Monodisperse magnetic nanoparticle assemblies prepared at scale by competitive stabiliser desorption

We report a scalable and reproducible method to assemble magnetic nanoparticle clusters from oleic acid stabilised iron oxide nanoparticles. By controlling the surface coverage of oleic acid on the nanoparticle surface we have achieved controlled nanoparticle assembly following exposure of the suspension to a substrate layer of cyanopropyl-modified silica which competes for the ligand. The clusters can be formed reproducibly and their final size can be selected over a range covering almost two orders of magnitude. Most unusually, the relative monodispersity of the cluster suspension is improved compared to the starting nanoparticle suspension, and the yield is close to 100%. Interestingly, we find that the kinetics of assembly is not altered by scaling up, which is surprising for a complex process involving molecular transport. Kinetic studies provided mechanistic insight into the process, and suggested general requirements for controlled assembly of other nanoparticle types

Size-Controlled Nanoparticle Clusters of Narrow Size- Polydispersity Formed Using Multiple Particle Types Through Competitive Stabilizer Desorption to a Liquid– Liquid Interface

A novel colloidal approach is presented for preparing fully dispersed nanoparticle (NP) assemblies (clusters) of narrow size-polydispersity over a wide range of sizes through irreversible depletion of stabilizing ligands onto a liquid–liquid interface. Unusually, the relative monodispersity of the assemblies continuously improves throughout the process. A detailed kinetics study into the assembly of iron oxide NP clusters shows that the assembly rate decreases with NP concentration, pinpointing the role of the interface in size focusing. A new protocol for identifying initial conditions that enable controlled assembly is described, which allows extension of the approach to multiple NP types, opening up a general route to colloidally processed materials. The process uses cheap materials, it is reproducible, robust, and scaleable, and it allows for selection of both particle and cluster size. In the case of assemblies of magnetic iron oxide NPs, these advantages enable tuning of the magnetic properties of the assemblies for applications such as magnetically targetable MRI-trackable agents in biomedicine

Covalent functionalization of multi-walled carbon nanotubes with a gadolinium chelate for efficient T1-weighted magnetic resonance imaging

Given the promise of carbon nanotubes (CNTs) for photothermal therapy, drug delivery, tissue engineering, and gene therapy, there is a need for non-invasive imaging methods to monitor CNT distribution and fate in the body. In this study, non-ionizing whole-body high field magnetic resonance imaging (MRI) is used to follow the distribution of water-dispersible non-toxic functionalized CNTs administrated intravenously to mice. Oxidized CNTs are endowed with positive MRI contrast properties by covalent functionalization with the chelating ligand diethylenetriaminepentaacetic dianhydride (DTPA), followed by chelation to Gd. The structural and magnetic properties, MR relaxivities, cellular uptake, and application for MRI cell imaging of Gd-CNTs in comparison to the precursor oxidized CNTs are evaluated. Despite the intrinsic T contrast of oxidized CNTs internalized in macrophages, the anchoring of paramagnetic gadolinium onto the nanotube sidewall allows efficient T contrast and MR signal enhancement, which is preserved after CNT internalization by cells. Hence, due to their high dispersibility, Gd-CNTs have the potential to produce positive contrast in vivo following injection into the bloodstream. The uptake of Gd-CNTs in the liver and spleen is assessed using MRI, while rapid renal clearance of extracellular Gd-CNTs is observed, confirming the evidences of other studies using different imaging modalities

Photoluminescence and cathodoluminescence of Eu:La2O3 nanoparticles synthesized by several methods

Abstract : Europium-doped La2O3 nanocrystalline powders with sizes ranging from 4 nm to 300 nm have been obtained by the modified Pechini, hydrothermal with conventional furnace, hydrothermal with microwave furnace, and precipitation with ultrasonic bath methods. X-ray diffraction techniques were used to study the evolution of the prepared gels towards the desired crystalline phase. We determined the size and the morphology of the nanoparticles by electronic microscopy. Finally, we studied and analyzed the luminescence properties of the trivalent europium in the hexagonal La2O3 nanocrystals by photoluminescence and cathodoluminescence

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed

コウブンシ ヒフクカ ガンマ - Fe2O3 ナノ ビリュウシ : ゴウセイ オヨビ ブッセイ

京都大学0048新制・課程博士博士(理学)甲第11051号理博第2829号新制||理||1421(附属図書館)22583UT51-2004-J723京都大学大学院理学研究科化学専攻(主査)教授 高野 幹夫, 教授 島川 祐一, 教授 梅村 純三学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

Synthesis and magnetic properties of the gamma-Fe2O3/poly-(methyl methacrylate)-core/shell nanoparticles

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