Materials with a 1^st order magnetic transition have attracted much attention because of their large magnetocaloric effect, i.e. a large isothermal entropy change (ΔS) induced by a pseudo-static magnetic field. While this material family has hitherto almost solely been studied for the magnetic cooling effects due to the reversibility of ΔS, we have found that the irreversible heating power (i.e. energy loss) could be enhanced dramatically near T_C due to the magnetic phase coexistence associated with the 1^st order magnetic transition. An example of such a unique effect was observed in LaFe_11.57Si_1.43H_1.75 with its upper T_C of 319 K. The spontaneous magnetization (M_s) shows a very abrupt decrease from 110 Am²/kg at 316 K to zero at 319 K. This large M_s immediately below T_C along with the enhanced irreversibility of the hysteresis curve result in a specific absorption rate as large as 0.5 kW/g under a field of 8.8 kA/m at 279 kHz. This value is nearly an order of magnitude larger than that observed under the same condition for conventional iron oxide-based materials. Moreover, the large heating effect is self-regulated at the 1^st order T_C (319 K) which resides in the ideal temperature range for hyperthermia treatment of cancerous cells. This proof-of-concept study shows that the extraordinary heating effect near the 1^st order Curie point opens up a novel alloy design strategy for large, self-regulated induction heating.

We have shown that theranostic properties of the magnetic nanostructures (MNS) can be significantly enhanced by tuning their core composition and length of surface coating. In this study, we have synthesized monodisperse metal ferrite (MFe₂O₄) nanoparticles of size 8 nm using thermal decomposition method and functionalized with nitrodopamine conjugated polyethylene glycol (NDOPA-PEG). The composition was controlled by tuning the stoichiometry of MFe₂O₄ nanoparticles (where M = Fe, Mn, Zn, Zn_xMn_1-x) while the length of surface coating was tuned by changing the molecular weight of PEG (200 to 2000). The PEGylated MFe₂O₄ nanoparticles demonstrated high colloidal stability across a wide pH range (6-10) and cell culture medium and the cell viability studies showed no cytotoxicity. After optimization, the r₂ relaxivity of 552 mM^-1s^-1 and specific absorption rate of 355 W/g was obtained. Our results suggest that both core as well as surface coating are important factors to take into consideration during the design of theranostic MNS. When coupled with the desired targeting agents, these ultra-stable MNS have great potential in targeted theranostic applications.

Magnetic nanoparticles could help to improve clinical practice in the treatment of cancer, most probably in synergy with other conventional treatments [1]. There already exist methods to obtain magnetic nanoparticles with the appropriate properties to be used in diagnosis and therapy but these properties need to be optimized to avoid its alteration after intravenous injection due to aggregation in lysosomes inside cells or accumulation in tissues [2, 3].
In this work we will show the effect of different characteristics of the magnetic colloids, such as particle size and size distribution, colloidal properties of the aqueous suspensions, such as hydrodynamic size and surface modification, and magnetic properties that depend on the synthesis route, on their MRI relaxivity and heating capacity. Magnetic nanoparticles biodistribution and its transformation over time are also affected by these parameters and can be tracked by AC magnetic susceptibility measurements. This technique allows identifying and quantifying magnetic nanoparticles in tissues, differentiating them from other endogenous species such as the ferritin iron cores [4].
References
[1] M. Colombo, et al, Chem. Soc. Rev., 41, 4306, 2012.
[2] Y. Luengo, et al, Nanoscale, 5, 11428, 2013; A. Ruiz, et al, Nanoscale, 5, 11400, 2013.
[3] L. Gutiérrez, et al, Dalton Transactions 2015 (in press).
[4] R. Mejías, et al, Journal of Controlled Release 171, 225, 2013; L. Gutiérrez, et al, Phys. Chem. Chem. Phys., 16, 4456-4464, 2014;
Acknowledgements
This work was partially supported by projects from the Spanish Ministry of Economy and Competitiveness (MAT2011-23641), EU-FP7 MULTIFUN project (246479), EU-FP7 NANOMAG (604448), and AXA Research Fund (L.G.).

The side-effects of non-steroid anti-inflammatory drugs used in the management of osteoarthritis have elicited considerable research interest in the alternative treatment modalities including hyperthermia treatment of degenerated knee joint. This treatment may be extended to orthopaedic applications for economic and ergonomic purposes. Here, we report the use of Polyvinylidene fluoride (PVDF) encapsulated Chromium doped Iron (III) Oxide (CFO) nanocomposite for hyperthermia treatment of osteoarthritic knee joint. CFO was synthesised by sol-gel processing route and encapsulated in PVDF matrix using acetic acid media. X-Ray Diffraction (XRD) and Rietveld analysis confirmed the formation of CFO. Room temperature Vibrating Sample Magnetometry (VSM) and Differential Thermogravimetric Analysis - Differential Scanning Calorimetry (DTA-DSC) were used to analyse the magnetic and thermal properties of the encapsulated composites respectively. Scanning Electron Microscopy (SEM) was used to study the morphology of the composites. MTT assay confirmed the non-toxic nature of the nanocomposite. 3D finite element method (FEM) simulation of toroid and spherical geometry of the PVDF-CFO was carried out and the effects of volume percentage, geometry, implantable positions were studied using this method. The implications of the results for the development of implantable devices for the localized treatment of osteoarthritis have also been discussed.

Abstract: In the current study, an in vitro blood-brain barrier (BBB) model was developed using a triple co-culture of immortalized murine brain endothelial cells, immortalized murine astrocytes and mouse brain vascular pericytes. By measuring the permeability coefficients and TEER values [1], we examined the tightness of the cell monolayer and confirmed that this method has enabled brain endothelial cells to cross-talk with neighboring cells and therefore improved the integrity of the in vitro BBB model. After the model was successfully established and confirmed, permeability of several nanoliposomes was determined using this model.
Materials and Methods: The collagen coated nanoliposome and PEG coated nanoliposome were prepared and encapsulate with iron oxide [2]. SEM was used to characterize their surface morphology and TEM was used to assess the iron oxide inner core diameter. For the in vitro blood- brain barrier model, pericytes were cultured and seeded on the bottom side of the collagen-coated Transwell® inserts and astrocytes were seeded on the bottom of the 24-well plates separately. After 12 hours of adhesion, murine brain endothelial cells were seeded onto the upper side of the inserts and the inserts would then be placed in the 24-well plates containing astrocytes. The model would be evaluated and confirmed using TEER and FITC-Dextran transport [3]. Then, the model was used to test the permeability of the various nanoparticles. The model would be exposed to nanoparticles for 2 hours. After 2 hours, an iron assay kit was used to determine the iron concentration that passed through the model. Each experiment was conducted in triplicate and repeated at least three times.
Results and Discussion: Previous results showed that the highest permeability was obtained from collagen coated nanoparticles. This result suggests that nanoliposomes coated with collagen had better permeability across the BBB than nanoliposomes coated with PEG.
Conclusions: Through such experiments, magnetic nanomaterials (such as magnetic nanoliposome) suitable for MRI use which are less permeable to the blood brain barrier to avoid neural tissue toxicity and magnetic nanoliposomes suitable for brain drug delivery since they were more permeable to the BBB were created.
References: [1] Pardridge WM. Molecular Trojan horses for BBB drug delivery. Curr Opin Pharmacol. 2006; 6:494-500. [2] Krishnamoorthy G, et al. Collagen Coated Nanoliposome as a Targeted and Controlled Drug Delivery System. AIP Conf. Proc, 2010; 1276, 163. [3] Bennett J, et al. Blood-brain barrier disruption and enhanced vascular permeability in the multiple sclerosis model EAE. J Neuroimmunol. 2010; 229:180-191.

The properties of magnetic nanoparticles vary dramatically with size, and reproducibly controlling size is critical for practical applications. This is particularly true when moving into clinical settings, where regulatory approval requires demonstrated reproducibility in efficacy that can only be achieved with excellent size control. We present a general method for size control in the synthesis of nanoparticles by establishing steady state growth through the continuous, controlled addition of precursor. The steady state growth regime is characterized by a constant concentration of unreacted precursor as well as a uniform rate of growth in particle volume. This approach, which we have termed the “Extended LaMer Mechanism” of growth allows reproducibility in particle size from batch to batch, as well as prediction of size produced later in a reaction by monitoring early stages of growth. We have demonstrated this method using an important and challenging synthetic system, magnetite nanoparticles. To facilitate this reaction, we also devised a reproducible method for synthesizing an iron oleate precursor that can be used without purification. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy&’s National Nuclear Security Administration under contract DE-AC04-94AL85000

Magnetic nanoparticles are unique among nanomaterials due to our ability to control their translation and rotation, and actuate thermal release, through the application of magnetic field gradients and time-varying magnetic fields. Furthermore, because of their biocompability and the fact that magnetic fields penetrate through the body, magnetic nanoparticles possess tremendous potential for biomedical applications. In this talk I will discuss our recent work aimed at understanding the response of magnetic nanoparticles to time-varying magnetic fields and engineering of magnetic nanoparticles for biomedical applications, such as thermal cancer therapy, magnetic particle imaging, and probing the mechanical properties of biological environments.

While magnetic nanomaterials have already been used in clinics for contrast enhancement in magnetic resonance imaging (MRI) [1], there has been no clinical approval for a drug delivery system containing such nanoparticles, yet. Magnetic nanoparticles currently investigated for their possible application in biomedicine are predominantly different crystalline polymorphs of iron oxides. For small enough crystal sizes, iron oxides exhibit the so-called “superparamagnetic” behavior, a feature combining high magnetization with very low coercive forces. Such superparamagnetic nanoparticles show great potential in therapeutic applications due to their ability to transform the energy of an alternating magnetic field to thermal energy in what is often called magnetic fluid hyperthermia [2]. These particles dissipate thermal energy by magnetic relaxation through the Brownian and Neel mechanisms. Therefore, aqueous suspensions at relatively higher nanoparticle concentrations (g/L), the so-called “ferrofluids”, also increase their temperature in the presence of an alternating magnetic field [3]. In this work, a composite multi-scale structure consisting of the biopolymer alginate, functional nanoparticles and a model drug is fabricated and analyzed. We examine the potential of flame-made SiO₂-coated Fe₂O₃ nanoparticles [4] as the stimuli-responsive material in the multi-scale composite structure. We perform detailed physicochemical and magnetic characterization on the hybrid alginate hydrogel beads and evaluate their potential in magnetic fluid hyperthermia and enhanced biomolecule release in the presence of an external AMF. The possibility to externally stimulate drug release will open up new possibilities in intelligent, on-demand drug administration.
References
[1] A. Singh, S. K. Sahoo, Drug Discov. Today, 19, 474-481 (2014).
[2] A. Jordan, R. Scholz, P. Wust, H. Fahling, R. Felix, J. Magn. Magn. Mater., 201, 413-419 (1999).
[3] G. A. Sotiriou, M. A. Visbal-Onufrak, A. Teleki, E. J. Juan, A. M. Hirt, S. E. Pratsinis, C. Rinaldi, Chem. Mater., 25, 4603-4612 (2013).
[4] A. Teleki, M. Suter, P. R. Kidambi, O. Ergeneman, F. Krumeich, B. J. Nelson, S. E. Pratsinis, Chem. Mater., 21, 2094-2100 (2009)

An intricate spatial and temporal control of magnetic microbeads during their motion is important for the successful transport of labelled chemical and biological species in microfluidic cells. Especially monodisperse beads with a superparamagnetic particle-loaded shell and a diameter of a few micrometers act as a model system for biological cell manipulation.
We present a detailed study, comprising bead entrapment and its phase-delayed continuous motion by periodic rotation of external magnetic fields, a frequency modulated local displacement, and thus a reduced bead velocity. The experimental data is underlined by a