A mathematical model of superparamagnetic iron oxide nanoparticle magnetic behavior to guide the design of novel nanomaterials (original) (raw)
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In Situ Analysis of a Bimodal Size Distribution of Superparamagnetic Nanoparticles
Analytical Chemistry, 2009
The dispersed iron oxide nanoparticles of ferrofluids in aqueous solution are difficult to characterize due to their protective polymer coatings. We report on the bimodal size distribution of superparamagnetic iron oxide nanoparticles found in the MRI contrast agent Resovist, which is a representative example of commercial nanoparticlebased pharmaceutical formulations. The radii of the majority of the nanoparticles (>99%) range from 4 to 13 nm (less than 1% of the particles display radii up to 21 nm). The maxima of the size distributions are at 5.0 and 9.9 nm. The analysis was performed with in situ characterization of Resovist via online coupling of asymmetrical flow field-flow fractionation (A4F) with small-angle X-ray scattering (SAXS) using a standard copper X-ray tube as a radiation source. The outlet of the A4F was directly coupled to a flow capillary on the SAXS instrument. SAXS curves of nanoparticle fractions were recorded at 1-min time intervals. We recommend using the A4F-SAXS coupling as a routine method for analysis of dispersed nanoparticles with sizes in the range of 1-100 nm. It allows a fast and quantitative comparison of different batches without the need for sample preparation.
Applied Magnetic Resonance, 2017
With promising applications of superparamagnetic iron oxide nanoparticles (SPIO) in magnetic resonance imaging (MRI) and targeted monitoring of molecular and cellular processes, many different samples of these nanoparticles (NPs) with different compositions synthesized each year. The main challenge in this way is to generate enough contrast that could be traceable on images. In order to compensate for the low quantity of contrast agents in desired sites, surface engineering has to be done to enhance relaxation rates. As many factors such as magnetic field strength can affect relaxation rates of NPs, knowledge of the relation between field strength and relaxation rates is essential to compare results of different fields and choosing an optimum agent for a specific field. In this study, we evaluate the effects of magnetic field strengths of 0.35, 1.5, and 3 T on relaxation rates of PEGylated SPIOs. Longitudinal and transverse relaxation rates of all samples with various concentrations were analyzed quantitatively on appropriate spin-echo sequences. Our results suggest that the increasing of the field strength leads to a marked decrease of longitudinal relaxivity. In the case of transverse relaxivity, all NPs showed an increase between 0.35 and 1.5 T. Upon further increasing the field strength, relaxation rates only slightly increased except for two samples that showed saturation.
Nanomedicine, 2019
To simulate the stability and degradation of superparamagnetic iron oxide nanoparticles (MNP) in vitro as part of their life cycle using complex simulated biological fluids. Materials & methods: A set of 13 MNP with different polymeric or inorganic shell materials was synthesized and characterized regarding stability and degradation of core and shell in simulated biological fluids. Results: All MNP formulations showed excellent stability during storage and in simulated body fluid. In endosomal/lysosomal media the degradation behavior depended on shell characteristics (e.g., charge, acid-base character) and temperature enabling the development of an accelerated stress test protocol. Conclusion: Kinetics of transformations depending on the MNP type could be established to define structure-activity relationships as prediction model for rational particle design.
nano Online, 2018
Superparamagnetic iron oxide nanoparticles (SPIONs) have been identified as a promising material for biomedical applications. These include as contrast agents for medical imaging, drug delivery and/or cancer cell treatment. The nanotoxicological profile of SPIONs has been investigated in different studies and the distribution of SPIONs in the human body has not been fully characterized. The aim of this study was to develop a physiologically-based pharmacokinetic (PBPK) model to predict the pharmacokinetics of SPIONs. The distribution and accumulation of SPIONs in organs were simulated taking into consideration their penetration through capillary walls and their active uptake by specialized macrophages in the liver, spleen and lungs. To estimate the kinetics of SPION uptake, a novel experimental approach using primary macrophages was developed. The murine PBPK model was validated against in vivo pharmacokinetic data, and accurately described accumulation in liver, spleen and lungs. After validation of the murine model, a similar PBPK approach was developed to simulate the distribution of SPIONs in humans. These data demonstrate the utility of PBPK modeling for estimating biodistribution of inorganic nanoparticles and represents an initial platform to provide computational prediction of nanoparticle pharmacokinetics.
ScienceAsia, 2019
Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely studied in biomedical applications such as bioimaging through magnetic resonance imaging and drug delivery. The successful uses of SPIONs depend on nanoparticles stability in biological environment and their interactions with cells. Hence these two factors are crucial for improvement of nanoparticle design in these applications. In this work, SPIONs were synthesized with silica (S-SPIONs) and amine (A-SPIONs) surface modifications providing hydroxyl and amine functionalities, respectively. The colloidal stabilities of SPIONs were evaluated as hydrodynamic size in different biological relevance media. The results showed that bare SPIONs were unstable and highly aggregated when exposed to cell culture media. Coating with silica and amine could effectively stabilized the nanoparticles as evidenced by reduction of hydrodynamic diameters. In addition to surface modification, supplementation of serum proteins to cell culture media also reduced the aggregations. Furthermore, both S-SPIONs and A-SPIONs showed no cytotoxicity effect on human breast cancer cells (MCF-7) with cell viability remained over 80%. Hence this study showed the role of surface modification of bare SPIONs with silica and amine functionalization and serum supplement to stabilize nanoparticle stability in biological environment. These two surface coating SPIONs were not only non-toxic to the cells, but also have surface functionalities that could be further conjugated with desired biomolecules for more specific targeting especially in cancer targeting for diagnosis or therapeutic applications.
Langmuir, 2013
Superparamagnetic microparticles are extensively used in the purification of biomolecules due to the speed and ease of magnetic separation. It is desirable that the microparticles used in biological affinity separations have both high surface area and high magnetic mobility to facilitate a high binding capacity of target biomolecules and their rapid removal from solution, respectively. Scaling laws for conventional spherical superparamagnetic microparticles are such that increasing the microparticle specific surface area results in a significant decrease in the magnetic mobility. More favorable combinations of these key parameters can be found if alternative microparticle morphologies are developed for use in affinity separations. Emulsion-templated self-assembly of iron oxide nanoparticles into microparticles using oil-in-water emulsions was carried out using a modified Couette shear mixer with separate inlet ports for the oil and aqueous phases, enabling high throughput microparticle synthesis. By controlling the dissolved nanoparticle concentration and nanoparticle surface activity at the droplet interfaces, the resulting microparticles were tuned to spherical, dimpled, or crumpled morphologies. The specific binding capacity and magnetic mobility of each type of microparticle were measured by a peroxidase-based colorimetric assay and by their magnetic field-induced motion in a viscous fluid, respectively. Superparamagnetic microparticles with dimpled and crumpled morphologies were found to have higher specific binding capacities compared to spherical microparticles, while maintaining high magnetic field velocities due to their high iron oxide content. Superparamagnetic microparticles with these novel morphologies would make excellent tools for affinity-based bioseparations where binding capacity and magnetic mobility are key factors.
International Journal of Nanomedicine
Ultrasmall superparamagnetic iron oxide (USPIO) particles are maghemite or magnetite nanoparticles currently used as contrast agent in magnetic resonance imaging. The coatings surrounding the USPIO inorganic core play a major role in both the in vitro stability and, over all, USPIO's in vivo fate. Different physicochemical properties such as final size, surface charge and coating density are key factors in this respect. Up to now no precise structure--activity relationship has been described to predict entirely the USPIOs stability, as well as their pharmacokinetics and their safety. This review is focused on both the classical and the latest available techniques allowing a better insight in the magnetic core structure and the organic surface of these particles. Concurrently, this work clearly shows the difficulty to obtain a complete physicochemical characterization of USPIOs particles owing to their small dimensions, reaching the analytical resolution limits of many commercial...