Discrepancy between different estimates of the hydrodynamic diameter of polymer-coated iron oxide nanoparticles in solution (original) (raw)
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Materials Science and Engineering: C
Biocompatible ferrofluids based on dextran coated iron oxide nanoparticles were fabricated by conventional co-precipitation method. The experimental results show that the presence of dextran in reaction medium not only causes to the appearance of superparamagnetic behavior but also results in significant suppression in saturation magnetization of dextran coated samples. These results can be attributed to size reduction originated from the role of dextran as a surfactant. Moreover, weight ratio of dextran to magnetic nanoparticles has a remarkable influence on size and magnetic properties of nanoparticles, so that the sample prepared with a higher weight ratio of dextran to nanoparticles has the smaller size and saturation magnetization compare with the other samples. In addition, the ferrofluids contain such nanoparticles have an excellent stability at physiological pH for several months. Furthermore, the biocompatibility studies reveal that surface modification of nanoparticles by dextran dramatically decreases the cytotoxicity of bare nanoparticles and consequently improves their potential application for diagnostic and therapeutic purposes.
Dynamics of Superparamagnetic Iron Oxide Nanoparticles with Various Polymeric Coatings
Materials
In this article, the results of a study of the magnetic dynamics of superparamagnetic iron oxide nanoparticles (SPIONs) with chitosan and polyethylene glycol (PEG) coatings are reported. The materials were prepared by the co-precipitation method and characterized by X-ray diffraction, dynamic light scattering and scanning transmission electron microscopy. It was shown that the cores contain maghemite, and their hydrodynamic diameters vary from 49 nm for PEG-coated to 200 nm for chitosan-coated particles. The magnetic dynamics of the nanoparticles in terms of the function of temperature was studied with magnetic susceptometry and Mössbauer spectroscopy. Their superparamagnetic fluctuations frequencies, determined from the fits of Mössbauer spectra, range from tens to hundreds of megahertz at room temperature and mostly decrease in the applied magnetic field. For water suspensions of nanoparticles, maxima are observed in the absorption part of magnetic susceptibility and they shift to...
Size dependent magnetic properties of iron oxide nanoparticles
Journal of Magnetism and Magnetic Materials, 2003
Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.
International Journal of Molecular Sciences
Carboxymethyl-dextran (CMD)-coated iron oxide nanoparticles (IONs) are of great interest in nanomedicine, especially for applications in drug delivery. To develop a magnetically controlled drug delivery system, many factors must be considered, including the composition, surface properties, size and agglomeration, magnetization, cytocompatibility, and drug activity. This study reveals how the CMD coating thickness can influence these particle properties. ION@CMD are synthesized by co-precipitation. A higher quantity of CMD leads to a thicker coating and a reduced superparamagnetic core size with decreasing magnetization. Above 12.5–25.0 g L−1 of CMD, the particles are colloidally stable. All the particles show hydrodynamic diameters < 100 nm and a good cell viability in contact with smooth muscle cells, fulfilling two of the most critical characteristics of drug delivery systems. New insights into the significant impact of agglomeration on the magnetophoretic behavior are shown. R...
Journal of Magnetism and Magnetic Materials, 2009
Colloidal nanoparticles of Fe 3 O 4 (4 nm) were synthesized by high-temperature hydrolysis of chelated iron (II) and (III) diethylene glycol alkoxide complexes in a solution of the parent alcohol (H 2 DEG) without using capping ligands or surfactants: [Fe(DEG)Cl 2 ] 2-+ 2[Fe(DEG)Cl 3 ] 2-+ 2H 2 O + 2OH -→ Fe 3 O 4 + 3H 2 DEG + 8Cl -The obtained particles were reacted with different small-molecule polydentate ligands, and the resulting adducts were tested for aqueous colloid formation. Both the carboxyl and α-hydroxyl groups of the hydroxyacids are involved in coordination to the nanoparticles' surface. This coordination provides the major contribution to the stability of the ligandcoated nanoparticles against hydrolysis.
Particulate Science and Technology, 2014
We report a simple phase transfer based synthesis route for two novel anisotropic water soluble iron oxide nanoparticle shapes, namely, nanoplates and nanoflowers. The nanoplates and nanoflowers are initially prepared in an organic solvent via a modified ''heat-up'' method. Then, the crystalline nanoparticles are rendered hydrophilic via sonication in the presence of dextran and water. These nanoparticles are highly monodisperse and superparamagnetic at room temperature. High resolution transmission electron microscopy indicates that the iron oxides cores are not affected by the phase transfer. Dextran coating is confirmed by dynamic light scattering, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The obtained dextran coverage was 26 wt% for the nanoplates and 37 wt% for the nanoflowers. The nanoplates and nanoflowers were not only water soluble, but also remained stable at different pH (4-7) and in common aqueous buffer solutions. Thorough characterizations of the nonspherical iron oxide nanoparticles indicate that these particles could be useful for potential biomedical applications and magnetic resonance imaging.
Colloidal Stability and Magnetophoresis of Gold-Coated Iron Oxide Nanorods in Biological Media
The Journal of Physical Chemistry C, 2012
Magnetic iron oxide nanorods are coated with a gold colloid (Fe/Au NRs) to form core−shell particles that combine magnetic and plasmonic properties in a single nanostructure. Three different macromolecules are employed to surface functionalize the nanorod in order to promote colloidal stability of these particles in elevated ionic strength media (∼154 mM NaCl equivalent) that are appropriated for biomedical applications. With a 10 000 molecular weight poly(ethylene glycol) (PEG), the NRs flocculated and sedimented within a few minutes. However, Pluronic F127 or poly(diallyldimethylamonium chloride) (PDDA) coatings yielded stable dispersions for up to 20 h. These NRs exhibit two absorbance peaks at 530 nm and ∼740 nm corresponding to the transverse and longitudinal surface plasmon resonances (SPR). In addition to dynamic light scattering (DLS), spectrophotometry can also be used to monitor dispersion stability because the 530 nm SPR peak shape changes when agglomerates form. The magnetophoretic migration time of these particles, monitored by suspension opacity measurement by light dependent resistor (LDR) under low gradient magnetic separation (LGMS), was prolonged from 1.5 min to ∼8 min after surface functionalization.
Unconventional magnetic behavior of iron-oxide nanoparticles in polymeric matrices
Journal of Applied Physics, 2001
... matrices. [Journal of Applied Physics 90, 1534 (2001)]. AM Testa, S. Foglia, L. Suber, D. Fiorani, Ll. Casas, A. Roig, E. Molins, JM Grenèche, J. Tejada. Abstract. ... Mössbauer effect; other γ-ray spectroscopy. Body. I. INTRODUCTION. Significant ...
In the present study, the influence of the organic stabilizers on the formation of magnetic iron-oxide nanoparticles was investigated. Polyethylene glycol (PEG), dextran (DEX), and chitosan was chosen as biocompatible surface modification agents for obtained magnetic nanoparticles. The structure of the coated Fe3O4 nanoparticles was learned by the X-ray diffraction and Fourier-transform infrared spectroscopic methods. It was explored that the PEG coated magnetic nanoparticles have relatively larger crystallite sizes, which indicate a more ordered crystal structure of these nanoparticles. Furthermore, FT-IR analysis showed that the Fe3O4-PEG system possesses a stronger nanoparticle-stabilizer interaction at the supramolecular level. This study emphasizes the significance of optimizing the surface properties of magnetic nanoparticles when using them in biomedical applications.
Magnetic behaviour of non-interacting colloidal iron oxide nanoparticles in physiological solutions
Crystal Research and Technology, 2015
Magnetic properties of colloidal nanoparticles (NPs) depend on various parameters, such as size, size distribution, interparticle distance, shape, condition of synthesis and stabilizing surfactants. Nowadays, those magnetic nanoparticles (MNPs) are preferably produced in hydrophobic organic solvents, while biomedical applications need hydrophilic properties. Thus, a major challenge is the hydrophilization of the particles, while avoiding destabilization and aggregation. Here we present magnetic characteristics of non-interacting, highly crystalline iron oxide NPs in physiological solutions that are coated with modified polyacrylic acid. The magnetic analysis comprised both static and dynamic magnetic behaviour of 4 nm nanoparticles. The nanoparticles have been further characterized by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX).