共查询到20条相似文献,搜索用时 11 毫秒
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Liu HM Wu SH Lu CW Yao M Hsiao JK Hung Y Lin YS Mou CY Yang CS Huang DM Chen YC 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(5):619-626
Tumblerlike magnetic/fluorescein isothiocyanate (FITC)-labeled mesoporous silica nanoparticles, Mag-Dye@MSNs, have been developed, which are composed of silica-coated core-shell superparamagnetic iron oxide (SPIO@SiO(2)) nanoparticles co-condensed with FITC-incorporated mesoporous silica. Mag-Dye@MSNs can label human mesenchymal stem cells (hMSCs) through endocytosis efficiently for magnetic resonance imaging (MRI) in vitro and in vivo, as manifested by using a clinical 1.5-T MRI system with requirements of simultaneous low incubation dosage of iron, low detection cell numbers, and short incubation time. Labeled hMSCs are unaffected in their viability, proliferation, and differentiation capacities into adipocytes and osteocytes, which can still be readily detected by MRI. Moreover, a higher MRI signal intensity decrease is observed in Mag-Dye@MSN-treated cells than in SPIO@SiO(2)-treated cells. This is the first report that MCM-41-type MSNs are advantageous to cellular uptake, as manifested by a higher labeling efficiency of Mag-Dye@MSNs than SPIO@SiO(2). 相似文献
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We present a new approach for the fabrication of thermoresponsive polymer microcapsules with mobile magnetic cores that undergo a volume phase-transition upon changing the temperature and are collected under an external magnetic field. We have prepared organic/inorganic composite microspheres with a well-defined core-shell structure that are composed of a crosslinked poly(N-isopropylacrylamide) (PNIPAM) shell and silica cores dotted centrally by magnetite nanoparticles. Since the infiltration of template-decomposed products is dependent on the permeability of PNIPAM shells triggered by changes of exterior temperature, the silica layer sandwiched between the magnetic core and the PNIPAM shell was quantitatively removed to generate PNIPAM microcapsules with mobile magnetic cores by treatment with aqueous NaOH solution. For development of the desired multifunctional microcapsules, modification of the unetched silica surface interiors can be realized by treatment with a silane coupling agent containing functional groups that can easily bind to catalysts, enzymes, or labeling molecules. Herein, fluorescein isothiocyanate (FITC), which is a common organic dye, is attached to the insides of the mobile magnetic cores to give PNIPAM microcapsules with FITC-labeled magnetic cores. In this system, it can be expected that an extension of the functionalization of the cavity properties of smart polymer microcapsules is to immobilize other target molecules onto the mobile cores in order to introduce other desired functions in the hollow cage. 相似文献
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具有核-壳结构的金纳米包覆的磁性纳米粒子,既具有磁性纳米粒子的特点又增加了金纳米的表面化学性质,近年来受到研究人员的广泛关注。简要综述了近年来国内外制备2类核-壳结构的金包铁磁性纳米复合材料的研究进展及相关应用,并对其应用前景进行了展望。 相似文献
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Sievers S Braun KF Eberbeck D Gustafsson S Olsson E Schumacher HW Siegner U 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(17):2675-2679
The quantitative measurement of the magnetization of individual magnetic nanoparticles (MNPs) using magnetic force microscopy (MFM) is described. Quantitative measurement is realized by calibration of the MFM signal using an MNP reference sample with traceably determined magnetization. A resolution of the magnetic moment of the order of 10(-18) A m(2) under ambient conditions is demonstrated, which is presently limited by the tip's magnetic moment and the noise level of the instrument. The calibration scheme can be applied to practically any magnetic force microscope and tip, thus allowing a wide range of future applications, for example in nanomagnetism and biotechnology. 相似文献
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Highly Fluorescent Magnetic Nanobeads with a Remarkable Stokes Shift as Labels for Enhanced Detection in Immunoassays 下载免费PDF全文
Francesca Salis Ana B. Descalzo Elena Benito‐Peña María C. Moreno‐Bondi Guillermo Orellana 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
Fluorescence immunoassays are popular for achieving high sensitivity, but they display limitations in biological samples due to strong absorption of light, background fluorescence from matrix components, or light scattering by the biomacromolecules. A powerful strategy to overcome these problems is introduced here by using fluorescent magnetic nanobeads doped with two boron‐dipyrromethane dyes displaying intense emission in the visible and near‐infrared regions, respectively. Careful matching of the emission and absorption features of the dopants leads to a virtual Stokes shift larger than 150 nm achieved by an intraparticle Förster resonance energy transfer (FRET) process between the donor and the acceptor dyes. Additionally, the magnetic properties of the fluorescent beads allow preconcentration of the sample. To illustrate the usefulness of this approach to increase the sensitivity of fluorescence immunoassays, the novel nanoparticles are employed as labels for quantification of the widely used Tacrolimus (FK506) immunosuppressive drug. The FRET‐based competitive inhibition immunoassay yields a limit of detection (LOD) of 0.08 ng mL?1, with a dynamic range (DR) of 0.15–2.0 ng mL?1, compared to a LOD of 2.7 ng mL?1 and a DR between 4.1 and 130 ng mL?1 for the immunoassay carried out with direct excitation of the acceptor dye. 相似文献
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利用浸渍法合成了Co3O4/SBA-15和CoFe2O4/SBA-15介孔纳米磁性材料, 并利用X射线粉末衍射(XRD)、 透射电子显微镜(TEM)、 场发射扫描电子显微镜(FESEM)及振动样品磁强计(VSM)对样品的微观结构和磁性能进行了分析。结果显示, Co3O4及CoFe2O4纳米颗粒分布在SBA-15介孔材料的孔道中, 可有效提高SBA-15介孔材料的磁性能。研究发现, SBA-15介孔纳米磁性材料的磁特性由掺杂的纳米磁性颗粒的性质决定, 其磁性能随Co3O4及CoFe2O4含量的增加而升高, 矫顽力可达400Oe, 饱和磁化强度达9emu/g。 相似文献
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Synthesis of high magnetic moment CoFe nanoparticles via interfacial diffusion in core/shell structured Co/Fe nanoparticles 总被引:1,自引:0,他引:1
We report the synthesis of high magnetic moment CoFe nanoparticles via the diffusion of Co and Fe in core/shell structured
Co/Fe nanoparticles. In an organic solution, Co nanoparticles were coated with a layer of Fe to form a Co/Fe core/shell structure.
Further raising the solution temperature led to inter-diffusion of Co and Fe and formation of CoFe alloy nanoparticles. These
nanoparticles have high saturation magnetization of up to 192 emu/g CoFe and can be further stabilized by thermal annealing
at 600 °C.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
These two authors made an equal contribution to the work. 相似文献
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A photokilling approach for pathogenic bacteria is demonstrated using a new type of magnetic nanoprobe as the photokilling agent. In addition to their magnetic property, the nanoprobes have other features including a photocatalytic property and the capacity to target bacteria. The nanoprobes comprise iron oxide/titania (Fe(3)O(4)@TiO(2)) core/shell magnetic nanoparticles. As dopamine molecules can self-assemble onto the surface of the titania substrate, dopamine is used as the linker to immobilize succinic anhydride onto the surfaces of the Fe(3)O(4)@TiO(2) nanoparticles. This is followed by the immobilization of IgG via amide bonding. We demonstrate that the IgG-Fe(3)O(4)@TiO(2) magnetic nanoparticles not only have the capacity to target several pathogenic bacteria, but they also can effectively inhibit the cell growth of the bacteria targeted by the nanoparticles under irradiation of a low-power UV lamp within a short period. Staphylococcus saprophyticus, Streptococcus pyogenes, and antibiotic-resistant bacterial strains, such as multiantibiotic-resistant S. pyogenes and methicillin-resistant Staphylococcus aureus (MRSA), are used to demonstrate the feasibility of this approach. 相似文献
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Sumit Pokhriyal 《Materials Science & Technology》2020,36(13):1503-1506
In this letter, we report a simple process to derive in situ surface stabilised intrinsic CdSe nanoparticles (NPs) showing room temperature ferromagnetism (RTFM). The observed RTFM is primarily attributed to the lattice strain (ε) in the NPs supported by an effective core (CdSe)-shell (surface layer) charge transfer mechanism. The synthesis method allows precise control over particle morphology and dispersity, and is highly convenient in tuning the magnetic properties for pertinent applications. Highlights
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Magnetic CdSe nanoparticles were synthesized by a facile process.
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In situ formed graphitic-carbon layer on the surface stabilises the nanoparticles.
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The process permits precise control over particle morphology and dispersity.
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The technique is also convenient in tuning the magnetic properties.
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Monodispersed magnetic CdSe nanoparticles have potential applications in modern optoelectronics.
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Cui Sheng Shen Xiaodong Shi Ruihua Lin Benlan Chen Ping 《Frontiers of Materials Science in China》2007,1(4):383-387
The objective of this paper was to prepare paclitaxel-loaded microspheres, a kind of target-orientation anticancer drug. The
paclitaxel-loaded microspheres were prepared with magnetic Fe3O4 nanoparticles and taxol. The morphology was characterized by scanning electron microscopy (SEM), and the average size and
the size distribution were determined by a laser-size distributing instrument. High performance liquid chromatography (HPLC)
was used to measure the paxlitaxel content. Experimental results indicated that the effective drug loading and the entrapment
ratio of paclitaxel-loaded microspheres were 1.83% and 92.62%, respectively. 相似文献
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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。 相似文献
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Ehresmann A Lengemann D Weis T Albrecht A Langfahl-Klabes J Göllner F Engel D 《Advanced materials (Deerfield Beach, Fla.)》2011,23(46):5568-5573
Domain wall movement assisted transport of particles: exchange-biased samples with designed stripe-domains show strong stray fields and an asymmetric magnetization reversal. Using these characteristics superparamagnetic particles can be trapped and transported directly on the sample over large-scale areas. High particle velocities, small external fields, and automatically reduced particle clustering allow broad applicability of this transport method. 相似文献
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Using magnetic nanoparticles to enhance gene transfection, a recently developed technique termed magnetofection, has been
shown to be a powerful technology in gene delivery. The most widely used magnetic nanoparticles in this area are those coated
with polyethyleneimine, which is a well known nonviral transfection agent. In this article, we report methods to control the
aggregate size of polyethyleneimine-coated magnetite particles. These particles were then used to enhance transfection of
green fluorescent protein (GFP) into NIH 3T3 cells in vitro. We find that the aggregate size of the particles has a great effect on their performance in magnetofection, with less aggregated
magnetic particles being more effective in enhancing the gene transfection.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
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通过机械化学合成方法制备了矫顽力分别为2.95×106、2.83×106和8.60×105 A/m的分散的单晶纳米Sm2Co7、SmCo5和Sm2Co17硬磁颗粒。研究了球磨时间、原料配比和退火工艺等对所制备的纳米永磁颗粒的微观组织、结构和磁性能的影响。结果表明,机械化学球磨时间至少是4h或更长时间才能获得Sm-Co硬磁合金粉末。原料经过高能球磨后、未退火时,由于大部分颗粒为非晶结构,矫顽力较低,随着退火温度的上升,矫顽力增大,当退火温度为600℃时,达到最大值为2.83×106 A/m,然后,随着退火温度的进一步升高,矫顽力减小。Sm-Co纳米颗粒的粒径随着退火温度的降低而明显减小。 相似文献