Synthesis and characterization of heat-stabilized albumin magnetic microspheres

Human serum albumin magnetic microspheres containing 30% iron oxide particles were synthesized by a heat-stabilization process. The average diameter, the size distribution and the morphology were characterized by scanning electron microscopy, atomic force microscopy and transmission electron microscopy. The distribution of the iron oxide nanoparticles within the microspheres was confirmed by the contrast obtained in the morphology by backscattered electron imaging in scanning electron microscopy. Energy-dispersive X-ray spectroscopy showed the presence of iron in the microspheres. The cabbage like surface structure in some of the microspheres obtained in scanning electron microscopy can be better understood by atomic force microscopy. This peculiar surface structure in the microsphere may be due to the cross-linking in the protein molecule by heat. The amount of iron oxide in the microsphere was analyzed by atomic absorption spectroscopy. The magnetic properties of the particles were measured in a superconducting quantum interference device magnetometer. Received: 12 September 2000 Accepted: 5 February 2001     

氧化铁磁性纳米粒子的表面配体交换及相转移

以苯甲醇为单一溶剂, 通过常压、高温热解乙酰丙酮铁, 制备了尺寸单分散的四氧化三铁磁性纳米粒子. 采用透射电镜(TEM), X射线衍射(XRD), 动态光散射(DLS)等方法对粒子形貌和结构进行了表征. 利用傅里叶变换红外(FT-IR)光谱和热重分析(TGA)研究了所制备纳米粒子的表面化学, 结果表明稳定四氧化三铁粒子的是苯甲酸分子, 且表面覆盖度小于20%. 所制备的磁性纳米粒子可以在室温下方便地进行表面配体交换, 从而为氧化铁磁性纳米粒子的功能化提供新的途径.     

Mesoporous silica-magnetite nanocomposite: facile synthesis route for application in hyperthermia

The synthesis of nanostructured magnetic materials has been intensively researched because of their large field of applications as magnetic carriers in drug targeting, hyperthermia in tumor treatment, among others. Much effort has been invested in magnetic nanoparticles for bioapplications. However, as these nanoparticles present high specific surface area, unprotected nanoparticles can easily form aggregates and react with oxygen in the air. They can also rapidly biodegrade when directly exposed to biological systems. In this context, we have explored the possibility of synthesizing a mesoporous SiO₂–Fe₃O₄ nanocomposite and its AC magnetic-field-induced heating properties. The magnetite nanocomposite was obtained by impregnation of an iron precursor into a silica framework. The proposed method involves the preparation of an iron oxide precursor in ethanol and the subsequent impregnation of SBA-15 mesoporous hexagonal silica. Iron oxide was formed inside the porous structure, thus producing the magnetic device. The nanocomposite was characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), N₂ adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Measurements of AC magnetic-field-induced heating properties of the obtained nanocomposite, both of the solid form and in aqueous solution, under different applied magnetic fields showed that it is suitable as a hyperthermia agent for biological applications.     

Fe3O4磁性纳米粒子-氧化石墨烯复合材料的可控制备及结构与性能表征

首先利用高温分解法制备了粒径为18 nm的Fe₃O₄磁性纳米粒子, 并进行羧基化修饰, 然后与聚乙烯亚胺(PEI)化学修饰的氧化石墨烯进行交联反应, 得到磁功能化的氧化石墨烯(MGO)复合材料. 研究了氧化石墨烯片上的磁性纳米粒子的可控负载及其对复合材料磁性能的影响. 利用透射电子显微镜(TEM), 原子力显微镜(AFM), X射线衍射(XRD), 傅里叶变换红外(FT-IR)光谱, 热重分析(TGA), 振荡样品磁强计(VSM)等手段对MGO复合材料的形貌, 结构和磁性能进行了表征. 结果表明, 我们发展的MGO复合材料的制备方法具有简单、可控的优点, 所制备的MGO复合材料具有较高的超顺磁性. 该类磁性氧化石墨烯复合材料有望在磁靶向药物、基因输运、磁共振造影以及磁介导的生物分离和去除环境污染物等领域获得广泛的应用.     

Double emulsion droplets as microreactors for synthesis of magnetic macroporous polymer beads

An easy method is presented to fabricate monodisperse magnetic macroporous polymer beads（MMPBs）. Waterin-oil high internal phase emulsion（HIPE） is prepared by emulsifying aqueous iron ions solution in an oil phase containing monomers. The HIPE is introduced into a simple microfluidic device to fabricate monodisperse（water-in-oil）-in-water double emulsion droplets. The droplets serve as microreactors to synthesize Fe3O4 nanoparticles and are on-line polymerized to form MMPBs. The prepared MMPBs display uniform size, interconnected porous structure, superparamagnetic behavior and uniform distribution of Fe3O4 in polymer matrix. The MMPBs are characterized by scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（FTIR）, X-ray diffraction（XRD）, transmission electron microscopy（TEM）, vibrating sample magnetometry（VSM）. We believe that this method is a universal technique in preparing macroporous nanocomposite beads.     

Sonochemical synthesis of stable hydrosol of Fe3O4 nanoparticles

The sonolysis of an aqueous solution of Fe(CO)(5) in the presence of sodium dodecyl sulfate leads to the formation of a stable hydrosol of amorphous Fe(3)O(4) nanoparticles. The amorphicity of iron oxide nanoparticles was determined by X-ray diffraction and differential scanning calorimetry. The nanoparticles were characterized by elemental analysis, EDX, transmission electron microscopy, dynamic light scattering, Raman spectroscopy, XPS, and spot test.     

Magnetic Polymer Composite Particles Via In situ Inverse Miniemulsion Polymerization Process

We aimed at preparing magnetic iron oxide particles by the oxidation-precipitation method in order to encapsulate these particles in polymer matrices composed of poly(acrylamide-styrene sulfonic acid sodium salt). Nanocomposites were synthesized by the incorporation of surface treated magnetic nanoparticles in the synthesized polymers via in situ inverse mini-emulsion polymerization process. The study parameter was the ionic monomer content in the synthesized polymers. The structure and the morphology of the magnetic nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR and XRD showed that pure magnetite was formed and successfully encapsulated in the composite nanoparticles. The polymer encapsulation could reduce the susceptibility to leaching and could protect the magnetite particle surfaces from oxidation. The ionic monomer content had a great effect on the magnetization behavior. Magnetite prepared by the oxidation precipitation method, of 50 nm mean particle size, was embedded successfully into the polymer nanogels with a reasonable magnetic response, as proved by vibrating sample magnetometer measurement. Magnetic nanocomposites were proven to be super-ferromagnetic materials.     

Effect of the swelling degree on the formation of magnetite nanoparticles in hydrogels

Composites containing magnetite nanoparticles in poly(acrylamide-co-hydroxyethylacrylate) cross-linked using poly-ethylene-glycol-diacrylate were prepared and characterized. The magnetite was synthesized in situ in the polymer network by treatment with a water solution of Fe (II) and Fe (III). The salts were then coprecipitated by exposing the swollen gels to ammonia vapors and the obtained magnetic gels dried. The ratio acrylamide (AM)/hydroxyethylacrylate (HEA) was varied to compare matrices with different hydrophilicity. Moreover solutions with different concentration of iron salts were used to swell the gels. The effect of both the network composition and the concentration of iron salts in the swollen polymers on the final structure and properties of the dried magnetic polymers were studied. The investigation was carried out by means of electron diffraction, X-ray diffraction, vibrating sample magnetometry, small angle X-ray scattering and transmission electron microscopy. The coercivity of the magnetic composites prepared was close to zero and they provided super-paramagnetic properties. The decrease of the acrylamide content in the polymer gel and of the iron salts concentration in the swelling aqueous solution leads to the formation of amorphous particles of iron oxide. The average sizes of the magnetite nanoparticles obtained are compared.     

Iron Oxide Nanoparticles: Biosynthesis,Magnetic Behavior,Cytotoxic Effect

Iron oxide nanoparticles have attracted much attention because of their superparamagnetic properties and their potential applications in many fields such as magnetic storage devices, catalysis, sensors, superparamagnetic relaxometry (SPMR), and high-sensitivity biomolecule magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. In this study, iron oxide nanoparticles (Fe₂O₃ NPs) have been synthesized using a taranjabin (camelthorn or persian manna) aqueous solution. The synthesized Fe₂O₃ NPs were identified through powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field energy scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), vibrating-sample magnetometer (VSM) and Raman technics. The results show that the nanoparticles have a hexagonal structure with 20 to 60 nm in size. The cytotoxic effect of the synthesized nanoparticles has been tested upon application against lung cancer cell (A549) lines. It was found that there is no cytotoxic activity at lower concentrations of 200 μg/mL. The ability of the synthesized nanoparticles for lead removal in wastewaters was tested. Results show that highest concentration of adsorbent (50 mg/L) has maximum removal efficiency (96.73 %). So, synthesized Fe₂O₃ NPs can be a good candidate to use as heavy metals cleaner from contaminated waters.     

Magnetic iron oxide nanoparticles grafted N‐isopropylacrylamide/chitosan copolymer for the extraction and determination of letrozole in human biological samples

Magnetic iron oxide nanoparticles are used for the extraction of a drug from an aqueous solution. In the current study, the magnetic iron oxide nanoparticles were synthesized via a facile coprecipitation approach, and then modified by (3‐mercaptopropyl)trimethoxysilane followed by grafting thermosensitive polymer N‐isopropylacrylamide and biopolymer chitosan. Structure, morphology, size, thermal resistance, specific surface area, and magnetic properties of the grafted nanosorbent were characterized by using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, elemental analysis, thermogravimetric analysis, specific surface area analysis and vibrating sample magnetometry. The effective parameters on sorption/desorption of letrozole on grafted magnetic nanosorbent were evaluated. The best sorption of letrozole via the grafted nanosorbent occurred at 20°C at an optimum pH of 7. The extraction of trace letrozole in human biological fluids is investigated and revealed 89.1 and 97.8% recovery in plasma and urine, respectively.     

Biocompatible Magnetic Hydrogel Nanocomposite Based on Carboxymethylcellulose: Synthesis,Cell Culture Property and Drug Delivery

In this report, the synthesis of a novel biocompatible magnetic hydrogel nanocomposite based on carboxymethyl cellulose (CMC), as an eco-friend, biocompatible and green polysaccharide, is described via a facile one pot approach using magnetic iron oxide nanoparticles (MIONs) as a crosslinker. The structure of the prepared MION–CMC hydrogel nanocomposite was examined by various analytical techniques such as FTIR spectroscopy, TGA thermal analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The MIONs were generated in situ during the hydrogel formation with an average diameter size of 10 nm and a narrow size distribution. The sample was superparamagnetic with large saturation magnetization at room temperature. MION–CMC hydrogel nanocomposite showed a good ability for releasing of doxorubicin as an anticancer drug at pH 7 with case II (relaxational) transport mechanism. This outcome demonstrated that MION–CMC hydrogel nanocompositeis an attractive biocompatible candidate for widespread biomedical applications, particularly in controlled drug-targeting delivery.     

Investigation of tannery liming waste water using green synthesised iron oxide nano particles

ABSTRACT

The present study aimed that non-toxic, less expensive, easily available, safer to environment and previously unreported Eclipta prostrata leaf extract is used for the green synthesis of iron oxide nano particles. The iron oxide nanoparticles (NPs) were characterised by UV–visible, Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tannery effluents treated by photodegradation process and the removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD) and sulphide were analysed. The maximum removal efficiency correlated with operating parameters was explained using response surface methodology with Boxmen Beckmen design.     

Synthesis of star-shaped CuO nanoparticles supported on magnetic functionalized graphene: Catalytic and antibacterial activity

In this study, graphene oxide was modified during consecutive functionalization steps with 1,4-diphenylamine, cyanuric chloride, and ethylenediamine. Then, star-shaped CuO nanoparticles were synthesized on modified graphene oxide using the seed-mediated growth method in which nucleation, growth stages, and reduction of graphene oxide to graphene occurred simultaneously. After ensuring successful synthesis of CuO nanoparticles and to facilitate recycling, a magnetization process was utilized by adding iron oxide nanoparticles. This nanocomposite was characterized by transmission electron microscopy, X-ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The prepared heterogeneous catalyst was investigated for the reduction of organic dyes in the presence of NaBH₄ as a reducing reagent. The kinetic data obtained for the reduction of methyl orange (MO), methylene blue (MB), 4-nitrophenol (4-NP), and rhodamine 6G (Rh6G) were fitted to first-order rate equations, and the calculated rate constants for the reduction of MO, MB, 4-NP and Rh6G were as follows: −0.091, −0.071, −0.045, and 0.040, respectively. As star-shaped CuO nanoparticles showed a higher antibacterial effect compared to spherical-shaped CuO nanoparticles, the antibacterial activity of star-shaped CuO nanoparticles immobilized on magnetic functionalized graphene was evaluated against Gram-positive and Gram-negative bacteria through an agar well diffusion assay and demonstrated more antibacterial activity against gram-positive bacteria.     

Microwave and UV Assisted Methods for Obtaining Novel Composites Based on Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> with Embedded Gold Nanoparticles

Metallic nanoparticles embedded into the structure of metal oxides may play a role of catalytic substances. Such composites are mostly applied in oxidation reactions. The paper presents two one-step-methods for obtaining nanocomposites of gold embedded in the structure of iron oxide matrices (nanoAu/Fe₂O₃). Gold nanoparticles were formed in situ in the process of iron hydroxide dehydration. Thanks to the use of tannic acid it was possible to effectively reduce gold ions and stabilize the forming metal nanoparticles. The composites were prepared in the fields of microwave, ultraviolet radiation. The physicochemical properties of products were determined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray analysis and high-resolution transmission electron microscopy technique with EDS and elemental mapping mode. Also, the catalytic activity of the nanocomposites obtained was evaluated based on the process of methyl orange degradation. It was observed that products obtained according to the microwave radiation method are characterized by improved applying properties.     

Preparation and in vitro cytotoxicity study of poly (aspartic acid) stabilized magnetic nanoparticles

Biocompatible magnetic nanoparticles were prepared by co-precipitation method in the presence of poly (aspartic acid) (PAsp) as stabilizer, which was one of the most extensively studied and used poly(amino acids). As a biocompatible dispersant, PAsp was successfully attached to the Fe₃O₄ nanoparticles, which was approved by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). From X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) measurement results, it was found that PAsp stabilized iron oxide nanoparticles possess excellent Fe₃O₄ crystal structure and superparamagnetic property. Compared with trisodium citrate stabilized magnetic nanoparticles, PAsp stabilized magnetic nanoparticles were biocompatible and with lower cytotoxicity, which makes it more applicable in medicine, biology and biomaterial science.     

Embedding magnetic nanoparticles into polysaccharide-based hydrogels for magnetically assisted bioseparation.

Based on the preparation of biocompatible polysaccharide-based hydrogels with stimuli-responsive properties by the copolymerization of maleilated carboxymethyl chitosan with N-isopropylacrylamide, novel magnetic hybrid hydrogels were fabricated by the in situ embedding of magnetic iron oxide nanoparticles into the porous hydrogel networks. Scanning electron microscopy (SEM) and thermogravimetric (TG) analyses showed that the size, morphology, and content of the iron oxide nanoparticles formed could be modulated by controlling the amount of maleilated carboxymethyl chitosan. As confirmed by X-ray diffractometry (XRD), equilibrium swelling ratio, and differential scanning calorimetry (DSC) measurements, the embedding process did not induce a phase change of the magnetic iron oxide nanoparticles, and the resultant hybrid hydrogels could retain the pH- and temperature-responsive characteristics of their hydrogel precursors. By investigating the partition coefficients of bovine serum albumin as a model protein, this magnetic hydrogel material was found to hold a potential application in magnetically assisted bioseparation.     

Synthesis and characterizations of amorphous carbon nanotubes by pyrolysis of ferrocene confined within AAM templates

Amorphous carbon nanotubes (a-CNTs) are synthesized by pyrolysis of ferrocene confined in the nanopores of the anodic alumina membrane (AAM) and characterized by field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), and Raman spectroscopy. It is shown that the a-CNT has an ultrathin amorphous wall (approximately 3 nm) and a relatively large diameter (approximately 50 nm), and is capsulated with iron oxide nanoparticles. It is found that the growth of the a-CNTs is governed mainly by the template limitation effect. Electrical transport measurements on individual a-CNTs demonstrate that the a-CNT may be connected with electrodes via either ohmic or Schottky contacts, and the resisitivity of the a-CNTs was measured to be 4.5 x 10(-3) Omega cm.     

pH-dependent magnetic phase transition of iron oxide nanoparticles synthesized by gamma-radiation reduction method

In this study, the influence of pH variation on structural and magnetic phase transition of gamma radiolytic synthesized iron oxide nanoparticles is investigated. The structure and magnetic properties of irradiated samples are characterized using X-ray diffraction, Fourier transfer infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometer. It was found that, in acidic irradiated solution, Fe³⁺ ions make various complexes with polyvinyl alcohol and water molecules which exhibit a multiphase magnetic property as a mixture of dia and paramagnetic materials. On the other hand, in basic condition, rate of radiation induced reduction of Fe³⁺ ions increased which leads to the formation of superparamagnetic Fe₃O₄ nanoparticles. By increasing pH value, in strong basic condition, the tendency of paramagnetic iron (III) oxy-hydroxide formation was high compared to other phases. This variation in the magnetic properties was explained based on iron ions reduction mechanism and the variation of the ligands’ properties during formation of nanoparticles under irradiation.     

Highly efficient removal of Cr(VI) from wastewater via adsorption with novel magnetic Fe3O4@C@MgAl-layered double-hydroxide

Novel magnetic Fe₃O₄@C@MgAl-layered double-hydroxide (LDH) nanoparticles have been successfully prepared by the chemical self-assembly methods. The properties of surface functional groups, crystal structure, magnetism and surface morphology of magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravity-differential thermal gravity (TG-DTG), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The adsorption studies of the novel adsorbent in removing heavy metals Cr (VI) from waste water showed that the maximum absorption amount of Cr(VI) was 152.0 mg/g at 40℃ and pH 6.0. The excellent adsorption capacity of the Fe₃O₄@C@MgAl-LDH nano-absorbents plus their easy separation, environmentally friendly composition and reusability makes them more suitable adsorbents for the removal of metal ions from waste water.     

Ultrafine agarose-coated superparamagnetic iron oxide nanoparticles (AC-SPIONs): a promising sorbent for drug delivery applications

A method for one-step synthesis of ultrafine agarose-coated superparamagnetic iron oxide nanoparticles (AC-SPIONs) was developed. The method is facile and fast and requires no organic solvent or surfactant. The average particle size of the prepared AC-SPIONs was only 20–40 nm with a narrow size distribution and with large saturation magnetization at room temperature. The obtained ultrafine nanogel particles were characterized by scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, transmission electron microscopy and vibrating sample magnetometer techniques. The AC-SPIONs were epoxy-activated by epichlorohydrin and aminated by ammonium hydroxide. The amination of the particles was investigated by the Kaiser test. The adsorption of two model compounds (gallic acid and ellagic acid) on the functionalized nanoparticles and their releases from them were investigated spectrophotometrically in three different pH values under biological conditions. The functionalized AC-SPIONs displayed good adsorption and in vitro drug release in a phosphate-buffered saline (pH 7.4). The ultrafine AC-SPIONs can be potentially used in magnetic solid-phase extraction, drug delivery, protein purification and enzyme immobilization methods.