Magnetic resonance imaging of adipose-derived adult stem cells labelled with superparamagnetic iron oxide nanoparticles

The application of mesenchymal stem cells (MSCs) represents a new promising approach for treating neurodegenerative diseases. Recently, considerable attention has been paid to adipose-derived adult MSC (ADAS), thanks to the easy availability of adipose tissue and to the possibility of autologous cells transplantation. Any possible application of therapies based on ADAS in the clinics cannot occur without elucidation of their homing. Superparamagnetic iron-oxide nanoparticles (NPs) can be used to label and track cells in vivo via Magnetic Resonance Imaging (MRI

Evaluation of the synthesis process of SPIONs for MPI with different iron salts with MPS

Tracers play a decisive role for the image quality in the MPI. The gold standard Resovist provides acceptable images, but not all of the iron in the Resovist contributes to signal generation. This results in a much higher amount of iron having to be injected into the organism than would be necessary for imaging. Although iron is one of the essential trace elements, it is toxic in higher doses. Therefore, tracer development must focus equally on improving image quality and reducing iron doses. This paper presents the standard method of co-precipitation with different iron salts. The different anions used have different ionic strengths and thus influence the crystal formation of the superparamagnetic magnetite.   Int. J. Mag. Part. Imag. 6(2), Suppl. 1, 2020, Article ID: 2009070, DOI: 10.18416/IJMPI.2020.200907

Superparamagnetic Iron Oxide Nanoparticles

The direct detection of the spatial distribution of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) as a tracer for Magnetic Particle Imaging (MPI) enables threedimensional functional images with high spatial and temporal resolution. The commercially available tracers have not been developed primarily for MPI. Therefore, they do not sufficiently contribute to the desired image quality. Hence, optimizing the SPIONs during the production process is of interest. A peculiarity of the here presented synthesis method - the alkaline coprecipitation - is that this process takes place under ultrasonic control. The use of ultrasound creates extraordinary reaction conditions through sonochemical phenomena, such as formation, growth and implosive collapse of cavitation bubbles within a liquid. In addition, the ultrasonic waves and the oscillation of the medium improve the mixing process and thus ensure the homogenization during the synthesis. The objective of this study is the variation of ultrasonic frequencies and the type of used dextran as coating material, to provide SPIONs with better performance for MPI and more suitable properties for in vivo application. The focus of the optimization is to increase the magnetite core size while simultaneously reducing the hydrodynamic size. The experiments have shown that both, the ultrasound frequency and the molecular weight of used dextran, influence the properties of the SPIONs

Stability analysis of ferrofluids

Superparamagnetic iron oxides (SPIOs) are used as tracer for the new imaging technique Magnetic Particle Imaging. The stability of ferrofluids for medical application has a great importance, in addition to the particle size. The shell material, which protects the iron core prior from agglomeration and sedimentation, can be degraded by various processes. Another important aspect of stability is the constant performance of magnetisation. Therefore, the measurement of the magnetisation of the particles must be controlled in order to ensure the stability of the samples

Influence of reaction parameters on the synthesis of silica-coated superparamagnetic iron oxide particles

Superparamagnetic iron oxide nanoparticles (SPIONs) are playing an increasingly important role in medical technology. They can serve as tracers for the new imaging modality Magnetic Particle Imaging (MPI), magnetic beats for magnetic cell separation, or for hyperthermia treatment of tumorous tissue. Of particular interest are their unique magnetic properties. These are based on the morphology of a particle core consisting of iron oxide, encased in a biocompatible material. Through the synthesis process, both the size of the core and the nature of the silica coating material can be controlled. The influence of the synthesis parameters on the magnetic and size properties of the SPIONs will be investigated

Optimization of the coprecipitation in the synthesis of SPIONs with rigorize control of process conditions

In this work, superparamagnetic iron oxide nanoparticles were synthesized using an alkaline coprecipitation. Two different bases (NaOH and NH3) were used. Furthermore, the influence of temperature on the properties of the products was investigated. Three different Dextran derivates were used as shell material for the syntheses. The products of the different syntheses were investigated by Magnetic Particle Spectroscopy (MPS) and Photon Correlation Spectroscopy (PCS). The magnetic properties and the hydrodynamic diameter were used as quality criteria of the produced SPIONs. The results of this studies were evaluated and carefully compared

A synthesis apparatus for the continuous flow synthesis of Magnetic Nanoparticles

In magnetic particle imaging, superparamagnetic iron oxide nanoparticles are used as a tracer material. By utilizing the non-linear magnetization of the particles, their concentration in the body can be determined with high spatial and temporal resolution. Some of the important properties of the particles are their core diameter, hydrodynamic diameter, size distribution, and magnetic properties. In order to be able to produce particles with adequate quality and high reproducibility, a prototype of a continuous-flow synthesis apparatus is designed and tested. This research deals with the design and construction of a device that can use the co-precipitation synthesis method to synthesis particles in continuous flow

Contribution of brownian rotation and particle assembly polarisation to the particle response in magnetic particle spectrometry

The spectrometry of super-paramagnetic iron-oxide nanoparticles is a central tool for characterising particles that are used in Magnetic Particle Imaging. In Magnetic Particle Imaging, nanoparticles are excited by a magnetic field and the particle response is measured. Until now, the influence of the trajectory sequence on the dynamic particle relaxation has not been scoped. With a multi-dimensional Magnetic Particle Spectrometer, analysing the behaviour of different trajectories on the particles becomes possible. In this paper, the contribution of Brownian rotation and assembly polarisation on the particle signal is being analysed