be published under liberal license and communities are encourage to join the development, reuse and extend the dictionaries where necessary. These dictionaries will enable access to open data generated by SOLSA by all interested parties. The use of the common CIF framework will ensure smooth data exchange among SOLSA partners and seamless data publication from the SOLSA project

Etude de la structure locale et de la luminescence de matériaux optoélectroniques par spectroscopie d'absorption des rayons X

Dans ce travail experimental, des systèmes confinés de silicum tels que le silicum poreux et des nanocristaux de silicum dans la silice amorphe ont été étudiés, dans le but de contribuer au débat concernant les mécanismes d'émission de luminescence. L'idée centrale était de trouver une corrélation entre les propriétés optiques et structurales afin de caractériser les sites luminescents. Pour cela, nous avons utilisé les potentialités de la spectroscopie d'absorption des rayons X ; des spectres de "total electonyied" (TEY) et de "photo-luminescence yied" (PLY) ont été analysés (EXAFS ou XANES) pour obtenir des informations électroniques et structurales. La comparaison entre TEY et PLY a permis de carctériser les nanostructures luminescentes à l'aide d'une interprétation basée sur la sélectivité de la technique PLY aux sites luminescents. L'étude du silicium poreux a mis en évidence le lien existant entre la préparation des échantillons et les caractéristiques optiques et struturales. Nos mesures ont montré que le mécanisme d'émission est surtout dû au confinement quantique des nanostructures; cependant l'influence de la passivation de la surface, particulièrement celle des oxydes et hydroxides, ne peut être négligée. L'étude des nanocristaux de silicum dans la silice amorphe a été effectuée grâce à la sensitivité de la technique PLY et nous a conduit à une caractérisation structurale de la région d'interface entre les nanocristaux et la matrice de silice amorphe. L'interprétation des résultats expérimentaux a été menée conjointement avec une discussion plus générale sur la sélectivité de la technique PLY, comportant une comparaison critique avec d'autres travaux reportés dans la littérature. Nous avons montré qu'il est possible non seulement de distinguer les nanostructures luminescentes des nanostructures non-luminescentes, mais de sélectionner différentes sites luminescents par l'intermédiaire de leur énergie d'émission (PLY partiel).GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Photonics applications

Photonics applications of silicon nanocrysta

Light emitting porous silicon microparticles: from fabrication to surface functionalization

fabrication ans post-fabrication procedure to obtain porous silicon microparticles for theranostic application

Ultrasonication effect on size distribution of functionalized porous silicon microparticles

Sponge-like luminescent mesoporous silicon microparticles are produced from crystalline silicon with a simple and cheap top-down fabrication process which, however, offers scarce control of structural features such size, size distribution and pore dimensions of the final product. Herein, we report on a post-fabrication procedure based on ultrasonic treatment to get more homogeneous size distribution and much more control on the average dimension of the microparticles. We investigated the effect of variable ultrasonic treatments on the structural and optical properties of the microparticles. Thestructure was analysed both at micro and nano scale and for microparticles in dried state and in solution. We proved that few minutes of sonication strongly limits the heterogeneity of the sample size, without affecting the optical properties and porous structure. This simple post-fabrication step offers new opportunities for successful use of silicon microparticles in biomedicine