Lab and Pilot-Scale Synthesis of MxOm@SiC Core-Shell Nanoparticles.

The addition of light ceramic particles to bulk technological materials as reinforcement to improve their mechanical properties has attracted increasing interest in the last years. The metal matrix composites obtained using nanoparticles have been reported to exhibit an improvement of their properties due to the decrease in the size of the ceramic additives to the nanoscale. Additionally, important effects such as the dispersion of the nanoparticles, wettability, and low reactivity can be controlled by the modification of the nanoparticles' surface. In this work, we present the preparation of core-shell MxOm@SiC nanoparticles with different shell compositions. The accurate and reproducible preparation is developed both at the lab and pilot scale. The synthesis of these core-shell nanoparticles and their scale-up production are fundamental steps for their industrial use as additives in metal matrix composites and alloys. Powder X-ray diffraction and energy dispersive X-ray (EDX) coupled with scanning transmission electron microscopy (STEM) are used to corroborate the formation of the core-shell systems, whereas line scan-EDX analysis allows measuring the average shell thickness.

Combining magnetic hyperthermia and dual T1/T2 MR imaging using highly versatile iron oxide nanoparticles.

Magnetic hyperthermia and magnetic resonance imaging (MRI) are two of the most important biomedical applications of magnetic nanoparticles (MNPs). However, the design of MNPs with good heating performance for hyperthermia and dual T1/T2 contrast for MRI remains a considerable challenge. In this work, ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) are synthesized through a simple one-step methodology. A post-synthetic purification strategy has been implemented in order to separate discrete nanoparticles from aggregates and unstable nanoparticles, leading to USPIONs that preserve chemical and colloidal stability for extended periods of time. The optimized nanoparticles exhibit high saturation magnetization and show good heating efficiency in magnetic hyperthermia experiments. Remarkably, the evaluation of the USPIONs as MRI contrast agents revealed that the nanoparticles are also able to provide significant dual T1/T2 signal enhancement. These promising results demonstrate that USPIONs are excellent candidates for the development of theranostic nanodevices with potential application in both hyperthermia and dual T1/T2 MR imaging.

Influence of medium viscosity and intracellular environment on the magnetization of superparamagnetic nanoparticles in silk fibroin solutions and 3T3 mouse fibroblast cell cultures.

Biomedical applications based on the magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) may be altered by the mechanical attachment or cellular uptake of these nanoparticles. When nanoparticles interact with living cells, they are captured and internalized into intracellular compartments. Consequently, the magnetic behavior of the nanoparticles is modified. In this paper, we investigated the change in the magnetic response of 14 nm magnetic nanoparticles (Fe3O4) in different solutions, both as a stable liquid suspension (one of them mimicking the cellular cytoplasm) and when associated with cells. The field-dependent magnetization curves from inert fluids and cell cultures were determined by using an alternating gradient magnetometer, MicroMagTM 2900. The equipment was adapted to measure liquid samples because it was originally designed only for solids. In order to achieve this goal, custom sample holders were manufactured. Likewise, the nuclear magnetic relaxation dispersion profiles for the inert fluid were also measured by fast field cycling nuclear magnetic relaxation relaxometry. The results show that SPION magnetization in inert fluids was affected by the carrier liquid viscosity and the concentration. In cell cultures, the mechanical attachment or confinement of the SPIONs inside the cells accounted for the change in the dynamic magnetic behavior of the nanoparticles. Nevertheless, the magnetization value in the cell cultures was slightly lower than that of the fluid simulating the viscosity of cytoplasm, suggesting that magnetization loss was not only due to medium viscosity but also to a reduction in the mechanical degrees of freedom of SPIONs rotation and translation inside cells. The findings presented here provide information on the loss of magnetic properties when nanoparticles are suspended in viscous fluids or internalized in cells. This information could be exploited to improve biomedical applications based on magnetic properties such as magnetic hyperthermia, contrast agents and drug delivery.

Carbon-11 radiolabelling of organosulfur compounds: (11) C synthesis of the progesterone receptor agonist tanaproget.

Herein a new (11) C radiolabelling strategy for the fast and efficient synthesis of thioureas and related derivatives using the novel synthon, (11) CS2 , is reported. This approach has enabled the facile labelling of a potent progesterone receptor (PR) agonist, [(11) C]Tanaproget, by the intramolecular reaction of the acyclic aminohydroxyl precursor with (11) CS2 , which has potential applications as a positron emission tomography radioligand for cancer imaging.