首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
李凤  康经武 《色谱》2014,32(4):369-375
发展了一种新型的磁性纳米粒子应用于人血清中特异性糖蛋白的亲和富集。制备的磁性纳米粒子具有核/壳/壳结构,即由Fe3O4磁性粒子/硅胶层/有机聚合物外层构成。伴刀豆凝集素A(Con A)以共价键合的形式通过短链聚乙二醇固定在粒子表面,实现了人血清中特异性糖蛋白的高效富集。富集的蛋白经过胰蛋白酶酶解后,所得的肽段经离线的二维色谱分离,用高分辨质谱共鉴定出80种蛋白。通过NetNGlyc等搜索软件分析确定其中76种为糖蛋白,分析发现在血清中质量浓度仅为0.00001 g/L的 β -2-glycoprotein 1也得到了鉴定,表明我们发展的磁性纳米粒子与凝集素相结合的方式,可以高效地富集复杂体系中与主要蛋白成分含量相差12个数量级的低丰度糖蛋白。  相似文献   

2.
Gemcitabine is widely used against a variety of solid tumors; however, it possesses some important drawbacks such as rapid deamination leading to short biological half-life and induction of tumor resistance. We have shown previously that the covalent coupling of squalene (a precursor of cholesterol in sterol biosynthesis) to gemcitabine resulted in a potent nanomedicine, squalenoyl gemcitabine (SQdFdC), which displayed appreciable anticancer activity. Now, the present study describes the concept of magnetic responsiveness of SQdFdC nanoparticles obtained by the nanoprecipitation of SQdFdC around magnetite nanoparticles. To investigate these new core/shell nanoparticles, we have compared their structure, chemical composition and surface properties with those of either the magnetic core alone or of the SQdFdC coating material. X-ray diffraction and infrared spectroscopy studies have shown that the composite core/shell particles displayed an intermediate behavior between that of pure magnetite and of pure SQdFdC nanoparticles, whereas dark-field, high-resolution transmission electron microscopy allowed clear demonstration of the core/shell structure. Electrophoresis measurements as a function of both pH and ionic strength, as well as thermodynamic consideration, showed similar behavior of core/shell and pure SQdFdC nanoparticles, suggesting again the coating of the magnetite core by the SQdFdC prodrug. The two important parameters to be controlled in the efficient adsorption of SQdFdC onto magnetite nanocores were the magnetite/SQdFdC weight ratio and the pluronic F-68 concentration. Pluronic F-68 was found to play a key role as a surfactant in the generation of stable composite core/shell nanoparticle suspensions. Finally, the characterization of the magnetic properties of these core/shell nanoparticles revealed that if the squalenoyl shell reduced the magnetic responsiveness of the particles, it kept unchanged their soft ferrimagnetic character. Thus, the heterogeneous structure of these nanoparticles could confer them both magnetic field responsiveness and potential applicability as a drug carrier for active targeting to solid tumors.  相似文献   

3.
In this study, temperature-responsive magnetite/polymer nanoparticles were developed from iron oxide nanoparticles and poly(ethyleneimine)-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has an approximately 20 nm magnetite core and an approximately 40 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (51.34 emu/g) at room temperature. The most attractive feature of the nanoparticles is their temperature-responsive volume-transition property. DLS results indicated that their average hydrodynamic diameter underwent a sharp decrease from 45 to 25 nm while evaluating the temperature from 20 to 35 degrees C. The temperature-dependent evolution of the C-O stretching band in the FTIR spectra of the aqueous nanoparticles solution revealed that thermo-induced self-assembly of the immobilized block copolymers occurred on the magnetite solid surfaces, which is accompanied by a conformational change from a fully extended state to a highly coiled state of the copolymer. Consequently, the copolymer shell could act as a temperature-controlled "gate" for the transit of guest substance. The uptake and release of both hydrophobic and hydrophilic model drugs were well controlled by switching the transient opening and closing of the polymer shell at different temperatures. A sustained release of about 3 days was achieved in simulated human body conditions. In primary mouse experiments, drug-entrapped magnetic nanoparticles showed good biocompatibility and effective therapy for spinal cord damage. Such intelligent magnetic nanoparticles are attractive candidates for widespread biomedical applications, particularly in controlled drug-targeting delivery.  相似文献   

4.
In this work, we describe an experimental investigation on the colloidal stability of suspensions of three kinds of particles, including magnetite, poly(lactic acid) (PLA), and composite core/shell colloids formed by a magnetite core surrounded by a PLA shell. The experiments were performed with dilute suspensions, so that recording the optical absorbance with time gives a suitable indication of the aggregation and sedimentation of the suspensions. The method allowed us to distinguish very accurately between the different surface and magnetic forces responsible for the structures acquired by particle aggregates. Thus, the pure PLA suspensions are very sensitive to ionic strength and almost unaffected by pH changes. On the contrary, the stability of magnetite systems is mainly controlled by pH. The effect of vertical magnetic fields on the stability of magnetite and magnetite/PLA suspensions is also investigated. The PLA shell reduces the magnetic responsiveness of magnetite, but it is demonstrated that the mixed particles can also form structures induced by the field, despite their lower magnetization, and they can be considered in magnetically targeted biomedical applications.  相似文献   

5.
The local symmetry and local magnetic properties of 6 nm‐sized, bimetallic, cyanide‐bridged CsNiCr(CN)6 coordination nanoparticles 1 and 8 nm‐sized, trimetallic, CsNiCr(CN)6@CsCoCr(CN)6 core–shell nanoparticles 2 were studied by X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD). The measurements were performed at the NiII, CoII, and CrIII L2,3 edges. This study revealed the presence of distorted NiII sites located on the particle surface of 1 that account for the uniaxial magnetic anisotropy observed by SQUID measurements. For the core–shell particles, a combination of the exchange anisotropy between the core and the shell and the pronounced anisotropy of the CoII ions is the origin of the large increase in coercive field from 120 to 890 Oe on going from 1 to 2 . In addition, XMCD allows the relative orientation of the magnetic moments throughout the core–shell particles to be determined. While for the bimetallic particles of 1 , alignment of the magnetic moments of CrIII ions with those of NiII ions leads to uniform magnetization, in the core–shell particles 2 the magnetic moments of the isotropic CrIII follow those of CoII ions in the shell and those of NiII ions in the core, and this leads to nonuniform magnetization in the whole nanoobject, mainly due to the large difference in local anisotropy between the CoII ions belonging to the surface and the NiII ions in the core.  相似文献   

6.
In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems.  相似文献   

7.
A facile and effective approach to preparation of dual‐responsive magnetic core/shell composite microspheres is reported. The magnetite(Fe3O4)/poly(methacrylic acid) (PMAA) composite microspheres were synthesized through encapsulating γ‐methacryloxypropyltrimethoxysilane (MPS)‐modified magnetite colloid nanocrystal clusters (MCNCs) with crosslinked PMAA shell. First, the 200‐nm‐sized MCNCs were fabricated through solvothermal reaction, and then the MCNCs were modified with MPS to form active vinyl groups on the surface of MCNCs, and finally, a pH‐responsive shell of PMAA was coated onto the surface of MCNCs by distillation‐precipitation polymerization. The transmission electron microscopy (TEM) and vibrating sample magnetometer characterization showed that the obtained composite microspheres had well‐defined core/shell structure and high saturation magnetization value (35 emu/g). The experimental results indicated that the thickness and degree of crosslinking of PMAA shell could be well‐controlled. The pH‐induced change in size exhibited by the core/shell microspheres reflected the PMAA shell contained large amount of carboxyl groups. The carboxyl groups and high saturation magnetization make these microspheres have a great potential in biomolecule separation and drug carriers. Moreover, we also demonstrated that other magnetic polymeric microspheres, such as Fe3O4/PAA, Fe3O4/PAM, and Fe3O4/PNIPAM, could be synthesized by this approach. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.  相似文献   

8.
Filtration is an established water‐purification technology. However, due to low flow rates, the filtration of large volumes of water is often not practical. Herein, we report an alternative purification approach in which a magnetic nanoparticle composite is used to remove organic, inorganic, microbial, and microplastics pollutants from water. The composite is based on a polyoxometalate ionic liquid (POM‐IL) adsorbed onto magnetic microporous core–shell Fe2O3/SiO2 particles, giving a magnetic POM‐supported ionic liquid phase (magPOM‐SILP). Efficient, often quantitative removal of several typical surface water pollutants is reported together with facile removal of the particles using a permanent magnet. Tuning of the composite components could lead to new materials for centralized and decentralized water purification systems.  相似文献   

9.
具有核壳结构磁性复合微球的制备与表征   总被引:2,自引:0,他引:2  
龚涛  汪长春 《高分子学报》2008,(11):1037-1042
采用两步法制备了具有核壳结构的Fe3O4/P(MMA/DVB)(core)-P(St/GMA/DVB)(shell)磁性复合微球.首先,用改进的细乳液聚合制备了Fe3O4/P(MMA/DVB)微球;然后,加入总量不同的苯乙烯(St)、甲基丙烯酸缩水甘油酯(GMA)和二乙烯基苯(DVB),通过种子乳液聚合,制备了不同磁含量的核壳结构的磁性复合微球.分别用X-射线衍射(XRD)、高倍透射电镜(HR-TEM)、热重分析(TGA)、振动样品磁力计(VSM)等手段对磁性微球的性能进行了表征.实验结果表明,Fe3O4/P(MMA/DVB)微球的磁含量为84 wt%;通过改变加入壳层单体的量,核壳复合微球的磁含量可控在20 wt%~76 wt%之间.该微球具有超顺磁性,相应的饱和磁化强度为12~50Am2/kg.  相似文献   

10.
We synthesize and characterize stimuli-sensitive core/shell particles with functional group (or material) localized in the core. We previously reported two types of hybrid particles prepared by using the template particles which were synthesized by soap-free emulsion copolymerization with N-isopropylacrylamide and glycidyl methacrylate (GMA) as monomers but by different preparation methods. GMA has advantages in immobilizing materials having several functional groups such as thiol ones. In this study, to obtain the suitable template particles for immobilizing any inorganic nanoparticles in the core, we investigated the effect of feed ratio of the two monomers. Obtained template particles were modified by thiol compounds to introduce ionic groups. They were characterized by dynamic light scattering and scanning electron microscopy. After in situ synthesis of magnetic nanoparticles in the templates, the hybrid particles were characterized directly by transmission electron microscopy. Consequently, we could obtain the hybrid core/shell particles which contained a large amount of magnetic nanoparticles (∼33 wt%) in the core.  相似文献   

11.
Magnetic poly(methyl methacrylate) (PMMA)/poly(methyl methacrylate‐co‐methacrylic acid) [P(MMA–MAA)] composite polymer latices were synthesized by two‐stage soapless emulsion polymerization in the presence of magnetite (Fe3O4) ferrofluids. Different types and concentrations of fatty acids were reacted with the Fe3O4 particles, which were prepared by the coprecipitation of Fe(II) and Fe(III) salts to obtain stable Fe3O4 ferrofluids. The Fe3O4/polymer particles were monodisperse, and the composite polymer particle size was approximately 100 nm. The morphology of the magnetic composite polymer latex particles was a core–shell structure. The core was PMMA encapsulating Fe3O4 particles, and the shell was the P(MMA–MAA) copolymer. The carboxylic acid functional groups (COOH) of methacrylic acid (MAA) were mostly distributed on the surface of the composite polymer latex particles. Antibodies (anti‐human immunoglobulin G) were then chemically bound with COOH groups onto the surface of the magnetic core–shell composite latices through the medium of carbodiimide to form the antibody‐coated magnetic latices (magnetic immunolatices). The MAA shell composition of the composite latex could be adjusted to control the number of COOH groups and thus the number of antibody molecules on the magnetic composite latex particles. With a magnetic sorting device, the magnetic immunolatices derived from the magnetic PMMA/P(MMA–MAA) core–shell composite polymer latex performed well in cell‐separation experiments based on the antigen–antibody reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1342–1356, 2005  相似文献   

12.
Magnetic silica‐coated magnetite (Fe3O4) sub‐microspheres with immobilized metal‐affinity ligands are prepared for protein adsorption. First, magnetite sub‐microspheres were synthesized by a hydrothermal method. Then silica was coated on the surface of Fe3O4 particles using a sol–gel method to obtain magnetic silica sub‐microspheres with core‐shell morphology. Next, the trichloro(4‐chloromethylphenyl) silane was immobilized on them, reacted with iminodiacetic acid (IDA), and charged with Cu2+. The obtained magnetic silica sub‐microspheres with immobilized Cu2+ were applied for the absorption of bovine hemoglobin (BHb) and the removal of BHb from bovine blood. The size, morphology, and magnetic properties of the resulting magnetic micro(nano) spheres were investigated by using scanning microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and a vibrating sample magnetometer (VSM). The measurements showed that the magnetic sub‐microspheres are spherical in shape, very uniform in size with a core‐shell, and are almost superparamagnetic. The saturation magnetization of silica‐coated magnetite (Fe3O4) sub‐microspheres reached about 33 emu g?1. Protein adsorption results showed that the sub‐microspheres had a high adsorption capacity for BHb (418.6 mg g?1), low nonspecific adsorption, and good removal of BHb from bovine blood. This opens a novel route for future applications in removing abundant proteins in proteomic analysis.  相似文献   

13.
The properties of polymer-coated magnetite nanoparticles, which have the potential to be used as effective magnetic resonance contrast agents, have been studied. The magnetite particles were synthesized by using continuous synthesis in an aqueous solution. The polymer-coated magnetite nanoparticles were synthesized by seed precipitation polymerization of methacrylic acid and hydroxyethyl methacrylate in the presence of the magnetite nanoparticles. The particle size was measured by laser light scattering. It was shown that the particle size, variance, magnetic properties, and stability of aqueous magnetite colloidal dispersion strictly depend on the nature of the stabilizing agent. The average hydrodynamic radius of the magnetite particles was found to be 5.7 nm in the stable aqueous colloidal dispersion. An inclusion of the magnetite particle into a hydrophilic polymeric shell increases the stability of the dispersion and decreases the influence of the stabilizing agent on the magnetic and structural properties of the magnetite particles as was shown by X-ray diffraction and M?ssbauer and IR spectroscopy, as well as by vibrating sample magnetometry. The variation in the polymeric shell size and the polymer net density can be useful tools for evaluation of the polymer-coated magnetite particles as effective contrast agents. Copyright 1999 Academic Press.  相似文献   

14.
We prepared core–shell polymer–silsesquioxane hybrid microcapsules from cage‐like methacryloxypropyl silsesquioxanes (CMSQs) and styrene (St). The presence of CMSQ can moderately reduce the interfacial tension between St and water and help to emulsify the monomer prior to polymerization. Dynamic light scattering (DLS) and TEM analysis demonstrated that uniform core–shell latex particles were achieved. The polymer latex particles were subsequently transformed into well‐defined hollow nanospheres by removing the polystyrene (PS) core with 1:1 ethanol/cyclohexane. High‐resolution TEM and nitrogen adsorption–desorption analysis showed that the final nanospheres possessed hollow cavities and had porous shells; the pore size was approximately 2–3 nm. The nanospheres exhibited large surface areas (up to 486 m2 g?1) and preferential adsorption, and they demonstrated the highest reported methylene blue adsorption capacity (95.1 mg g?1). Moreover, the uniform distribution of the methacryloyl moiety on the hollow nanospheres endowed them with more potential properties. These results could provide a new benchmark for preparing hollow microspheres by a facile one‐step template‐free method for various applications.  相似文献   

15.
Three-component microspheres containing an SiO(2)-coated Fe(3)O(4) magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres display three-dimensional core-shell architecture with flowerlike morphology, large surface area (83 m(2)/g), and uniform mesochannels (4.3 nm). The Ni(2+) cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 μg/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivity of the Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres for the His-tagged protein were retained over several separation cycles. Therefore, this work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.  相似文献   

16.
Manipulation of the self‐assembly of magnetic colloidal particles by an externally applied magnetic field paves a way toward developing novel stimuli responsive photonic structures. Using microradian X‐ray scattering technique we have investigated the different crystal structures exhibited by self‐assembly of core–shell magnetite/silica nanoparticles. An external magnetic field was employed to tune the colloidal crystallization. We find that the equilibrium structure in absence of the field is random hexagonal close‐packed (RHCP) one. External field drives the self‐assembly toward a body‐centered tetragonal (BCT) structure. Our findings are in good agreement with simulation results on the assembly of these particles.  相似文献   

17.
Sub-micron sized polystyrene particles containing magnetite more than 30 wt.% were prepared by miniemulsion polymerization with commercially available ferricolloid. The effects of some water-soluble initiators and/or oil-soluble initiators on the particles characteristics, such as the size, morphology, magnetic properties and colloidal stability, were studied. The size of monomer droplets/polymer particles increased from 60 to 300 nm during polymerization, keeping magnetic in core when potassium persulfate (KPS) or ammonium persulfate (APS) was used as the sole initiator. These particles were easily separated from the medium within short time scale in external magnetic field, while such characteristics were controlled by the amount of persulfate used for the polymerization. In contrast, when 2,2′-azobis isobutyronitrile (AIBN) was used as the initiator, the size of droplets/particles was retained to be 90 nm at the most and magnetite nanoparticles located at the surface of polystyrene particles, which were so colloidally stable that they were not separated in external magnetic field. The above-mentioned effect of initiators on particle size in persulfate system was likely originated from the decrease of pH value and the increase of ionic strength, which induced the fusion of droplets/particles containing magnetite. Mixed-initiators system resulted in intermediate characteristics, compared with each initiator system. The location of magnetite in the particle seems to depend on where initiation/polymerization occurred in each initiator system.  相似文献   

18.
Star‐like amphiphilic triblock copolymers were rationally designed and synthesized by combining two sequential atom‐transfer radical polymerization reactions with a click reaction. Subsequently, a family of uniform magnetic/plasmonic core/shell nanoparticles was crafted by capitalizing on these triblock copolymers as nanoreactors. The diameter of the magnetic core and the thickness of the plasmonic shell could be independently and accurately controlled by varying the molecular weights (i.e., the chain lengths) of the inner and intermediate blocks of the star‐like triblock copolymers, respectively. The surface plasmonic absorption of core/shell nanoparticles with different core diameters and shell thicknesses was systematically studied and theoretically modeled. This robust strategy provides easy access to a large variety of multifunctional nanoparticles with large lattice mismatches for use in optics, optoelectronics, catalysis, or bioimaging.  相似文献   

19.
In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms: pure monomers' mixture (monomer addition), and pre-emulsified monomers (pre-emulsion addition). Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.  相似文献   

20.
In this paper, a novel large dimension poly(n-butyl acrylate)-poly(methyl methacrylate-itaconic acid) (PBA-P(MMA-ITA)) core-shell latex particles (CSR) with diameter of 200 nm~300 nm were successfully synthesized via pre-emulsion and semi-continuous seeded emulsion polymerization process. The analysis on the surface tension and coagulation rate of polymeric system, size and distribution of latex particles indicated that the composite emulsifier of sodium dodecyl sulfonate/polyoxyethylene nonyl phenyl ether (SDS/OP-10) had the best emulsified effect. The optimal ratio of SDS/OP-10 was 1:1 and its optimum dosage was 1.0% of monomer amount. FTIR analysis results confirmed that ITA participated in the copolymerization reaction and the chemical bond between P(MMA-ITA) copolymer and PBA core existed in the interfacial of core and shell. DSC analysis results showed that the glass transition temperature (T g) of P(MMA-ITA) copolymer increased with the increase of the ITA dosage and decreased with the increase of the core shell mass ratio. TEM images revealed that CSR particles had core-shell morphology indeed, but the particles’ core-shell morphology would be changed at higher ITA dosage and core shell mass ratio. The size of CSR particles was 330 nm, and the diameter of PBA core was 290 nm. ITA content in the shell of CSR particles was analyzed by non-aqueous acid-base titration. ITA content was the highest at 6% of ITA dosage, ITA amount which chemically bonded with PBA core was the highest at 8% of ITA dosage. When the core shell mass ratio was 60/40, ITA content and ITA amount which grafted onto PBA core were both the highest. ITA content of CSR particles achieved above 1.11% in this work, and it is completely possible for using CSR particles toughening and compatibilizing polyamide 6 (PA 6).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号