magnetic iron oxide nanoparticles coated ..
Synthesis and magnetic properties of gold coated iron oxide nanoparticles.
Synthesis and magnetic properties ..
The research on superparamagnetic iron oxide nanoparticles (SPIONs) has been growing exponentially over the last several years. The field continues to drive in the direction of biomedical applications, especially molecular therapeutics by exploiting the immense qualities of SPIONs . This includes the distinctive controllable properties such as size, shape, magnetism, crystallinity and flexibility in fabricating multifunctional SPIONs with fluorescence, targeting ligands, drugs etc, thanks to the advancements in the syntheses and functionalization techniques developed hitherto. There are some excellent synthetic methods in prior arts on the formation of superparamagnetic magnetite (Fe3O4) and maghemite (γ-Fe2O3) SPIONs, with size control, narrow distribution, water solubility and surface functionalization [-]. The co-precipitation method is a conventional synthetic paradigm where Fe(II) and Fe(III) salts are co-precipitated in a basic solution in the presence of coating materials such as polymer or dextran (or its derivatives). Although the resulted iron oxide nanoparticles (NPs) are larger in size (ca. 100 nm) and partially crystalline, the particles are readily water soluble where their surfaces are directly functionalized. Alternatively, thermal decomposition method using precursors such as Fe(CO)5, Fe(Stearate)2, with high boiling solvents (octadecene, benzyl ether) and surfactants/ligands (oleic acid, oleylamine) can be used to synthesize smaller sized hydrophobic SPIONs (5-10 nm). In order to impart the SPIONs with water solubility for biomedical applications, water-oil microemulsion method can be employed as a reaction medium for coating a hydrophilic ligand (e.g. silica, peptides) on the hydrophobic surface.
We report a simple process to generate iron oxide coated gold nanorods. Gold nanorods, synthesized by our three-step seed mediated protocol, were coated with a layer of polymer, poly(sodium 4-styrenesulfonate). The negatively charged polymer on the nanorod surface electrostatically attracted a mixture of aqueous iron(II) and iron(III) ions. Base-mediated coprecipitation of iron salts was used to form uniform coatings of iron oxide nanoparticles onto the surface of gold nanorods. The magnetic properties were studied using a superconducting quantum interference device (SQUID) magnetometer, which indicated superparamagnetic behavior of the composites. These iron oxide coated gold nanorods were studied for macroscopic magnetic manipulation and were found to be weakly magnetic. For comparison, premade iron oxide nanoparticles, attached to gold nanorods by electrostatic interactions, were also studied. Although control over uniform coating of the nanorods was difficult to achieve, magnetic manipulation was improved in the latter case. The products of both synthetic methods were monitored by UV−vis spectroscopy, zeta potential measurements, and transmission electron microscopy. X-ray photoelectron spectroscopy was used to determine the oxidation state of iron in the gold nanorod−iron oxide composites, which is consistent with Fe2O3 rather than Fe3O4. The simple method of iron oxide coating is general and applicable to different nanoparticles, and it enables magnetic field-assisted ordering of assemblies of nanoparticles for different applications.
We report on synthesis, structural, and magnetic ..
()We report on synthesis, structural, and magnetic properties ofchemically synthesized iron oxide (Fe3O4) andFe3O4@Au core-shell nanoparticles.
115. Ge S, Shi X, Sun K, Li C, Baker JR, Banaszak Holl MM andOrr BG. A facile hydrothermal synthesis of iron oxide nanoparticles with tunable magnetic properties. 2009;13:13593-9
Gold-coated iron nanoparticles: a novel magnetic …
This paper describes a sol−gel approach for the coating of superparamagnetic iron oxide nanoparticles with uniform shells of amorphous silica. The coating process has been successfully applied to particles contained in a commercial ferrofluid (e.g., the EMG 304 of Ferrofluidics) and those synthesized through a wet chemical process. The thickness of silica coating could be conveniently controlled in the range of 2−100 nm by changing the concentration of the sol−gel solution. Fluorescent dyes, for example, 7-(dimethylamino)-4-methylcoumarin-3-isothiocyanate (DACITC) and tetramethylrhodamine-5-isothiocyanate (5-TRITC), have also been incorporated into the silica shells by covalently coupling these organic compounds with the sol−gel precursor. These multifunctional nanoparticles are potentially useful in a number of areas because they can be simultaneously manipulated with an externally applied magnetic field and characterized in situ using conventional fluorescence microscopy.
19. Narain R, Gonzales M, Hoffman AS, Stayton PS, Krishnan KM. Synthesis of monodisperse biotinylated p(NIPAAM)-coated iron oxide magnetic nanoparticles and their bioconjugation to streptavidin. 2007;23:6299-6304
Synthesis and properties of magnetic-optical ..
Magnetic iron oxide nanoparticles for ..
Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications
Gold coated magnetic nanoparticles ..
As the particles were gradually coated by gold, the black iron oxide ..
Hybrid gold-iron oxide nanoparticles as a …
10/05/2016 · Gold coated magnetic nanoparticles: from preparation to ..
synthesis and physicochemical properties ..
The idea behind the multilayer concept is that a unique medical platform could have various properties from the detection to the cure of diseases. For example, the magnetic nanoparticle (MNP) surface can be engineered to achieve layering structure, to produce multi-functionalized nanoparticles for the prevention, diagnosis and treatment of diseases. Layering of iron oxide nanoparticles will generate functional SPIONs formed by three main components: (1) an iron oxide core functioning as MRI contrast agent, (2) a biocompatible coating and (3) a therapeutic coating targeted with a pharmacogenomics biomarker (Figure ).[-]
Magnetic Iron Oxide Nanoparticles: Synthesis and …
Hydrophilic SPIONs for biological application usually consist of an iron oxide core and a surface coating. On one hand, synthesis methods of the iron oxide core, stabilizer and reaction parameters have significant effects on the size and magnetic properties of SPIONs [, -]. On the other hand, surface coating materials, functionalization materials and surface engineering methods significantly affect ultimate size in living fluid, biocompatibility, cell internalization and duration in cells [, , , ]. Therefore, to prepare ideal SPIONs, major factors such as core synthesis, surface coating and functional materials, and surface engineering methods should be carefully considered.
Surface functionalized magnetic iron oxide nanoparticles ..
Although many synthetic routes have been developed for the preparation of iron oxide core with tunable shape, size and magnetization, several challenges remain for the naked SPIONs in terms of stem cell labeling, including: (i) poor water solubility and tendency of aggregation due to large surface/volume ratio; (ii) low cellular uptake efficiency; (iii) potential toxicity. To address these problems, the most straightforward and effective method seems to be coating the iron oxide core by a layer. The nature of the surface coatings and modification methods determine the physical and biologic properties such as the overall size, surface charge, coating density, toxicity and degradability, which finally affect the fate of SPIONPs in the cells [, ]. This following section focuses on the currently used surface modification materials (e.g. PLL, PEI, chitosan, PEG, citric acid and so on) and methods (e.g. coating, post-synthesis coatings including blending, polymerization, ligand exchange) for the SPIONs applied for stem cell labeling and tracking. The influence of these factors on labeling efficiency and biocompatibility is also discussed.
the magnetic iron oxide NPs coated with gold
5. Ge S, Shi X, Sun K, Li C, Uher C, Baker JR, Banaszak MM, Orr BG. Facile hydrothermal synthesis of iron oxide nanoparticles with tunable magnetic properties. 2009;113:13593-99
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