Assemblées de nanoparticules magnétiques pour le développement de matériaux présentant de nouvelles propriétés

The magnetic properties of nanoparticle assemblies are dependent on the intrinsic properties (size, shape and chemical composition) of the nanoparticles, as well as on their organization. The elaboration of an assembly of well-controlled nanoparticles is of interest for the development of materials with new properties, as well as for the study of the influence of the different parameters of the nanoparticle assembly on the magnetic properties. Our approach is the combination of i) the controlled formation of the nanoparticles using the ordered mesoporosity of a silica monolith, prepared by a template-assisted sol-gel method, and ii) the use of Prussian blue analogues (PBA), in which the metal centers are mixed at the atomic scale. The ordered silica monolith enables us to control the size, shape and organization of the nanoparticles, whereas the use of PBA presents the advantage to control the chemical composition of the nanoparticles.In this work, we have prepared Co/SiO2, CoFe/SiO2 and Fe/SiO2 nanocomposites by thermal treatment under oxidizing and reducing atmosphere by using two synthesis pathways, which vary in the choice of precursor (PBA or nitrate salts). The study of the magnetic behaviors reveals a surprising but significant influence of the synthesis pathway. Microstructures for the nanocomposites and their relationship to the magnetic properties could be established. Furthermore, the impact of the organization of the magnetic nanoparticles on the magnetic properties of one macroscopic monolith piece oriented in a magnetic field was studied and the results are discussed.Les propriétés magnétiques d’une assemblée de nanoparticules sont dépendantes des propriétés intrinsèques (taille, forme et composition chimique) des nanoparticules, ainsi que de leur organisation. La formation d'une assemblée de nanoparticules bien contrôlée présente un intérêt pour le développement de matériaux avec de nouvelles propriétés, ainsi que pour l'étude de l'influence des différents paramètres de l’assemblée sur les propriétés magnétiques. Notre approche combine i) la formation contrôlée de nanoparticules grâce à l’utilisation de la mésoporosité ordonnée d'un monolithe de silice, préparé par une méthode sol-gel, et ii) l'utilisation d'analogues du bleu de Prusse (ABP), dans lesquels les centres métalliques sont mélangés à l'échelle atomique. Le monolithe de silice permet de contrôler la taille, la forme et l'organisation des nanoparticules, tandis que l'utilisation de l’ABP présente l'avantage de permettre le contrôle de la composition chimique des nanoparticules.Dans ce travail, nous avons préparé par traitement thermique sous atmosphère oxydante et réductrice des nanocomposites Co/SiO2, CoFe/SiO2 et Fe/SiO2, en utilisant deux voies de synthèse, qui varient dans le choix du précurseur (ABP ou sels de nitrate). L'étude des comportements magnétiques révèle une influence surprenante et significative de la voie de synthèse. Les microstructures des nanocomposites et leur relation avec les propriétés magnétiques ont pu être établies. De plus, l'impact de l'organisation des nanoparticules magnétiques sur les propriétés magnétiques d’une pièce de monolithe macroscopique orienté dans un champ magnétique a été étudié et les résultats sont discutés

Assemblées de nanoparticules magnétiques pour le développement de matériaux présentant de nouvelles propriétés

Les propriétés magnétiques d’une assemblée de nanoparticules sont dépendantes des propriétés intrinsèques (taille, forme et composition chimique) des nanoparticules, ainsi que de leur organisation. La formation d'une assemblée de nanoparticules bien contrôlée présente un intérêt pour le développement de matériaux avec de nouvelles propriétés, ainsi que pour l'étude de l'influence des différents paramètres de l’assemblée sur les propriétés magnétiques. Notre approche combine i) la formation contrôlée de nanoparticules grâce à l’utilisation de la mésoporosité ordonnée d'un monolithe de silice, préparé par une méthode sol-gel, et ii) l'utilisation d'analogues du bleu de Prusse (ABP), dans lesquels les centres métalliques sont mélangés à l'échelle atomique. Le monolithe de silice permet de contrôler la taille, la forme et l'organisation des nanoparticules, tandis que l'utilisation de l’ABP présente l'avantage de permettre le contrôle de la composition chimique des nanoparticules.Dans ce travail, nous avons préparé par traitement thermique sous atmosphère oxydante et réductrice des nanocomposites Co/SiO2, CoFe/SiO2 et Fe/SiO2, en utilisant deux voies de synthèse, qui varient dans le choix du précurseur (ABP ou sels de nitrate). L'étude des comportements magnétiques révèle une influence surprenante et significative de la voie de synthèse. Les microstructures des nanocomposites et leur relation avec les propriétés magnétiques ont pu être établies. De plus, l'impact de l'organisation des nanoparticules magnétiques sur les propriétés magnétiques d’une pièce de monolithe macroscopique orienté dans un champ magnétique a été étudié et les résultats sont discutés.The magnetic properties of nanoparticle assemblies are dependent on the intrinsic properties (size, shape and chemical composition) of the nanoparticles, as well as on their organization. The elaboration of an assembly of well-controlled nanoparticles is of interest for the development of materials with new properties, as well as for the study of the influence of the different parameters of the nanoparticle assembly on the magnetic properties. Our approach is the combination of i) the controlled formation of the nanoparticles using the ordered mesoporosity of a silica monolith, prepared by a template-assisted sol-gel method, and ii) the use of Prussian blue analogues (PBA), in which the metal centers are mixed at the atomic scale. The ordered silica monolith enables us to control the size, shape and organization of the nanoparticles, whereas the use of PBA presents the advantage to control the chemical composition of the nanoparticles.In this work, we have prepared Co/SiO2, CoFe/SiO2 and Fe/SiO2 nanocomposites by thermal treatment under oxidizing and reducing atmosphere by using two synthesis pathways, which vary in the choice of precursor (PBA or nitrate salts). The study of the magnetic behaviors reveals a surprising but significant influence of the synthesis pathway. Microstructures for the nanocomposites and their relationship to the magnetic properties could be established. Furthermore, the impact of the organization of the magnetic nanoparticles on the magnetic properties of one macroscopic monolith piece oriented in a magnetic field was studied and the results are discussed

Co, Fe and CoFe oxide nanoparticle assemblies within an ordered silica matrix: effects of the metal ions and synthesis pathway on the microstructure and magnetic properties

The magnetic properties of nanoparticle assemblies strongly depend on the structural and morphological characteristics of the individual nanoparticles as well as on their organization within the assembly. Here, we present the synthesis of cobalt and/or iron oxide nanoparticles within the ordered mesoporosity of a silica monolith by two different synthesis pathways (using either Prussian blue analogues or nitrate salts as a precursor). We describe the influence of the nature of the metal ion and of the synthesis pathway on the morphology of the nanoparticles. With respect to these observations, we present and discuss the temperature-dependent magnetic behaviors of the final nanocomposites

Transforming a Diamagnetic Ordered Mesoporous Silica Monolith into a Room Temperature Permanent Magnet through Multiscale Control of the Magnetic Properties

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Aerogelation of Polymer-Coated Photoluminescent, Plasmonic, and Magnetic Nanoparticles for Biosensing Applications

[Image: see text] Macroscopic materials with nanoscopic properties have recently been synthesized by self-assembling defined nanoparticles to form self-supported networks, so-called aerogels. Motivated by the promising properties of this class of materials, the search for versatile routes toward the controlled assembly of presynthesized nanoparticles into such ultralight macroscopic materials has become a great interest. Overcoating procedures of colloidal nanoparticles with polymers offer versatile means to produce aerogels from nanoparticles, regardless of their size, shape, or properties while retaining their original characteristics. Herein, we report on the surface modification and assembly of various building blocks: photoluminescent nanorods, magnetic nanospheres, and plasmonic nanocubes with particle sizes between 5 and 40 nm. The polymer employed for the coating was poly(isobutylene-alt-maleic anhydride) modified with 1-dodecylamine side chains. The amphiphilic character of the polymer facilitates the stability of the nanocrystals in aqueous media. Hydrogels are prepared via triggering the colloidally stable solutions, with aqueous cations acting as linkers between the functional groups of the polymer shell. Upon supercritical drying, the hydrogels are successfully converted into macroscopic aerogels with highly porous, open structure. Due to the noninvasive preparation method, the nanoscopic properties of the building blocks are retained in the monolithic aerogels, leading to the powerful transfer of these properties to the macroscale. The open pore system, the universality of the polymer-coating strategy, and the large accessibility of the network make these gel structures promising biosensing platforms. Functionalizing the polymer shell with biomolecules opens up the possibility to utilize the nanoscopic properties of the building blocks in fluorescent probing, magnetoresistive sensing, and plasmonic-driven thermal sensing

Flexible Targeting of ErbB Dimers That Drive Tumorigenesis by Using Genetically Engineered T Cells

Pharmacological targeting of individual ErbB receptors elicits antitumor activity, but is frequently compromised by resistance leading to therapeutic failure. Here, we describe an immunotherapeutic approach that exploits prevalent and fundamental mechanisms by which aberrant upregulation of the ErbB network drives tumorigenesis. A chimeric antigen receptor named T1E28z was engineered, in which the promiscuous ErbB ligand, T1E, is fused to a CD28 + CD3ζ endodomain. Using a panel of ErbB-engineered 32D hematopoietic cells, we found that human T1E28z+ T cells are selectively activated by all ErbB1-based homodimers and heterodimers and by the potently mitogenic ErbB2/3 heterodimer. Owing to this flexible targeting capability, recognition and destruction of several tumor cell lines was achieved by T1E28z+ T cells in vitro, comprising a wide diversity of ErbB receptor profiles and tumor origins. Furthermore, compelling antitumor activity was observed in mice bearing established xenografts, characterized either by ErbB1/2 or ErbB2/3 overexpression and representative of insidious or rapidly progressive tumor types. Together, these findings support the clinical development of a broadly applicable immunotherapeutic approach in which the propensity of solid tumors to dysregulate the extended ErbB network is targeted for therapeutic gain