Fabrication of Colloidal Stable, Thermosensitive, and Biocompatible Magnetite Nanoparticles and Study of Their Reversible Agglomeration in Aqueous Milieu (original) (raw)
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Surface modification of magnetite nanoparticles for biomedical applications
Journal of Magnetism and Magnetic Materials, 2009
The preparation of magnetite nanoparticles with narrow size distributions using poly(ethylene glycol) (PEG-COOH) or carboxymethyl dextran (CMDx) chains covalently attached to the particle surface using carbodiimide chemistry is described. Particles were synthesized by thermal decomposition and modified with 3-aminopropyl trimethoxysilane (APS) to render particles with reactive amine groups (-NH 2 ) on their surface. Amines were then reacted with carboxyl groups in PEG-COOH or CMDx using carbodiimide chemistry in water. The size and stability of the functionalized magnetic nanoparticles was studied as a function of pH and ionic strength using dynamic light scattering and zeta potential measurements.
Synthesis of Magnetite/Amphiphilic Polymer Composite Nanoparticles as Potential Theragnostic Agents
Journal of Nanoscience and Nanotechnology, 2012
This study describes the synthesis of magnetite/amphiphilic polymer composite nanoparticles that can be potentially used simultaneously for cancer diagnosis and therapy. The synthesis method was a one-shot process wherein magnetite nanoparticles were mixed with core-crosslinked amphiphilic polymer (CCAP) nanoparticles, prepared using a copolymer of a urethane acrylate nonionomer (UAN) and a urethane acrylate anionomer (UAA). The CCAP nanoparticles had a hydrophobic core and a hydrophilic exterior with both PEG segments and carboxylic acid groups, wherein the magnetite nanoparticles were coordinated and stabilized. According to DLS data, the ratio of UAN to UAA and the ratio of magnetite to polymer are keys to controlling the size and thus, the stability of the composite nanoparticles. The magnetic measurement indicated that the composite nanoparticles had superparamagnetic properties and high saturation magnetization. The preliminary magnetic resonance imaging showed that the particles produced an enhanced image even when their concentration was as low as 80 g/ml.
Synthesis and characterization of stable dicarboxylic pegylated magnetite nanoparticles
Materials Letters, 2013
The coating of implantable nano-or micro-objects with polyethylene glycol (PEG) enhances its biocompatibility and biodistribution. Herein, we describe a new protocol that enhances and maintains MNPs stability in biological media, simulating multiple conditions to which they would be subjected in the human body. Magnetite nanoparticles (MNPs) prepared via a facile way at room temperature by coprecipitation reaction, were coated with dicarboxylic polyethylene glycol (DCPEG) via covalent bonds. The surface of the nanoparticles was first coated with 3-aminopropyl trimethoxysilane by a silanization reaction and then linked with DCPEG of different molecular weight (Mw ¼ 5000, 10,000 and 20,000 g mol −1). The uncoated magnetite nanoparticles, with an average size of 20 nm, exhibited superparamagnetism, high saturation magnetization and a negative surface charge (with a zeta potential value of −40 mV). Increase of Mw enhances the colloidal stability of MNPs and makes them more suitable to tolerate high salt concentrations (1M NaCl) and wide pH (from 5.5 to 12) and temperature ranges (24 1C to 46 1C). The results indicate that magnetite nanoparticles coated with DCPEG with Mw ¼20,000 have improved properties over their counterparts, making them our best choice for biomedical studies.
Journal of Research Updates in Polymer Science, 2015
In this article, a microemulsion method for preparation of magnetite composite polymer nanoparticles of Fe3O4@poly(styrene-methacrylic acid) (MNP@PSMA) crosslinked with1,6-hexanediol diacrylate (HDD) insitu with carboxyl functionality on the surface has been reported. Structure and morphology of the nanoparticles was studied by Fourier Transform Infrared spctroscopy (FTIR), X ray Diffraction (XRD), Thermal Gravimetric Analyser (TGA), Vibrating Sample Magnetometer (VSM) and Transmission Electron Microscopy (TEM). VSM studies confirmed saturation magnetization of 20.0 emu/g in an external magnetic field. Nanoparticles formed were of 30 nm in diameter with narrow size distribution and mosaic structure providing a large surface area useful for application in bioseparation. Experimental results of covalent coupling of composite nanoparticles indicated maximum protein binding capacity of 350 mg bovine serum albumin (BSA) per gram.
One-Pot Reaction to Synthesize Biocompatible Magnetite Nanoparticles
Advanced Materials, 2005
Magnetic nanoparticles have shown great potential in both in-vitro and in-vivo biomedical applications. [1] So far, most invitro applications have focused on the ultrasensitive detection and separation of viruses, oligonucleotides, DNA, and proteins, while the in-vivo applications have been concentrated on cell tagging, tracking and imaging, targeted drug delivery, as well as hyperthermia treatment of cancers. For some in-vivo applications, efficient internalization of magnetic nanoparticles into specific cells is often required, which can be realized by receptor-mediated endocytosis. For example, Weissleder's group conducted magnetic resonance (MR) cell tracking by using an antitransferrin receptor monoclonal antibody (mAb) to conjugate with dextran-coated MION-46L iron oxide nanoparticles to induce receptor-mediated endocytosis. [6a] In their later experiments, they also succeeded in ferrying magnetic nanoparticles modified with a short HIV-Tat peptide into progenitor cells. [6b] The efficient internalization of magnetic nanoparticles makes it possible to visualize cells by MRI (magnetic resonance imaging) techniques at the single-cell level in vivo. [6b] For most in-vivo applications, the efficient internalization of nanoparticles into specific cells needs to overcome nonspecific targeting (plasma protein adsorption) and short blood half-lives. The latter is strongly related to the recognition and phagocytosis of magnetic nanoparticles by macrophages. [9a] One strategy to increase the blood half-life of nanoparticles and to decrease the non-specific interactions with plasma proteins is to modify the magnetic nanoparticles with poly(ethylene glycol) (PEG), since PEG is a typical non-toxic, non-immunogenic, non-antigenic, and protein-resistant polymer. Weissleder and his coworkers have demonstrated that coating MION (monocrystalline iron oxide nanocompounds) with methoxy[poly(ethylene glycol)]-O-succinyl succinate can dramatically increase the blood half-life to 4 h. [6c] Following a similar strategy, Zhang and his colleagues modified magnetic nanoparticles with functional PEG silane and investigated the internalization of the PEG-covered nanoparticles into mouse macrophage cells. Their experimental results revealed that the amount of PEG-modified nanoparticles taken up into the mouse macrophage cells is much lower than that of unmodified nanoparticles. [9a] However, most surface modifications by PEG and its derivatives were achieved by sophisticated post-preparative procedures. [6c,9b] Here, we report a novel one-pot preparative approach for synthesizing magnetic nanocrystals covalently covered by monocarboxyl-terminated poly(ethylene glycol) (MPEG-COOH). MRI experiments performed on living rats demonstrate that the MPEG-modified magnetite nanoparticles have very good biocompatibility and can potentially be used as MRI contrast agents.
Biomaterials, 2005
In the current study, amine surface modified iron-oxide nanoparticles of 6 nm diameter without polymer coating were fabricated in an aqueous solution by organic acid modification as an adherent following chemical coprecipitation. Structure and the superparamagnetic property of magnetite nanoparticles were characterized by selected area electron diffraction (SAED) and superconducting quantum interference measurement device (SQUID). X-ray photoelectron spectrometer (XPS) and zeta potential measurements revealed cationic surface mostly decorated with terminal -NH 3 + . This feature enables them to function as a magnetic carrier for nucleotides via electrostatic interaction. In addition, Fe 3 O 4 /trypsin conjugates with well-preserved functional activity was demonstrated. The nanoparticles displayed excellent in vitro biocompatibility. The NMR and the in vitro MRI measurements showed significantly reduced water proton relaxation times of both T 1 and T 2 . Significantly reduced T 2 and T 2 *-weighted signal intensity were observed in a 1.5 T clinical MR imager. In vivo imaging contrast effect showed a fast and prolonged inverse contrast effect in the liver that lasted for more than 1 week. In addition, it was found that the spherical Fe 3 O 4 assembled as rod-like configuration through an aging process in aqueous solution at room temperature. Interestingly, TEM observation of the liver tissue revealed the rod-like shape but not the spherical-type nanoparticles being taken up by the Kupffer cells 120 h after tail vein infusion. Combining these results, we have demonstrated the potential applications of the newly synthesized magnetite nanoparticles in a broad spectrum of biomedical applications. r
Preparation of glycopolymer-coated magnetite nanoparticles for hyperthermia treatment
Journal of Polymer Science Part A: Polymer Chemistry, 2012
In this article, magnetite nanoparticles (MNPs) coated with glycopolymer bearing glucose moieties were designed with optimal structural, colloidal, and magnetic properties for biomedical applications. MNPs with an average size of 17 6 2 nm were synthesized by thermal decomposition process and then their surfaces were modified with active vinyl groups. Two different monomers were immobilized onto the surfaces: dopamine methacrylamide, a monomer with properties inspired on mussels adhesive capacity, or unprotected glycomonomer, 2-{[(D-glucosamin-2N-yl)carbonyl]-oxy}ethyl methacrylate. Afterward, the glycomonomer were polymerized at the interface of both vinyl functionalized MNPs by conventional radical polymerization. The resultant hybrid NPs were water dispersible presenting good stability in aqueous solution for long time periods. Moreover, the high density of carbohydrates at the surface of the magnetic NPs could confer targeting properties to the system as demonstrated by studies of their binding interactions with lectins, where the binding activity is higher as the glycopolymer content augments. The magnetic and magneto-thermal properties of the synthesized hybrid NPs were evaluated. The magnetization curves reveal superparamagnetic features at 300 K, with high values of saturation magnetization. Furthermore, the hybrid glycoparticles show suitable heat dissipation power when exposed to alternating magnetic field conditions.
Towards a versatile platform based on magnetic nanoparticles for in vivo applications
Bulletin of Materials Science, 2006
Magnetic nanoparticles have attracted wide attention because of their usefulness as contrast agents for magnetic resonance imaging (MRI) or colloidal mediators for cancer magnetic hyperthermia. This paper examines these in vivo applications through an understanding of the problems involved and the current and future possibilities for resolving them. A special emphasis is made on magnetic nanoparticle requirements from a physical viewpoint, the factors affecting their biodistribution and the solutions envisaged for enhancing their half-life in the blood compartment and targeting tumour cells. Then, our synthesis strategies are presented and focused on covalent platforms based on maghemite and dextran and capable to be tailorderivatized by surface molecular chemistry. The opportunity of taking advantage of temperature-dependence of magnetic properties of some complex oxides for controlling the in vivo temperature is also discussed.
Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media
Magnetite nanoparticles (MNPs) were prepared by alkaline hydrolysis of Fe(II) and Fe(III) chlorides. Adsorption of polyacrylic acid (PAA) on MNPs was measured at pH=6.5±0.3 and I=0.01 M (NaCl) to find the optimal PAA amount for MNP stabilization under physiological conditions. We detected an H-bond formation between magnetite surface groups and PAA by ATR-FTIR measurements, but bonds of metal ion-carboxylate complexes, generally cited in literature, were not identified at the given pH and ionic strength. The dependence of the electrokinetic potential and the aggregation state on the amount of added PAA at various pHs was measured by electrophoretic mobility and dynamic light-scattering methods. The electrokinetic potential of the naked MNPs was low at near physiological pH, but PAA adsorption overcharged the particles. Highly negatively charged, well-stabilized carboxylated MNPs formed via adsorption of PAA in an amount of approximately ten times of that necessary to compensate the original positive charge of the magnetite. Coagulation kinetics experiments revealed gradual enhancement of salt tolerance at physiological pH from ~ 0.001 M at no added PAA up to ~0.5 M at 1.12 mmol/g PAA. The PAA-coated MNPs exert no substantial effect on the proliferation of malignant (HeLa) or non-cancerous fibroblast cells (MRC-5) as determined by means of MTT assays.
Despite the large efforts to prepare super paramagnetic iron oxide nanoparticles (MNPs) for biomedical applications, the number of FDA or EMA approved formulations is few. It is not known commonly that the approved formulations in many instances have already been withdrawn or discontinued by the producers; at present, hardly any approved formulations are produced and marketed. Literature survey reveals that there is a lack for a commonly accepted physicochemical practice in designing and qualifying formulations before they enter in vitro and in vivo biological testing. Such a standard procedure would exclude inadequate formulations from clinical trials thus improving their outcome. Here we