Iron Oxide Nanoparticle Clusters Research Articles

Flow-mediated stem cell labeling with superparamagnetic iron oxide nanoparticle clusters.

This study presents a strategy to enhance the uptake of superparamagnetic iron oxide nanoparticle (SPIO) clusters by manipulating the cellular mechanical environment. Specifically, stem cells exposed to an orbital flow ingested almost a 2-fold greater amount of SPIO clusters than those cultured statically. Improvements in magnetic resonance (MR) contrast were subsequently achieved for labeled cells in collagen gels and a mouse model. Overall, this strategy will serve to improve the efficiency of cell tracking and therapies.

Self-Assembled Fe3O4 Nanoparticle Clusters as High-Performance Anodes for Lithium Ion Batteries via Geometric Confinement

Although different kinds of metal oxide nanoparticles continue to be proposed as anode materials for lithium ion batteries (LIBs), their cycle life and power density are still not suitable for commercial applications. Metal oxide nanoparticles have a large storage capacity, but they suffer from the excessive generation of solid-electrolyte interphase (SEI) on the surface, low electrical conductivity, and mechanical degradation and pulverization resulted from severe volume expansion during cycling. Herein we present the preparation of mesoporous iron oxide nanoparticle clusters (MIONCs) by a bottom-up self-assembly approach and demonstrate that they exhibit excellent cyclic stability and rate capability derived from their three-dimensional mesoporous nanostructure. By controlling the geometric configuration, we can achieve stable interfaces between the electrolyte and active materials, resulting in SEI formation confined on the outer surface of the MIONCs.

An NMR-relaxation study of the effect of albumin on aggregation of magnetic iron oxide nanoparticles

The dependence of the aggregation of magnetic iron oxide nanoparticles in aqueous suspensions under the action of human serum albumin is analyzed based on the data of proton magnetic relaxation. It is shown that albumin adsorption on magnetic nanoparticles gives rise to the formation of a protein corona and clusters of magnetic nanoparticles, decreasing the aggregation stability of the suspension in a 7.1-T magnetic field. Clustering of magnetic iron oxide nanoparticles enhances the relaxation efficiency of magnetic suspensions during NMR measurements.

Polyethylene glycol-based biocompatible and highly stable superparamagnetic iron oxide nanoclusters for magnetic resonance imaging

We developed a simple emulsion and solvent-evaporation approach for the clustering of iron oxide nanoparticles using a polyethylene glycol (PEG)-based nonionic surfactant, D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS). To obtain well-constructed clusters of iron oxide nanoparticles (IONPs), the synthetic parameters (the solvent systems and reaction temperature) were investigated. The rate of solvent evaporation is critical to optimise the formation of clusters which were spherical in shape, had a diameter of approximately 97 nm, and were highly stable for storage at room temperature. This greener synthetic approach displays the benefits of high yield and waste reduction compared to previous reports. In addition, IONP clusters of 50 μg mL−1 retained over 84% of the viability of KB cells and the structure of the clusters can be observed by transmission electron microscopy after cellular internalisation. The mechanism of cellular uptake of the IONP clusters was speculated to be via an energy-dependent endocytic pathway because the internalisation was significantly inhibited at 4 °C. These IONP clusters also had higher saturation magnetisation and r2 relaxation (253.85 s−1 mM−1) values and better T2-weighted contrast performance (r2/r1 = 20.5) than commercial Resovist®. The contrast signal for magnetic resonance imaging was efficiently increased by the IONP clusters in vivo, especially in the liver and tumour regions. Iron staining of both tissues confirmed the accumulation of the nanoparticles in both areas. Thus, these clusters, which were prepared with the use of a nonionic polymer surfactant, can potentially serve as efficient contrast agents for magnetic resonance applications.

Clusters of Superparamagnetic Iron Oxide Nanoparticles Encapsulated in a Hydrogel: A Particle Architecture Generating a Synergistic Enhancement of the T2 Relaxation

Clusters of iron oxide nanoparticles encapsulated in a pH-responsive hydrogel are synthesized and studied for their ability to alter the T(2)-relaxivity of protons. Encapsulation of the clusters with the hydrophilic coating is shown to enhance the transverse relaxation rate by up to 85% compared to clusters with no coating. With the use of pH-sensitive hydrogel, difficulties inherent in comparing particle samples are eliminated and a clear increase in relaxivity as the coating swells is demonstrated. Agreement with Monte Carlo simulations indicates that the lower diffusivity of water inside the coating and near the particle surface leads to the enhancement. This demonstration of a surface-active particle structure opens new possibilities in using similar structures for nanoparticle-based diagnostics using magnetic resonance imaging.

Nanomagnetism reveals the intracellular clustering of iron oxide nanoparticles in the organism

There are very few methods to investigate how nanoparticles (NPs) are taken up and processed by cells in the organism in the short and long terms. We propose a nanomagnetism approach, in combination with electron microscopy, to document the magnetic outcome of iron oxide-based P904 NPs injected intravenously into mice. The NP superparamagnetic properties are shown to be modified by cell internalization, due to magnetic interactions between NPs sequestered within intracellular organelles. These modifications of magnetic behaviour are observed in vivo after NP uptake by resident macrophages in spleen and liver or by inflammatory macrophages in adipose tissue as well as in vitro in monocyte-derived macrophages. The dynamical magnetic response of cell-internalized NPs is theoretically and experimentally evidenced as a global signature of their local organization in the intracellular compartments. The clustering of NPs and their magnetism become dependent on the targeted organ, on the dose administrated and on the time elapsed since their injection. Nanomagnetism probes the intracellular clustering of iron-oxide NPs and sheds light on the impact of cellular metabolism on their magnetic responsivity.

Facile synthesis and morphology evolution of magnetic iron oxide nanoparticles in different polyol processes

A series of magnetic iron oxide nanoparticle clusters and porous nanoparticles with high magnetization are synthesized using the polyols with different reductive abilities. To investigate the morphology evolution in a polyol process, HRTEM is used to study the products. When ethylene glycol is used as the solvent, iron oxide nanoparticles form and then self-assemble into compact nanoparticle clusters (ca. 300 nm) through oriented attachment growth with a few misarranged nanoparticles in the clusters. At last these clusters develop into flower-like clusters with single crystal-like diffraction. When 1,2-propylene glycol is employed as the solvent, iron oxide nanoparticles quickly self-assemble into nanoparticle clusters (ca. 50 nm) with many misarrangements. As the reaction time extends, these clusters collapse and split into porous nanoparticles. According to the morphology evolution of iron oxide nanoparticles in different polyols, we propose our reasonable supposition on the whole process. These findings may help to understand the role of the polyol as solvent and obtain the novel secondary structures of nanoparticles in a polyol process.