Gold-coated iron oxide nanoparticles as a T2 contrast agent in magnetic resonance imaging

Gold-coated iron oxide (Fe3O4) nanoparticles were synthesized for use as a T2 contrast agent in magnetic resonance imaging (MRI). The coated nanoparticles were spherical in shape with an average diameter of 20 nm. The gold shell was about 2 nm thick. The bonding status of the gold on the nanoparticle surfaces was checked using a Fourier transform infrared spectrometer (FTIR). The FTIR spectra confirmed the attachment of homocysteine, in the form of thiolates, to the Au shell of the Au-Fe3O4 nanoparticles. The relaxivity ratio, R2/R1, for the coated nanoparticles was 3-fold higher than that of a commercial contrast agent, Resovist, which showed the potential for their use as a T2 contrast agent with high efficacy. In animal experiments, the presence of the nanoparticles in rat liver resulted in a 71% decrease in signal intensity in T2-weighted MR images, indicating that our gold-coated iron oxide nanoparticles are suitable for use as a T2 contrast agent in MRI.     

纳米金磁颗粒的组装法制备及其核酸分离性能

以丙烯酰胺为单体,采用原位聚合法制备了Fe3O4/聚丙烯酰胺纳米磁粒(Fe3O4/PAM);利用胺基与金的相互作用,借助自组装法在Fe3O4/PAM表面组装金胶体制备了草莓型纳米金磁颗粒(Fe3O4/PAM/Au);用TEM、VSM、UV-vis对其进行了表征,并考察了表面修饰核酸探针的金磁颗粒对核酸靶分子的分离能力。结果表明,Fe3O4/PAM/Au粒子的粒径为36～56nm,具有超顺磁性,饱和磁化强度为31.2emu/g,分散在磷酸盐缓冲液中的Fe3O4/PAM/Au完全磁分离的时间为6min。修饰核酸探针的Fe3O4/PAM/Au粒子可以借助核酸杂交作用分离核酸靶分子,分离能力为118pmol/mg。     

Nano-scale Au supported on Fe3O4: characterization and application in the catalytic treatment of 2,4-dichlorophenol

Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Gold nanoparticles supported on Fe(3)O(4) have been tested in the gas phase (1 atm, 423 K) HDC of 2,4-dichlorophenol. Two 1% w/w supported gold catalysts have been prepared by: (i) stepwise deposition of Au on α-Fe(2)O(3) with subsequent temperature-programmed reduction at 673 K (Au/Fe(3)O(4)-step); (ii) direct deposition of Au on Fe(3)O(4) (Au/Fe(3)O(4)-dir). TEM analysis has established the presence of Au at the nano-scale with a greater mean diameter (7.6 nm) on Au/Fe(3)O(4)-dir relative to Au/Fe(3)O(4)-step (4.5 nm). We account for this difference in terms of stronger (electrostatic) precursor/support interactions in the latter that can be associated with the lower pH point of zero charge (with respect to the final deposition pH) for Fe(2)O(3). Both catalysts promoted the preferential removal of the ortho-Cl substituent in 2,4-dichlorophenol, generating 4-chlorophenol and phenol as products of partial and total HDC, respectively, where Au/Fe(3)O(4)-step delivered a two-fold higher rate (2 × 10(-4) mol(Cl) h(-1) m(Au)(-2)) when compared with Au/Fe(3)O(4)-dir. This unprecedented selectivity response is attributed to activation of the ortho-C-Cl bond via interaction with electron-deficient Au nanoparticles. The results demonstrate the feasibility of a controlled recovery/recycling of chlorophenol waste using nano-structured Au catalysts.     

One-step solvothermal synthesis of Fe3O4@C core-shell nanoparticles with tunable sizes

We report the synthesis of Fe3O4@C core-shell nanoparticles (FCNPs) by using a facile one-step solvothermal method. The FCNPs consisted of Fe3O4 particles as the cores and amorphous uniform carbon shells. The content of Fe3O4 is up to 81.6 wt%. These core-shell nanoparticles are aggregated by primary nanocrystals with a size of 10-12 nm. The FCNPs possess a hollow interior, high magnetization, excellent absorption properties and abundant surface hydroxyl groups. A possible growth mechanism of the FCNPs is proposed. The role of glucose in regulating the grain size and morphology of the particles is discussed. The absorption properties of the FCNPs towards Cr(VI) in aqueous solution is investigated. We demonstrate that the FCNPs can effectively remove more than 90 wt% of Cr(VI) from aqueous solution.     

Evaluation of Iron and Au-Fe3O4 Ferrite Nanoparticles for Biomedical Application

Journal of Superconductivity and Novel Magnetism - In the present study, Fe3O4 (FO) nanoparticles and Au-Fe3O4 (AFO) nanocomposite have been synthesised by using sedimentary method. The samples...     

Fe3O4磁性纳米颗粒的合成与接枝聚合修饰（英文）

以氨水作为沉淀剂并控制溶液的pH值,采用Fe3+和Fe2+共沉淀法制得了磁性四氧化三铁纳米颗粒。合成的磁性纳米颗粒通过高分辨透射电镜、X射线衍射仪、傅里叶变换红外光谱仪进行了表征。四氧化三铁纳米颗粒的粒径约为10nm,其表面含有丰富的羟基。为了增强磁性四氧化三铁纳米颗粒和聚合物基质之间的相互作用,在纳米颗粒的表面接枝上乙烯基单体。傅里叶变换红外光谱仪和热重分析仪的测试结果显示,聚合物链共价结合在纳米颗粒表面。表面接枝聚合后,四氧化三铁纳米颗粒由极性转变为非极性。     

Structural verification and optical characterization of SiO2–Au–Cu2O nanoparticles

In this paper, SiO₂–Au–Cu₂O core/shell/shell nanoparticles were synthesized by reducing gold chloride on 3-amino-propyl-triethoxysilane molecules attached silica nanoparticle cores for several stages. Cu₂O nanoparticles were synthesized readily with the size of 4–5 nm using a simple route of sol–gel method Then, they were clung to the surface of Au seeds. The morphology of the resultant particles was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Transmission electron microscopy images demonstrate growth of monodispersed gold seeds and Cu₂O nanoparticles in narrow size up to 10 nm and 5 nm, respectively. The presence of gold and Cu₂O coating was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. Absorption spectroscopy shows considerably 40 nm blue shift in absorption edge for SiO₂–Au–Cu₂O nanostructure rather than SiO₂–Au core/shell nanoparticles.     

Possible weak ferromagnetism in pure and M (Mn, Cu, Co, Fe and Tb) doped NiGa2O4 nanoparticles

We report on the structural and magnetic properties of nanoparticles of NiGa2O4 and 5 at.% M doped (M = Mn2+, Cu2+, Co2+, Fe3+ and Tb3+) at Ga site of NiGa2O4, synthesized by gel-combustion method. The particle size, as investigated by X-ray diffraction and transmission electron microscopy, could be fine tuned by a controlled annealing process. Weak ferromagnetism becomes significant, when the particles are in the nano regime (5-7 nm). The magnetization becomes insignificant at larger particle size ( 150 nm). Cu2+ and Tb3+ doped NiGa2O4 nanoparticles showed relatively large room temperature ferromagnetism compared to other doped (Fe, Mn and Co) and undoped NiGa2O4 samples. The weak ferromagnetism observed in the nanoparticles of NiGa2O4, which is antiferromagnetic in the bulk, is due to the surface disordered states with uncompensated spins.     

Magnetic field switching of nanoparticles between orthogonal microfluidic channels

This paper reports on the manipulation of magnetic nanoparticles between microfluidic channels by the application of an external magnet. Two orthogonal channels were prepared using standard PDMS techniques with pressure-driven flow used to deliver the mobile phase. To study the ability to control magnetic nanoparticles within micrometer-sized channels, Fe2O3, MnFe2O4, and Au nanoparticle samples were compared. For the magnetic particles, transfer between flow streams is greatly increased by placing a permanent magnet beneath the intersection of the channels, but no change is observed for the nonmagnetic Au particles. More nanoparticles are magnetically transferred into the orthogonal channel as the solvent flow rate decreases. We demonstrate the ability to use this technique to perform multiple injections of plugs of magnetic particles by periodic application of a magnetic field.     

磁性羧甲基化壳聚糖纳米粒子的制备与表征

以化学共沉淀法制备了Fe3O4纳米粒子,壳聚糖经羧甲基化改性后接枝在Fe3O4颗粒表面,得到了磁性羧甲基化壳聚糖(Fe3O4/CMC)纳米粒子.利用透射电镜(TEM)、X射线衍射(XRD)、傅立叶红外光谱(FT-IR)及磁性测试对产物进行了表征.TEM表明Fe3O4纳米粒子被CMC包覆,粒径约10 nm;XRD分析表明复合纳米粒子中磁性物质为Fe3O4;FT-IR表明壳聚糖发生羧甲基反应以及在Fe3O4表面的接枝反应.Fe3O4/CMC纳米粒子具有超顺磁性,比饱和磁化强度25.73 emu/g,有良好的磁稳定性.     

A novel nanostructured iron oxide-gold bioelectrode for hydrogen peroxide sensing

Fe(3)O(4) nanoparticles covalently linked to a gold electrode have been used for immobilizing catalase (CAT) enzyme to sense the presence of various concentrations of H(2)O(2). These nanoparticles ranging from 20 to 30 nm were synthesized by thermal co-precipitation of ferric and ferrous chlorides. SEM and XRD have been used for morphological and structural characterization of Fe(3)O(4) nanoparticles. CAT enzyme was linked covalently to the surface of iron oxide using carbodiimide in phosphate buffer (pH 7.4) at 4?°C. The enzyme-iron oxide link was confirmed by FT-IR spectroscopy. Sensing studies carried out using cyclic voltammetry showed a linear response of the CAT/nano Fe(3)O(4)/Au bioelectrode towards H(2)O(2) between 1.5 and 13.5 μM with a very sharp response time of 2 s.     

Fe3O4纳米粒子的制备与超顺磁性

采用红外光谱、X射线衍射、透射电子显微镜和振动样品磁强计对用化学共沉淀法制备出的纳米Fe3O4粒子进行了形貌、结构及磁性能表征.其中,红外和XRD测试结果表明制备出的Fe3O4粒子的物态和晶相结构;透射电子显微镜照片表明制备出的纳米四氧化三铁成球性好,且大部分四氧化三铁粒子的粒径在10nm左右;磁化曲线表明制备出的Fe3O4粒子无剩磁和矫顽力,具有超顺磁性.并且,将制备出的纳米Fe3O4粒子和块状Fe3O4的磁性能进行对比,探讨了Fe3O4由块状的亚铁磁性向纳米级的超顺磁性转变的原因.     

Fe3O4/Ni复合纳米颗粒的制备及其微波吸收特性

采用电爆炸技术,合成了粒径约为70nm 的Ni纳米颗粒,以3-巯基丙基三甲氧基硅烷偶联剂(MPTS)对Ni颗粒进行表面改性,利用共沉淀法对改性Ni颗粒进行包覆得到核-壳结构的复合纳米颗粒。将获得的复合纳米颗粒作为微波吸收剂, 并以不同比例分散到热固性酚醛树脂中,涂刷在200mm×200mm的金属板上,用RAM反射率远场RCS测量法研究了微波吸收特性。研究表明,核-壳结构Fe₃O₄/Ni复合颗粒作为微波吸收剂,在相同质量比条件下,其微波吸收性能明显优于纯Ni纳米颗粒或Fe₃O₄纳米颗粒的情况,并且在Fe₃O₄/Ni核-壳结构复合纳米颗粒中随着镍含量的提高,微波吸收增强,而随着Fe₃O₄含量的增加,微波吸收频段向高频段移动。     

CdTe@Fe3O4磁性复合纳米粒子的合成与表征

本文通过层层自组装技术（1ayer-by—layer,LBL）成功制备了CdTe@Fe3O4磁性荧光复合纳米粒子,并对其特性和应用进行了讨论．首先,采用化学共沉淀法,以NaOH为沉淀剂,Fe^2＋和Fe^3＋物质的量的比为1：2．在50℃水相中电磁搅拌30min,制备出具有磁性的纳米Fe3O4,然后表面修饰1,6-己二胺．通过透射电镜（transmission electron microscopy,TEM）对其进行观察,粒径在10nm左右．核壳cdTe@Fe3O4复合功能纳米粒子的合成表明：Fe3O4和cdTc物质的量的比为1：3,pH=6．0,温度30℃,反应时间30min为其最佳合成条件．通过TEM、紫外和荧光光谱对合成的纳米粒子分别进行了表征．cdTe@Fe3O4粒径在12～15nm,最大发射波长从530nm红移到570nm,而最大吸收波长则从530nm红移到535mm．结果表明,磁性Fe3O4表面成功覆盖了CdTe壳层．核壳型CdTe@Fe3O4磁性荧光复合纳米粒子的应用能够实现对DNA进行简便快捷的标记、传感和分离．     

交联P（St-r-AA）包覆Fe3O4粒子的制备及对Cu2＋的吸附

用乳液聚合的方法合成了交联P（St-r-AA）包覆的Fe3O4粒子,研究了该类粒子对Cu2＋离子的吸附性能。透射电镜（TEM）表明,交联的P（St-r-AA）包覆的Fe3O4磁性粒子粒径约100 nm;X射线衍射（XRD）分析表明,磁性粒子中磁性物质为尖晶石结构的Fe3O4;红外光谱（FT-IR）表明,Fe3O4表面的...     

Fe3O4磁性纳米颗粒的合成及其调控

利用水解共沉淀法制备了Fe3O4纳米颗粒,研究了温度和pH值对Fe3O4纳米颗粒粒径、形貌的影响关系。研究结果表明,反应温度从30℃升高到90℃,Fe3O4颗粒的粒径从6～8nm增大到10～12nm;同时,Fe3O4颗粒的饱和磁矩也随着Fe3O4颗粒粒径的增加而升高。溶液pH值会影响Fe3O4纳米颗粒的形状,高pH值易使合成的Fe3O4纳米颗粒为四方形,随着pH值的降低,Fe3O4纳米颗粒向球形转变。Fe3O4纳米颗粒的粒径和形状的可控性为进一步合成、调控Fe3O4电磁功能复合材料奠定了良好基础。     

Facile one-pot preparation, surface functionalization, and toxicity assay of APTS-coated iron oxide nanoparticles

We report a facile approach to synthesizing 3-aminopropyltrimethoxysilane (APTS)-coated magnetic iron oxide (Fe(3)O(4)@APTS) nanoparticles (NPs) with tunable surface functional groups for potential biomedical applications. The Fe(3)O(4) NPs with a mean diameter of 6.5?nm were synthesized by a hydrothermal route in the presence of APTS. The formed amine-surfaced Fe(3)O(4)@APTS NPs were further chemically modified with acetic anhydride and succinic anhydride to generate neutral (Fe(3)O(4)@APTS?Ac) and negatively charged (Fe(3)O(4)@APTS?SAH) NPs. These differently functionalized NPs were extensively characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry analysis, zeta potential measurements, and T(2) relaxometry. The cytotoxicity of the particles was evaluated by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric viability assay of cells along with microscopic observation of cell morphology. The hemocompatibility of the particles was assessed by in vitro hemolysis assay. We show that the hydrothermal approach enables an efficient modification of APTS onto the Fe(3)O(4) NP surfaces and the formed NPs with different surface charge polarities are water-dispersible and colloidally stable. The acetylated Fe(3)O(4)@APTS?Ac NPs displayed good biocompatibility and hemocompatibility in the concentration range of 0-100?μg?ml(-1), while the pristine Fe(3)O(4)@APTS and Fe(3)O(4)@APTS?SAH particles started to display slight cytotoxicity at a concentration of 10?μg?ml(-1). The findings from this study suggest that the Fe(3)O(4)@APTS NPs synthesized by the one-pot hydrothermal route can be surface modified for various potential biomedical applications.     

Aerosol-assisted synthesis of thiol-functionalized mesoporous silica spheres with Fe3O4 nanoparticles

Thiol-functionalized mesoporous silica spheres having Fe3O4 nanoparticles are fabricated in one-pot by aerosol-assisted synthesis. A TEM image shows that Fe3O4 nanoparticles are successfully embedded within the mesoporous silica spheres. SEM images and SAXS profiles reveals that the encapsulating Fe3O4 nanoparticles do not affect the ordering of a mesoporous structure. The spherical morphologies are also well retained. The presence of cage-type mesopores with uniform size is confirmed by N2 adsorption-desorption isotherms and TEM observations. The spray-dried thiol-functionalized particles with Fe3O4 nanoparticles effectively adsorb mercury (II) ions due to their strong interaction to thiol groups embedded in the framework. The particles with the amount of Fe3O4 nanoparticles (3.5 wt%) show a saturated magnetization (over 1.0 emu/g). This magnetic property is useful for practical collection with magnet.     

乙酰丙酮铁为催化剂源在碳纤维表面生长碳纳米管的工艺研究

以乙酰丙酮铁为催化剂源,三甘醇为溶剂,通过溶剂热法在碳纤维表面负载催化剂前驱体,在H2与N2中一定温度下进行还原,采用化学气相沉积法在碳纤维表面生长碳纳米管。研究了催化剂的负载条件和碳纳米管的生长条件,采用XRD、FTIR、RAMAN对乙酰丙酮铁在三甘醇中反应在碳纤维表面负载催化剂前驱体产物进行分析,用SEM、TEM对催化剂前驱体粒子及碳纳米管的形貌进行表征。结果表明:催化剂前驱体为粒径30nm左右的Fe3O4颗粒,当催化剂的还原温度为415℃、还原时间为60min时,Fe3O4颗粒还原成纳米Fe颗粒;当碳纳米管的生长温度为750℃、生长时间为30min、气流体积比为V(N2)∶V(H2)∶V(C2H2)=50∶10∶10时能在碳纤维表面生长出形貌均一、管径为30~60nm的碳纳米管。     

Low-temperature phase and morphology transformations in noble metal nanocatalysts

In situ real-time x-ray diffraction was used to study temperature-induced structural changes of 1-5 nm Au, Pt, and AuPt nanocatalysts supported on silicon substrates. Synchrotron-based x-ray diffraction indicates that the as-synthesized Au and Au(64)Pt(36) nanoparticles have a non-crystalline structure, while the Pt nanoparticles have the expected cubic structure. The nanoparticles undergo dramatic structural changes at temperatures as low as 120?°C. During low-temperature annealing, the Au and AuPt nanoparticles first melt and then immediately coalesce to form 4-5 nm crystalline structures. The Pt nanoparticles also aggregate but with limited intermediate melting. The detailed mechanisms of nucleation and growth, though, are quite different for the three types of nanoparticles. Most interestingly, solidification of high-density AuPt nanoparticles involves an unusual transient morphological transformation that affects only the surface of the particles. AuPt nanoparticles on silicon undergo partial phase segregation only upon annealing at extremely high temperatures (800?°C).