Comparison of theories of anisotropy in transformer oil-based magnetic fluids

The external magnetic field in transformer oil-based magnetic fluids leads to the aggregation of magnetic nanoparticles and formation of clusters. These aggregations are the result of the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs. However, the temperature of magnetic fluids has also very important influence on the structural changes because the mechanism of thermal motion acts against the cluster creation. The acoustic spectroscopy was used to study the anisotropy of transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature. In present the anisotropy of the magnetic fluids can be described by two theories. Taketomi theory assumes the existence of spherical clusters. These clusters form long chains, aligned in a magnetic field direction. Shliomis in his theory supposed that only nanoparticles formed chains. A comparison of the experimental results with the predictions of the Taketomi theory allowed a determination of the cluster radius and the number density of the colloidal particles. The proportions of the acoustic wave energy used for excitation of the translational and rotational motion were determined

Sono-magnetic heating in tumor phantom

There exist various types of hyperthermia therapy such as radiofrequency, infrared, microwave, focused ultrasound or magnetic. Recently, a lot of effort has been put into combining more than one mode of heating into one treatment. The multimodal hyperthermia proves a better alternative in comparison with a single one. In this paper, we show that the application of dual sono-magnetic heating (ultrasound and magnetic together) gives better results than using either of them alone. The advantage of this bimodal treatment lies not only in cumulative heating of target volume (tumor) but also in synergistic interaction between the two mechanisms—the ultrasound sonication can improve the thermal effect of magnetic hyperthermia through the unblocking Brown’s relaxation. Furthermore, the ultrasound and magnetic heating are complementary to each other. The temperature rise caused by ultrasound is fast changing and by magnetic field slow changing. So the parameters of ultrasound can serve as coarse-tuning settings of heating while the parameters of the magnetic field as fine-tuning enabling more precise hyperthermia

Magnetic Nanoparticles for Application in Nanomedicine

This contribution will summarize the information about the ways of synthesizing biocompatible magnetic nanoparticles and complexes containing them and the possibility of their application in nanomedicine at magnetic drug targeting and thermal treatment of diseases by hyperthermia effect. Some procedures of the preparation of biocompatible magnetizable complexes as magnetic nanoparticles, magnetic fluids, some proteins and enzymes covalently bound to the freshly prepared magnetic nanoparticles in the presence of carbodiimide (bovine serum albumin, streptokinase, chymotrypsin, dispase, glucose oxidase), entrapment of magnetic particles into magnetoliposomes and encapsulation of clinically important drug as indomethacin and taxol together with magnetite nanoparticles in biodegradable polymer. We will summarize the results from the study of structural, magnetic and hyperthermic properties of bacterial magnetite nanoparticles i.e. magnetosomes prepared by biomineralization process of magnetotactic bacteria as a promising material for application in nanomedicine

Magnetosomes - Bacterial Magnetic Nanoparticles

The magnetic properties, magneto-optical effects and hyperthermia effect were studied in solution of magnetosomes extracted from cultivated bacteria Magnetospirillum sp. AMB-1. The properties of magnetosomes were changed using different conditions during synthesis and by modification of particles after synthesis by using sonication and ultracentrifugation methods. It was shown that adding a higher amount of Wolfe's vitamin solution (WVS) or ferric quinate (FQ) cause increase of the mean diameter from 47 nm (normal condition) up to 52 nm and 58 nm respectively. Hyperthermic measurements were performed for three types of magnetosome samples: (I) M - not influenced by separation method (long - chains magnetosomes), (II) UM - after centrifugation procedure, and (III) SM - after centrifugation procedure including sonication. The Specific Absorption Rate (SAR) decreased depending on chains shortening and decrease in hysteresis too. The SAR values were 1083, 934 or 463 W/g for the sample M, UM and SM, respectively

Endovascular administration of magnetized nanocarriers targeting brain delivery after stroke

The increasing use of mechanical thrombectomy in stroke management has opened the window to local intraarterial brain delivery of therapeutic agents. In this context, the use of nanomedicine could further improve the delivery of new treatments for specific brain targeting, tracking and guidance. In this study we take advantage of this new endovascular approach to deliver biocompatible poly(D-L-lactic-co-glycolic acid) (PLGA) nanocapsules functionalized with superparamagnetic iron oxide nanoparticles and Cy7.5 for magnetic targeting, magnetic resonance and fluorescent molecular imaging. A complete biodistribution study in naïve (n = 59) and ischemic (n = 51) mice receiving intravenous or intraarterial nanocapsules, with two different magnet devices and imaged from 30 min to 48 h, showed an extraordinary advantage of the intraarterial route for brain delivery with a specific improvement in cortical targeting when using a magnetic device in both control and ischemic conditions. Safety was evaluated in ischemic mice (n = 69) showing no signs of systemic toxicity nor increasing mortality, infarct lesions or hemorrhages. In conclusion, the challenging brain delivery of therapeutic nanomaterials could be efficiently and safely overcome with a controlled endovascular administration and magnetic targeting, which could be considered in the context of endovascular interventions for the delivery of multiple treatments for stroke.We are grateful for the technical assistance received from the Pre-clinical imaging Platform at Vall d’Hebron Institut de Recerca, the Servei RMN at Universitat Autònoma de Barcelona, and the Unitat de Microscopia Òptica Avançada, Facultat de Medicina at the Universitat de Barcelona. This work has been supported under the Euronanomed MAGGBRIS collaborative project by grants from the Spanish Ministry of Science and Innovation (PCIN-2017-090 grant), the Instituto de Salud Carlos III (AC17/00004 with FEDER funds), the Slovak Research and Development Agency under the Contract No.APVV-19-0324 and the Italian Ministry of Health (Ricerca Corrente year 2017 funds); by the Expression of Interest (EoI) for Collaborative Projects on Regenerative Medicine 2019 P-CMR[C]); programs 2017-SGR-1427 and 2017-SGR-765 from the Generalitat de Catalunya; RETICS-INVICTUS PLUS from ISCIII (RD16/0019/0021 with FEDER funds); the ‘Severo Ochoa’ Program for Centers of Excellence in R&D (SEV-2015-0496) and the RYC-2017- 22412 and PID2019-107989RB-I00. A.G has been supported by fellowships from ISCIII (FI17/00073 and MV18/00006), A.R by a visiting-scientist fellowship from ISCIII (BA17/00052) and Y. Z has been supported by the China Scholarship Council (CSC).Peer reviewe