A versatile non-fouling multi-step flow reactor platform: demonstration for partial oxidation synthesis of iron oxide nanoparticles

In the last decade flow reactors for material synthesis were firmly established, demonstrating advantageous operating conditions, reproducible and scalable production via continuous operation, as well as high-throughput screening of synthetic conditions. Reactor fouling, however, often restricts flow chemistry and the common fouling prevention via segmented flow comes at the cost of inflexibility. Often, the difficulty of feeding reagents into liquid segments (droplets or slugs) constrains flow syntheses using segmented flow to simple synthetic protocols with a single reagent addition step prior or during segmentation. Hence, the translation of fouling prone syntheses requiring multiple reagent addition steps into flow remains challenging. This work presents a modular flow reactor platform overcoming this bottleneck by fully exploiting the potential of three-phase (gas–liquid–liquid) segmented flow to supply reagents after segmentation, hence facilitating fouling free multi-step flow syntheses. The reactor design and materials selection address the operation challenges inherent to gas–liquid–liquid flow and reagent addition into segments allowing for a wide range of flow rates, flow ratios, temperatures, and use of continuous phases (no perfluorinated solvents needed). This “Lego®-like” reactor platform comprises elements for three-phase segmentation and sequential reagent addition into fluid segments, as well as temperature-controlled residence time modules that offer the flexibility required to translate even complex nanomaterial synthesis protocols to flow. To demonstrate the platform's versatility, we chose a fouling prone multi-step synthesis, i.e., a water-based partial oxidation synthesis of iron oxide nanoparticles. This synthesis required I) the precipitation of ferrous hydroxides, II) the addition of an oxidation agent, III) a temperature treatment to initiate magnetite/maghemite formation, and IV) the addition of citric acid to increase the colloidal stability. The platform facilitated the synthesis of colloidally stable magnetic nanoparticles reproducibly at well-controlled synthetic conditions and prevented fouling using heptane as continuous phase. The biocompatible particles showed excellent heating abilities in alternating magnetic fields (ILP values >3 nH m2 kgFe−1), hence, their potential for magnetic hyperthermia cancer treatment. The platform allowed for long term operation, as well as screening of synthetic conditions to tune particle properties. This was demonstrated via the addition of tetraethylenepentamine, confirming its potential to control particle morphology. Such a versatile reactor platform makes it possible to translate even complex syntheses into flow, opening up new opportunities for material synthesis

Quantification of Lipoprotein Uptake in Vivo Using Magnetic Particle Imaging and Spectroscopy

Lipids are a major source of energy for most tissues, and lipid uptake and storage is therefore crucial for energy homeostasis. So far, quantification of lipid uptake in vivo has primarily relied on radioactive isotope labeling, exposing human subjects or experimental animals to ionizing radiation. Here, we describe the quantification of in vivo uptake of chylomicrons, the primary carriers of dietary lipids, in metabolically active tissues using magnetic particle imaging (MPI) and magnetic particle spectroscopy (MPS). We show that loading artificial chylomicrons (ACM) with iron oxide nanoparticles (IONPs) enables rapid and highly sensitive post hoc detection of lipid uptake in situ using MPS. Importantly, by utilizing highly magnetic Zn-doped iron oxide nanoparticles (ZnMNPs), we generated ACM with MPI tracer properties superseding the current gold-standard, Resovist, enabling quantification of lipid uptake from whole-animal scans. We focused on brown adipose tissue (BAT), which dissipates heat and can consume a large part of nutrient lipids, as a model for tightly regulated and inducible lipid uptake. High BAT activity in humans correlates with leanness and improved cardiometabolic health. However, the lack of nonradioactive imaging techniques is an important hurdle for the development of BAT-centered therapies for metabolic diseases such as obesity and type 2 diabetes. Comparison of MPI measurements with iron quantification by inductively coupled plasma mass spectrometry revealed that MPI rivals the performance of this highly sensitive technique. Our results represent radioactivity-free quantification of lipid uptake in metabolically active tissues such as BAT

Whither magnetic hyperthermia? A tentative roadmap

The scientific community has made great efforts in advancing magnetic hyperthermia for the last two decades after going through a sizeable research lapse from its establishment. All the progress made in various topics ranging from nanoparticle synthesis to biocompatibilization and in vivo testing have been seeking to push the forefront towards some new clinical trials. As many, they did not go at the expected pace. Today, fruitful international cooperation and the wisdom gain after a careful analysis of the lessons learned from seminal clinical trials allow us to have a future with better guarantees for a more definitive takeoff of this genuine nanotherapy against cancer. Deliberately giving prominence to a number of critical aspects, this opinion review offers a blend of state-of-the-art hints and glimpses into the future of the therapy, considering the expected evolution of science and technology behind magnetic hyperthermia.status: publishe

A plasmonic multi-logic gate platform based on sequence-specific binding of estrogen receptors and gold nanorods

10.1039/c6nr07569jNanoscale84819973-1997

Fine-tuning of gold nanorod dimensions and plasmonic properties using the Hofmeister effects

10.1039/c5tc02426aJournal of Materials Chemistry C4153-6

Superior magnetodielectric properties of CoZnNd ferrites/GNPs composite materials for potential applications

This research explores the effect of graphene nanoplatelets (GNPs) on structural, electrical, magnetic and dielectric properties along with surface morphology of CoZnNd ferrites (CZNF), synthesized through sol-gel auto combustion route. The results exhibited that CZNF particles were dispersed on GNPs, which modified the structural and electromagnetic characteristics of CZNF. Moreover, SEM micrographs revealed the reduction in agglomeration with inclusion of GNPs. Additionally, resistivity was increased in the ferro region and decreased in the para region with rising temperature. TCR for CZNF/2.5 wt %GNPs composite was recorded as −3.49% at 371 K. Excellent magnetodielectric properties were observed for CZNF/2.5 wt %GNPs composite, i.e. Ms = 141.76 emu/g and Hc = 81.2 Oe along with minimum Tan δm and skin depth. On the basis of studied parameters, CZNF/2.5 wt %GNPs composite is appropriate for high frequency micro wave shielding applications, inductors, filters, bolometers and switching devices

Improving the structural and transport properties of cadmium ferrites with the addition of cerium for high frequency applications

Due to their outstanding properties, low cost, and environmental friendliness, mixed transition metal oxides are frequently used in various applications. In this study, Ce3+ doped CdFe2O4 powder samples were prepared through the co-precipitation process. A peak shift was observed towards a lower 2 θ angle with the substitution of Ce3+ at their lattice site and the lattice constant has a maximum value for the x = 0.06 sample with the crystallite size of 34 nm. Moreover, for x = 0.06 sample, the resistivity was found in the order of 106 Ω cm and the dielectric tangent loss had a smaller value. The electrical and dielectric analysis of the as-prepared x = 0.06 sample indicate that it is the best for high-frequency applications