Synthesis and magnetic properties of Fe3O4 nanoparticles coated with biocompatible double hydrophilic block copolymer

LAPONITE® nanodisk-"decorated" Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability

Magnetic Fe₃O₄ nanoparticles "decorated" by LAPONITE® nanodisks have been materialized utilizing the Schikorr reaction following a facile approach and tested as mediators of heat for localized magnetic hyperthermia (MH) and as magnetic resonance imaging (MRI) agents. The synthetic protocol involves the interaction between two layered inorganic compounds, ferrous hydroxide, Fe(OH)₂, and the synthetic smectite LAPONITE® clay Na_0.7⁺[(Si₈Mg_5.5Li_0.3)O₂₀(OH)₄]_0.7^-, towards the formation of superparamagnetic Fe₃O₄ nanoparticles, which are well decorated by the diamagnetic clay nanodisks. The latter imparts high negative ζ-potential values (up to -34.1 mV) to the particles, which provide stability against flocculation and precipitation, resulting in stable water dispersions. The obtained LAPONITE®-"decorated" Fe₃O₄ nanohybrids were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, dynamic light scattering (DLS) and vibrating sample magnetometry (VSM) at room temperature, revealing superior magnetic hyperthermia performance with specific absorption rate (SAR) values reaching 540 W g_Fe^-1 (28 kA m^-1, 150 kHz) for the hybrid material with a magnetic loading of 50 wt% Fe₃O₄/LAPONITE®. Toxicity studies were also performed with human glioblastoma (GBM) cells and human foreskin fibroblasts (HFF), which show negligible to no toxicity. Furthermore, T₂-weighted MR imaging of rodent brain shows that the LAPONITE®-"decorated" Fe₃O₄ nanohybrids predominantly affected the transverse T₂ relaxation time of tissue water, which resulted in a signal drop on the MRI T₂-weighted imaging, allowing for imaging of the magnetic nanoparticles.

Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids' surface functionalization in a nonpolar solvent.

Facile solvothermal preparation of Fe3O4–Ag nanocomposite with excellent catalytic performance

Functional nanocomposites demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. Magnetic nanocomposites are an important type of composite materials, due to their applications in optics, medicine and catalysis. In this report, a new Fe₃O₄-loaded silver (Fe₃O₄–Ag) nanocomposite has been successfully synthesized via a simple solvothermal method and in situ growth of silver nanowires. The silver nanowires were prepared via the reduction of silver vanadate with the addition of uniformly dispersed Fe₃O₄ nanoparticles. Structural and morphological characterizations of the obtained Fe₃O₄–Ag nanocomposite were carried out using many characterization methods. As a new composite catalyst, the synthesized magnetic Fe₃O₄–Ag nanocomposite displayed a high utilization rate of catalytically active sites in catalytic reaction medium and showed good separation and recovery using an external magnetic field. The facile preparation and good catalytic performance of this Fe₃O₄–Ag nanocomposite material demonstrate its potential applications in catalytic treatment and composite materials.

A new Fe₃O₄–Ag nanocomposite was prepared via solvothermal method, demonstrating potential application in catalytic degradation of wastewater treatment and composite materials.

High Quality Multicellular Tumor Spheroid Induction Platform Based on Anisotropic Magnetic Hydrogel

In recent years, multicellular spheroid (MCS) culture has been extensively studied both in fundamental research and application fields since it inherits much more characteristics from in vivo solid tumor than conventional two-dimensional (2D) cell culture. However, anticell adhesive MCS culture systems such as hanging drop allow certain cell lines only to form loose, irregular aggregates rather than MCS with physiological barriers and pathophysiological gradients, which failed to mimic in vivo solid tumor in these aspects. To address this issue, we improved our previously established anisotropic magnetic hydrogel platform, enabling it to generate multicellular spheroids with higher efficiency. The qualities of multicellular tumor spheroids (MCTSs) obtained on our platform and from classic 3D culture systems were compared in terms of morphology, biological molecule expression profiles, and drug resistance. In this novel platform, mature MCTSs with necrotic cores could be observed in 1 week. And results of molecular biological assays with real time-PCR and western-blot confirmed that MCTSs obtained from our platform performed higher cell pluripotency than those obtained from the hanging drop system. Moreover, a lower cell apoptosis ratio and better viability of cancer cells were observed on our platform both under culturing and drug treatment. In conclusion, higher quality of MCTSs obtained from this anisotropic magnetic hydrogel than classic hanging drop system validate its potential to be an in vitro platform of inducing tumor MCTS formation and drug efficacy evaluation.

Azide-alkyne Huisgen [3+2] cycloaddition using CuO nanoparticles

Recent developments in the synthesis of CuO nanoparticles (NPs) and their application to the [3+2] cycloaddition of azides with terminal alkynes are reviewed. With respect to the importance of click chemistry, CuO hollow NPs, CuO hollow NPs on acetylene black, water-soluble double-hydrophilic block copolymer (DHBC) nanoreactors and ZnO–CuO hybrid NPs were synthesized. Non-conventional energy sources such as microwaves and ultrasound were also applied to these click reactions, and good catalytic activity with high regioselectivity was observed. CuO hollow NPs on acetylene black can be recycled nine times without any loss of activity, and water-soluble DHBC nanoreactors have been developed for an environmentally friendly process.