Magnetic hyperthermia with ε-Fe2O3 nanoparticles

Biocompatibility restrictions have limited the use of magnetic nanoparticles for magnetic hyperthermia therapy to iron oxides, namely magnetite (Fe3O4) and maghemite (γ-Fe2O3). However, there is yet another magnetic iron oxide phase that has not been considered so far, in spite of its unique magnetic properties: ε-Fe2O3. Indeed, whereas Fe3O4 and γ-Fe2O3 have a relatively low magnetic coercivity, ε-Fe2O3 exhibits a giant coercivity. In this report, the heating power of ε-Fe2O3 nanoparticles in comparison with γ-Fe2O3 nanoparticles of similar size (∼20 nm) was measured in a wide range of field frequencies and amplitudes, in uncoated and polymer-coated samples. It was found that ε-Fe2O3 nanoparticles primarily heat in the low-frequency regime (20–100 kHz) in media whose viscosity is similar to that of cell cytoplasm. In contrast, γ-Fe2O3 nanoparticles heat more effectively in the high frequency range (400–900 kHz). Cell culture experiments exhibited no toxicity in a wide range of nanoparticle concentrations and a high internalization rate. In conclusion, the performance of ε-Fe2O3 nanoparticles is slightly inferior to that of γ-Fe2O3 nanoparticles in human magnetic hyperthermia applications. However, these ε-Fe2O3 nanoparticles open the way for switchable magnetic heating owing to their distinct response to frequency.This work was supported by European Union's Horizon 2020 FET Open program [Grants no: 801305 and 829162] Spanish Ministry of Science Innovation and Universities [Grant no: PGC2018_095795_B_I00] and Diputación General de Aragón [E11/17R]. Authors would like to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza. This work was developed within the scope of the projects CoolPoint P2020-PTDC-CTMNAN-4511-2014 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement.We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Magnetic tracer-particle tracking in a fluid dynamically down-scaled bubbling fluidized bed

A method for 3-dimensional (3D) magnetic tracer particle tracking in a fluid dynamically downscaled fluidized bed is presented. The method applies Anisotropic Magneto Resistive (AMR) sensors to track a magnetic tracer particle in the form of an NdFeB-based permanent magnet. The fluid dynamically downscaled bed has a cross-section of 0.17x0.17 m2 and is operated at ambient conditions with bronze powder as bulk solids and the tracer particle corresponding to a fuel particle. After up-scaling the bed corresponds to a 0.85x0.85 m2 bed of fuel ash or silica sand operated with air at 900\ub0C using anthracite coal as a fuel. Thus, the method provides continuous tracking of the tracer particle trajectory which, combined with the fluid dynamic scaling yields quantitative information applicable to the study of fuel mixing in large-scale fluidized-bed processes operating under hot conditions. Application of the method represents a significant step forward compared to other experimental studies which are limited to qualitative interpretations; performed in 2D units and in cold 3D units which are not fluid dynamically scaled.It is shown that the AMR sensor system is able to work with the (non-magnetic) bronze powder resulting from the fluid dynamical downscaling, i.e. overcoming the limitation in signal penetration which prevents tracking of radioactive objects in such dense media. Thus, successful application of the AMR method for continuous 3D object tracking in a fluid dynamically downscaled unit is demonstrated for the first time. The measurement system provides both translational and rotational data, unleashing possibilities also as validation tool of CFD models. The preliminary results show a spatial resolution in the order of 1 mm, while temporal resolution is in the order of milliseconds

Simulated and measured piezoelectric energy harvesting of dynamic load in tires

From 2007 in US and from 2022 in EU it is mandatory to use TPMS monitoring in new cars. Sensors mounted in tires require a continuous power supply, which currently only is from batteries. Piezoelectric energy harvesting is a promising technology to harvest energy from tire movement and deformation to prolong usage of batteries and even avoid them inside tires. This study presents a simpler method to simultaneous model the tire deformation and piezoelectric harvester performance by using a new simulation approach - dynamic bending zone. For this, angular and initial velocities were used for rolling motion, while angled polarization was introduced in the model for the piezoelectric material to generate correct voltage from tire deformation. We combined this numerical simulation in COMSOL Multiphysics with real-life measurements of electrical output of a piezoelectric energy harvester that was mounted onto a tire. This modelling approach allowed for 10 times decrease in simulation time as well as simpler investigation of systems parameters influencing the output power. By using experimental data, the simulation could be fine-tuned for material properties and for easier extrapolation of tire deformation with output harvested energy from simulations done at low velocity to the high velocity experimental data.This work has received funding from ECSEL JU-2020-1-IA grant ‘Energy ECS - Smart and secure energy solutions for future mobility’ (grant agreement No 101007247).</p

Development of a Sensitive Induction-Based Magnetic Nanoparticle Biodetection Method.

We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hz⁻10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10-5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM

Nanorheological studies of xanthan/water solutions using magnetic nanoparticles

We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration

Development of a Sensitive Induction-Based Magnetic Nanoparticle Biodetection Method.

We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hz⁻10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10-5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM

Effective particle magnetic moment of multi-core particles

\u3cp\u3eIn this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems - BNF Starch from Micromod with a median particle diameter of 100 nm and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm.\u3c/p\u3