Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water‐in‐oil microemulsion systems (ME‐MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME‐MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME‐MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X‐ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1‐MION and ME 2‐MION) obtained have a size range 7–10 nm. The protein and ME‐MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT‐IR); the presence of three peaks at 2970, 2910 and 2870 cm^?1 respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS‐PAGE. CONCLUSION: The ME‐MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. Copyright © 2011 Society of Chemical Industry     

Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment

Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON^LA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON^LA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON^LA-BSA changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature T_max in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.     

Enhanced Magnetic Hyperthermia of Magnetoferritin through Synthesis at Elevated Temperature

Iron oxide nanoparticles have attracted a great deal of research interest in recent years for magnetic hyperthermia therapy owing to their biocompatibility and superior thermal conversion efficiency. Magnetoferritin is a type of biomimetic superparamagnetic iron oxide nanoparticle in a ferritin cage with good monodispersity, biocompatibility, and natural hydrophilicity. However, the magnetic hyperthermic efficiency of this kind of nanoparticle is limited by the small size of the mineral core as well as its low synthesis temperature. Here, we synthesized a novel magnetoferritin particle by using a recombinant ferritin from the hyperthermophilic archaeon Pyrococcus furiosus as a template with high iron atom loading of 9517 under a designated temperature of 90 °C. Compared with the magnetoferritins synthesized at 45 and 65 °C, the one synthesized at 90 °C displays a larger average magnetite and/or maghemite core size of 10.3 nm. This yields an increased saturation magnetization of up to 49.6 emu g⁻¹ and an enhanced specific absorption rate (SAR) of 805.3 W g⁻¹ in an alternating magnetic field of 485.7 kHz and 49 kA m⁻¹. The maximum intrinsic loss power (ILP) value is 1.36 nHm² kg⁻¹. These results provide new insights into the biomimetic synthesis of magnetoferritins with enhanced hyperthermic efficiency and demonstrate the potential application of magnetoferritin in the magnetic hyperthermia of tumors.     

Fabrication and characterization of zinc oxide nanoparticle coated magnetic iron oxide: Effect of S-layers adsorption on surface of oxide

Mixed zinc oxide nanoparticle coated magnetic iron oxide has been prepared by a sol–gel and co-precipitation routes. Magnetic iron oxide nanoparticles were synthesized by co-precipitation of ferric and ferrous ions with ammonia, and then zinc oxide was coated onto the surface of magnetic iron oxide by hydrolysis of zinc precursors. As a result, zinc oxide coated magnetic iron oxide nanoparticles with an average size of 68 nm were obtained. The crystalline bacterial cell surface layer)S-layer (used in this study was isolated from Lactobacillus helveticus ATCC 12046. The S-layer was adsorbed onto the surface of zinc oxide nanoparticle coated magnetic iron oxide. The nanoparticles were analyzed by X-ray powder diffractometry (XRD), infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were used to characterize the structural and the chemical features of the nanocomposites. The infrared spectra indicate that the S-layer-nanoparticle interaction occurs. This novel nanoparticle showed admirable potential in adsorption of S-layers on the surface of oxides for drug delivery.     

Novel Microwave-Assisted Synthesis of Renewable-Resource Based Carbon-Magnetite Nanocomposites

Abstract

Magnetic carbon-iron oxide nanoparticles have been synthesized using tannin, a renewable resource material, in combination with a microwave-based thermolytic process without the addition of any inert or reducing gas during the synthesis. The predominant iron oxide species present in these particles has been determined by XRD and FT-IR to be magnetite (Fe₃O₄). These iron oxide nanoparticles are embedded within a carbon matrix in small clusters generally ≤100 nm in size. The resulting powder is approximately 48% (w/w) magnetite, and has been characterized by magnetic susceptibility and SQUID analysis.     

Synthesis of Organic Dye-Impregnated Silica Shell-Coated Iron Oxide Nanoparticles by a New Method

A new method for preparing magnetic iron oxide nanoparticles coated by organic dye-doped silica shell was developed in this article. Iron oxide nanoparticles were first coated with dye-impregnated silica shell by the hydrolysis of hexadecyltrimethoxysilane (HTMOS) which produced a hydrophobic core for the entrapment of organic dye molecules. Then, the particles were coated with a hydrophilic shell by the hydrolysis of tetraethylorthosilicate (TEOS), which enabled water dispersal of the resulting nanoparticles. The final product was characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and vibration sample magnetometer. All the characterization results proved the final samples possessed magnetic and fluorescent properties simultaneously. And this new multifunctional nanomaterial possessed high photostability and minimal dye leakage.     

Synthesis and characterization of a magnetic hybrid material consisting of iron oxide in a carboxymethyl cellulose matrix

A magnetic hybrid material (MHM), consisting of iron‐oxide nanoparticles (?4 nm) embedded in sodium carboxymethyl cellulose (Na‐CMC) matrix was synthesized. The MHM synthesis process was performed in two stages. First, a precursor hybrid material (Fe(II)‐CMC) was synthesized from two aqueous solutions: Na‐CMC solution and FeCl₂ solution. In the second stage, the precursor hybrid material was treated with H₂O₂ under alkaline conditions to obtain the MHM. The results obtained from X‐ray diffraction show that the crystalline structure of iron oxide into MHM corresponds to maghemite or magnetite phase. Conversely, the results obtained from Fourier transform infrared (FTIR) spectroscopy reveal that the polymeric matrix (Na‐CMC) preserves its chemical structure into the MHM. Furthermore, in FTIR spectra are identified two characteristic bands at 570 and 477 cm^?1 which can be associated to maghemite phase. Images obtained by high resolution transmission electron microscopy and bright field scanning transmission electron microscope show that iron‐oxide nanoparticles are embedded in the Na‐CMC. Magnetic properties were measured at room and low temperature using a quantum design MPMS SQUID‐VSM magnetometer. Diagrams of magnetization versus temperature show that iron‐oxide nanoparticles embedded in Na‐CMC have a superparamagnetic‐like behavior. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

蒙脱石和聚乙烯吡咯烷酮界面作用对零价铁纳米颗粒制备及其性能调控的影响与机理

以蒙脱石为载体,水溶性聚合物聚乙烯吡咯烷酮（PVP）为稳定剂,通过硼氢化钠化学液相还原高铁离子制备了零价铁纳米粒子。采用扫描电镜、透射电镜、X射线衍射分析、X射线光电子能谱分析等手段对所得铁粒子进行了表征。结果表明,所得铁粒子大致呈球状形貌,尺寸较均匀,平均粒径约为34nm,在蒙脱石颗粒外表面分散良好。该铁粒子内核为零价铁,表面包覆铁氧化物外壳,外壳厚度保持3nm左右,有效抑制了零价铁内核的深度氧化。PVP自身及其与蒙脱石颗粒通过界面作用形成的层离结构均可对铁粒子起到分散作用,使所得铁粒子较之蒙脱石和PVP未参与制备的铁粒子粒径减小、分散程度提高。     

Optimization of Synthesis Parameters for Mesoporous Shell Formation on Magnetic Nanocores and Their Application as Nanocarriers for Docetaxel Cancer Drug

In this work, Fe₃O₄@SiO₂ nanoparticles were coated with mesoporous silica shell by S⁻N⁺I⁻ pathway by using anionic surfactant (S⁻) and co-structure directing agent (N⁺). The role of co-structure directing agent (CSDA) is to assist the electrostatic interaction between negatively charged silica layers and the negatively charged surfactant molecules. Prior to the mesoporous shell formation step, magnetic cores were coated with a dense silica layer to prevent iron oxide cores from leaching into the mother system under any acidic circumstances. However, it was found that both dense and mesoporous coating parameters affect the textural properties of the produced mesoporous silica shell (i.e., surface area, pore volume and shell thickness). The synthesized Fe₃O₄@SiO₂@m-SiO₂ (MCMSS) nanoparticles have been characterized by low-angle X-ray diffraction, transmission electron microscopy (TEM), and N₂ adsorption-desorption analysis, and magnetic properties. The synthesized particles had dense and mesoporous silica shells of 8–37 nm and 26–50 nm, respectively. Furthermore, MCMSS possessed surface area of ca. 259–621 m²·g⁻¹, and pore volume of ca. 0.216–0.443 cc·g⁻¹. MCMSS showed docetaxcel cancer drug storage capacity of 25–33 w/w% and possessed control release from their mesochannels which suggest them as proper nanocarriers for docetaxcel molecules.     

Core/shell polymethyl methacrylate/polyethyleneimine particles incorporating large amounts of iron oxide nanoparticles prepared by emulsifier-free emulsion polymerization

A facile synthetic route for the preparation of magnetic poly(methyl methacrylate) (PMMA) core/polyethyleneimine (PEI) shell colloidal particles, possessing high saturation magnetization is reported. Bilayer oleic acid-stabilized iron oxide nanoparticles (bIOs) were designed to have both favorable encapsulation of iron oxide nanoparticles and interaction with protonated amine groups of PEI. The prepared particles had diameter ranging from 180 to 207 nm with narrow size distribution and displayed highly positive surface charges up to +47 mV. TEM revealed that the well-defined bIOs were successfully encapsulated inside the polymer core–shell colloids. Thermogravimetric analysis and magnetization study indicated that these colloidal particles had the magnetic material up to 80 wt % loading and exhibited superparamagnetic property with high saturation magnetization. Thus, they could be potentially useful in various applications, including magnetic separation, medical diagnostics, or drug delivery.     

His-tagged protein immobilization on cationic ferrite magnetic nanoparticles

Magnetic nanoparticles have been applied in various fields because of their interesting magnetic properties. Immobilization on magnetic nanoparticles is a very important step in functionalizing them. We examined protein immobilization efficiency using interactions between his-tagged enhanced green fluorescence protein and affordable cationic ferrite magnetic nanoparticles for the first time. Four types of ferrite magnetic nanoparticles were verified: cobalt iron oxide, copper iron oxide, nickel iron oxide, and iron (III) oxide as negative controls. Among the four ferrite magnetic nanoparticles, copper ferrite magnetic nanoparticle was confirmed to have the highest immobilization efficiency at 3.0 mg proteins per gram ferrite magnetic nanoparticle and 78% of total enhanced green fluorescence protein. In addition, the maximum binding efficiency was determined for copper ferrite magnetic nanoparticle. Consequently, this newly verified his-tag-immobilizing capacity of copper ferrite magnetic nanoparticle could provide a facile, capable, and promising strategy for immobilizing his-tagged proteins or peptides with high purity for biosensors, magnetic separation, or diagnostics.     

Magnetic properties of superparamagnetic nanoparticles loaded into silicon nanotubes

In this work, the magnetic properties of silicon nanotubes (SiNTs) filled with Fe₃O₄ nanoparticles (NPs) are investigated. SiNTs with different wall thicknesses of 10 and 70 nm and an inner diameter of approximately 50 nm are prepared and filled with superparamagnetic iron oxide nanoparticles of 4 and 10 nm in diameter. The infiltration process of the NPs into the tubes and dependence on the wall-thickness is described. Furthermore, data from magnetization measurements of the nanocomposite systems are analyzed in terms of iron oxide nanoparticle size dependence. Such biocompatible nanocomposites have potential merit in the field of magnetically guided drug delivery vehicles.

PACS

61.46.Fg; 62.23.Pq; 75.75.-c; 75.20.-g     

Influence of a graphite shell on the thermal and electromagnetic characteristics of FeNi nanoparticles

Graphite-coated FeNi alloy nanoparticles have been prepared by a modified arc-discharge method in an alcohol atmosphere and have been characterized by means of X-ray diffraction, energy dispersive spectroscopy, transmission electron microscopy, Raman spectroscopy, thermal gravimetric analysis and scanning differential thermal analysis. The results show that the nanoparticles have a core/shell structure, with FeNi alloy as core and graphite layers as shell. Compared with FeNi nanoparticles with an oxide shell, the graphite shell restricts the growth of the FeNi nanoparticles, which leads to lower saturation magnetization and higher natural-resonance frequency. Due to the enhancement of the thermal stability by the graphite shell and its oxidation protection, the graphite-coated FeNi nanoparticles are stable in air below 240 °C. The electromagnetic characteristics of the graphite-coated FeNi nanoparticles have been studied in the 2-18 GHz range. The graphite shell dramatically improves the magnetic/dielectric loss and the attenuation constant in the 9-18 GHz range through the enhancement of the electrical resistivity and the protection of the FeNi cores, leading to enhanced microwave-absorption properties in this range.     

Fe3O4@mesoporouspolyaniline: A Highly Efficient and Magnetically Separable Catalyst for Cross‐Coupling of Aryl Chlorides and Phenols

A high surface, magnetic Fe₃O₄@mesoporouspolyaniline core‐shell nanocomposite was synthesized from magnetic iron oxide (Fe₃O₄) nanoparticles and mesoporouspolyaniline (mPANI). The novel porous magnetic Fe₃O₄ was obtained by solvothermal method under sealed pressure reactor at high temperature to achieve high surface area. The mesoporouspolyaniline shell was synthesized by in situ surface polymerization onto porous magnetic Fe₃O₄ in the presence of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), as a linker and structure‐directing agent, through ‘blackberry nanostructures’ assembly. The material composition, stoichiometric ratio and reaction conditions play vital roles in the synthesis of these nanostructures as confirmed by variety of characterization techniques. The role of the mesoporouspolyaniline shell is to stabilize the porous magnetic Fe₃O₄ nanoparticles, and provide direct access to the core Fe₃O₄ nanoparticles. The catalytic activity of magnetic Fe₃O₄@mesoporousPANI nanocomposite was evaluated in the cross‐coupling of aryl chlorides and phenols.     

An alternative route for the synthesis of silicon nanowires via porous anodic alumina masks

Amorphous Si nanowires have been directly synthesized by a thermal processing of Si substrates. This method involves the deposition of an anodic aluminum oxide mask on a crystalline Si (100) substrate. Fe, Au, and Pt thin films with thicknesses of ca. 30 nm deposited on the anodic aluminum oxide-Si substrates have been used as catalysts. During the thermal treatment of the samples, thin films of the metal catalysts are transformed in small nanoparticles incorporated within the pore structure of the anodic aluminum oxide mask, directly in contact with the Si substrate. These homogeneously distributed metal nanoparticles are responsible for the growth of Si nanowires with regular diameter by a simple heating process at 800°C in an Ar-H₂ atmosphere and without an additional Si source. The synthesized Si nanowires have been characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman.     

Nanocrystalline Iron Particles Synthesized without Chilling by Chemical Vapor Condensation

Iron nanoparticles were synthesized without a chilling device in a condensation system of gases vaporized from iron pentacarbonyls as starting precursors. The size distribution of the synthesized iron particles was wider, namely, ranging from 10 to 100 nm, than that of the particles rapidly cooled on the surface of a chiller. The oxide shell thicknesses were analyzed quantitatively in synthesized powders, along with their microstructures and magnetic properties.Original English Text Copyright © 2005 by Fizika i Khimiya Stekla, Lee, Jang, D. Kim, Tolochko, B. Kim.This article was submitted by the authors in English.     

Preparation and magnetic behavior of carbon-encapsulated cobalt and nickel nanoparticles from starch

Carbon-encapsulated cobalt and nickel nanoparticles with core/shell structure have been successfully synthesized with maize-derived starch as carbon source and metal nitrate as metal precursors in flowing hydrogen. The as-prepared M@Cs materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction technique (XRD) and vibrating sample magnetometer (VSM). The effects of the metal precursors on the structure and the size of the M@Cs materials were investigated, and the magnetic properties of the M@Cs materials were measured. The results show that the structure and the size of the M@Cs materials are different in terms of the different metal precursors. The Co@Cs materials are made of the fcc-Co core and the graphitic carbon shell, of which the core diameter is in a range of 20–35 nm, while the Ni@Cs materials are composed of fcc-Ni core and the amorphous carbon shell, of which the core diameter ranges from 30 to 50 nm. The hysteresis loops of the as-made M@Cs materials show that some of the nanoparticles are in a superparamagnetic state at room temperature. A mechanism is proposed to explain the growth process of the M@Cs materials. It is believed that the starch with the helical structure is responsible for the formation of the M@Cs materials featuring the core/shell structure.     

An In Vitro Experimental Approach to Study Magnetically Targeted Release of Methotrexate From Superparamagnetic Starch Nanocarriers

In the field of drug delivery, magnetic nanoparticles have great potential to modernize anticancer therapy. In the present study iron oxides containing superparamagnetic starch nanoparticles were prepared by emulsion crosslinking method. The anticancer drug methotrexate was used for loading onto the magnetic starch nanoparticles and released drug was spectrophotometrically monitored at physiological pH (7.4) under application of a modulating magnetic field. The spectroscopic techniques such as FTIR, TEM, X-ray diffraction, and vibrating sample magnetometer (VSEM) studies were used to characterize the magnetic starch nanocarriers. The influence of various experimental parameters such as pH and temperature of the release media, percent drug loading, chemical compositions of nanocarriers, and applied magnetic field were investigated on the drug release profiles of synthesized magnetic starch nanoparticles. The nanoparticles were also evaluated for cytotoxicity and in vitro blood compatibility.     

Facile synthesis of folate-conjugated magnetic/fluorescent bifunctional microspheres

In this paper, we investigated the functional imaging properties of magnetic microspheres composed of magnetic core and CdTe quantum dots in the silica shell functionalized with folic acid (FA). The preparation procedure included the preparation of chitosan-coated Fe₃O₄ nanoparticles (CS-coated Fe₃O₄ NPs) prepared by a one-pot solvothermal method, the reaction between carboxylic and amino groups under activation of NHS and EDC in order to obtain the CdTe-CS-coated Fe₃O₄ NPs, and finally the growth of SiO₂ shell vent the photoluminescence (PL) quenching via a Stöber method (Fe₃O₄-CdTe@SiO₂). Moreover, in order to have a specific targeting capacity, the magnetic and fluorescent bifunctional microspheres were synthesized by bonding of SiO₂ shell with FA molecules via amide reaction (Fe₃O₄-CdTe@SiO₂-FA). The morphology, size, chemical components, and magnetic property of as-prepared composite nanoparticles were characterized by ultraviolet-visible spectroscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM), respectively. The results show that the magnetic and fluorescent bifunctional microspheres have strong luminescent which will be employed for immuno-labeling and fluorescent imaging of HeLa cells.