Influence of DS of CMC on morphology and performance of magnetic microcapsules

In this paper, we present a reproducible method for the preparation of mixed colloidal nanoparticles, consisting of a magnetic Fe₃O₄ nanoparticle nucleus and a biocompatible self-assembly shell of substitution of sodium carboxy methyl cellulose and chitosan in different degree. The heterogeneous structure of the particles can confer them both the possibility of being used as drug delivery systems and the responsiveness to external magnetic fields, allowing a selective guidance of drug molecules to specific target tissues without a concurrent increase in its level in healthy tissues. The preparation method is based on a coordination and layers by layers self-assembly process. In order to specify that A complete physicochemical characterization of the composite particles is carried out, in order to use this preliminary investigation to show that the CMC/CS shell efficiently coating Fe₃O₄ nanoparticles, and leading to composite particles, the magnetic behavior of the core/shell particles is similar to that of bare magnetic Fe₃O₄ nanoparticles. It is observed that The magnetic microspheres with CMC DS 1.05 served as shell show the best dispersion, super paramagnetic, the range of magnetic field the particles can respond is an order of magnitude higher than others, and the specific saturation magnetization intensity is the highest. Thus we can indicate with the conclusion that if the DS of CMC becomes higher, the Fe₃O₄@CS/CMC would be more sensitive with the extant magnetic field. However, when the DS of CMC is higher than 1.1, the specific saturation magnetization intensity of magnetic microspheres would fall down again and the geometry becomes not well. Therefore, when the DS of CMC stay in 1.05, it would be a better material of magnetic microsphere.     

Monodispers and Multifunctional Magnetic Composite Core Shell Microspheres for Demulsification Applications

Iron oxide@Poly(Glycidylmethacrylate‐methyl methacrylate‐divinyl benzene) magnetic composite core shell microspheres Fe₃O₄@P(GMA‐MMA‐DVB) with epoxy group on the surface was designed and synthesized by solvothermal process followed by distillation polymerization. The surface epoxy group was modified with amino group of ethylene diamine (EDA) to prepare Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ microspheres, and then effects of modification on the structure, interfacial behavior and hence demulsification of the amino modified epoxy coating were examined. The prepared magnetic microspheres were characterized using a laser particle size analyzer, transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. Fourier transform infrared spectrometer analysis indicates the presence of epoxy group, amino group and Fe₃O₄ in the final Fe₃O₄@P(GMA‐MMA‐DVB) and Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ magnetic core shell microspheres. Our experimental results show that Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ magnetic core shell microspheres exhibit good interfacial and demulsification properties and able to remove emulsified water from stable emulsion. The resulting microspheres showed excellent magnetic properties and further these can be recycled and reused by magnetic separation.     

Fabrication of 1D Fe3O4/P(NIPAM-MBA) thermosensitive nanochains by magnetic-field-induced precipitation polymerization

One-dimensional (ID) magnetic thermosensitive Fe₃O₄/poly(N-isopropylacrylamide–N,N′-methylenebisacrylamide) (P(NIPAM-MBA)) peapod-like nanochains have been successfully synthesized by magnetic-field-induced precipitation polymerization using Fe₃O₄ as building blocks and P(NIPAM-MBA) as linker. Fe₃O₄ microspheres can be arranged with the direction of an external magnetic field in a line via the dipolar interaction between Fe₃O₄ microspheres and linked permanently via P(NIPAM-MBA) coating during precipitation polymerization. 1D magnetic Fe₃O₄/P(NIPAM-MBA) peapod-like nanochains can be oriented and aligned along the direction of the external magnetic field. More interestingly, Fe₃O₄ microspheres in each peapod were regularly arranged in a line and periodically separated through the P(NIPAM-MBA) layers with a visible interparticle spacing.     

Double‐Layered Plasmonic–Magnetic Vesicles by Self‐Assembly of Janus Amphiphilic Gold–Iron(II,III) Oxide Nanoparticles

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double‐layered plasmonic–magnetic vesicle assembled from Janus amphiphilic Au‐Fe₃O₄ NPs grafted with polymer brushes of different hydrophilicity on Au and Fe₃O₄ surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au‐Fe₃O₄ NPs in opposite direction, and the orientation of Au or Fe₃O₄ in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers.     

Preparation of composite magnetic microspheres by reactive blending

A novel method for preparation of polymer-based magnetic microspheres was proposed by utilizing melt reactive blending,which was based on selective location of Fe_3O_4 nanoparticles in PA6 domains of polystyrene(PS)/polyamide 6 (PA6) immiscible blends.The morphology of PA6/Fe_3O_4 composite magnetic microspheres was studied by scanning electronic microscopy(SEM).The composite magnetic microspheres were spherical with a diameter range of 0.5-8μm;the diameter was sharply decreased with a very narrow distri...     

Synthesis and characterization of amino-functionalized single magnetic core–silica shell composites

The thermal decomposition approach, reverse micro-emulsion system and surface modification technique had been successfully used to synthesis single magnetic core Fe₃O₄@Organic Layer@SiO₂–NH₂ complex microspheres. The magnetization of the magnetic microspheres core could be easily tuned between 28 and 56 emu/g by adjusting the amount of 2-mercaptobarbituric acid. It was found that the Organic Layer to some extent had a protective effect on avoiding Fe₃O₄ being oxidized into Fe₂O₃. Each Fe₃O₄@Organic Layer microsphere could be coated uniformly by about 30 nm of silica shell. The average diameter of the Fe₃O₄@Organic Layer@SiO₂ composites was about 538 nm. The saturation magnetization of the Fe₃O₄@Organic Layer@SiO₂ complex microspheres was 12.5% less than magnetic microspheres cores. The Fe₃O₄@Organic Layer@SiO₂–NH₂ composites possessed a huge application potentiality in specificity enriching and separating biological samples.     

免疫磁性纳米微球的制备与表征

成功制备了Fe3O4磁性纳米颗粒及二甲基丙烯酸乙二醇酯-甲基丙烯酸(EGDMA-MAA)共聚物包覆的Fe3O4磁性复合微球。将吲哚美辛抗体固定在复合微球表面,形成了Fe3O4(核)/聚合物-抗体(壳)的复合免疫磁性颗粒。XRD结果表明,制备的Fe3O4的晶型为反立方尖晶石型且纯度较高;TEM表征表明Fe3O4粒径较为均匀,平均粒径为12nm;磁性复合微球的平均直径为460nm。制备的Fe3O4磁性纳米颗粒和磁性复合微球有较强的磁响应强度,其饱和磁化率分别为49.16和8.38emu/g,能够满足磁性分离的要求。FT IR验证了磁性复合微球中羧基特征峰的存在,表明羧基成功连接在磁性微球上面。通过碳二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)活化法将微球表面羧基活化并成功与抗吲哚美辛抗体交联。     

Hierarchical Fe3O4@TiO2 Yolk–Shell Microspheres with Enhanced Microwave‐Absorption Properties

A facile and efficient strategy for the synthesis of hierarchical yolk–shell microspheres with magnetic Fe₃O₄ cores and dielectric TiO₂ shells has been developed. Various Fe₃O₄@TiO₂ yolk–shell microspheres with different core sizes, interstitial void volumes, and shell thicknesses have been successfully synthesized by controlling the synthetic parameters. Moreover, the microwave absorption properties of these yolk–shell microspheres, such as the complex permittivity and permeability, were investigated. The electromagnetic data demonstrate that the as‐synthesized Fe₃O₄@TiO₂ yolk–shell microspheres exhibit significantly enhanced microwave absorption properties compared with pure Fe₃O₄ and our previously reported Fe₃O₄@TiO₂ core–shell microspheres, which may result from the unique yolk–shell structure with a large surface area and high porosity, as well as synergistic effects between the functional Fe₃O₄ cores and TiO₂ shells.     

One‐pot synthesis of composite microspheres with core‐shell structure

One‐pot synthesis of thermoresponsive magnetic composite microspheres with a poly(N‐isopropylacrylamide) (PNIPAM) shell and a Fe₃O₄ core is demonstrated. Temperature sensitivity of PNIPAM was adopted to design the novel synthesis pathway. The as‐prepared composite microspheres have an obvious core‐shell structure with a mean size of approximately 250 nm. The Fe₃O₄ core is approximately 5 nm and the thickness of the PNIPAM shell is approximately 10 nm. The content of Fe₃O₄ in the composite microspheres can be controlled by this method. The composite microspheres experience a swelling and shrinking process in water by adjusting the temperature below and above the lower critical solution temperature (LCST) around 32 °C. These microspheres also show fine response to an external magnetic field. This work presents a platform to synthesize organic/inorganic composite microspheres in a facile and efficient approach. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2702–2708     

Double-Layered Plasmonic–Magnetic Vesicles by Self-Assembly of Janus Amphiphilic Gold–Iron(II,III) Oxide Nanoparticles

Janus nanoparticles (JNPs) offer unique features, including the precisely controlled distribution of compositions, surface charges, dipole moments, modular and combined functionalities, which enable excellent applications that are unavailable to their symmetrical counterparts. Assemblies of NPs exhibit coupled optical, electronic and magnetic properties that are different from single NPs. Herein, we report a new class of double-layered plasmonic–magnetic vesicle assembled from Janus amphiphilic Au-Fe₃O₄ NPs grafted with polymer brushes of different hydrophilicity on Au and Fe₃O₄ surfaces separately. Like liposomes, the vesicle shell is composed of two layers of Au-Fe₃O₄ NPs in opposite direction, and the orientation of Au or Fe₃O₄ in the shell can be well controlled by exploiting the amphiphilic property of the two types of polymers.     

Phosphate-functionalized magnetic microspheres for immobilization of Zr ions for selective enrichment of the phosphopeptides

In this work, we developed phosphate functionalized magnetic Fe₃O₄@C microspheres to immobilize Zr⁴⁺ ions for selective extraction and concentration of phosphopeptides for mass spectrometry analysis. Firstly, we synthesized Fe₃O₄@C magnetic microspheres as our previous work reported. Then, the microspheres were functionalized with phosphate groups through a simple hydrolysis reaction using 3-(trihydroxysilyl)propyl methylphosphate. And the Zr⁴⁺ ions were immobilized on phosphate-functionalized magnetic microspheres by using phosphate chelator. Finally, we successfully employed Zr⁴⁺-phosphate functionalized magnetic microspheres to selectively isolate the phosphopeptides from tryptic digests of standard protein and real samples including rat brain. All the experimental results demonstrate the enrichment efficiency and selectivity of the method we reported here.     

Hydrophilic dual‐responsive magnetite/PMAA core/shell microspheres with high magnetic susceptibility and ph sensitivity via distillation‐precipitation polymerization

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.     

Preparation of magnetic Fe3O4/TiO2/Ag composite microspheres with enhanced photocatalytic activity

The novel three-component Fe₃O₄/TiO₂/Ag composite mircospheres were prepared via a facile chemical deposition route. The Fe₃O₄/TiO₂ mircospheres were first prepared by the solvothermal method, and then Ag nanoparticles were anchored onto the out-layer of TiO₂ by the tyrosine-reduced method. The as-prepared magnetic Fe₃O₄/TiO₂/Ag composite mircospheres were applied as photocatalysis for the photocatalytic degradation of methylene blue. The results indicate that the photocatalytic activity of Fe₃O₄/TiO₂/Ag composite microspheres is superior to that of Fe₃O₄/TiO₂ due to the dual effects of the enhanced light absorption and reduction of photoelectron–hole pair recombination in TiO₂ with the introduction of Ag NPs. Moreover, these magnetic Fe₃O₄/TiO₂/Ag composite microspheres can be completely removed from the dispersion with the help of magnetic separation and reused with little or no loss of catalytic activity.     

Study on Fe3O4/polyaniline electromagnetic composite hollow spheres prepared against sulfonated polystyrene colloid template

Fe₃O₄/polyaniline (PANI) composite hollow spheres were prepared by using sulfonated polystyrene (SPS) microspheres as templates. The sulfonic acid groups were applied to induce absorbing Fe₃O₄ nanoparticle, and subsequently, conductive PANI was grown. Finally, the polystyrene cores were selectively dissolved to yield composite hollow microspheres with electromagnetic properties. The analysis results indicated that the adsorption of Fe₃O₄ on template core by electrostatic interaction resulted in magnetic composite microspheres. The conductivity of composite hollow spheres was remarkably increased after polyvinylpyrrolidone modification which favored the growth of PANI on SPS/Fe₃O₄ and enhanced the integrity of hollow microspheres. The saturated magnetization of the composite hollow microspheres was tuned from 2.7 to 9.1 emu/g, and the conductivity was in the range from 10^?2 to 10⁰?S/cm.     

Preparation of core–shell structure Fe3O4@SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His‐tag protein purification

The core–shell structure Fe₃O₄/SiO₂ magnetic microspheres were prepared by a sol–gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu²⁺, Ni²⁺ and Zn²⁺, were chelated on the Fe₃O₄@SiO₂–IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni²⁺‐chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe₃O₄@SiO₂–IDA–Ni²⁺ magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His‐tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Fabricating and Tailoring Polyaniline (PANI) Nanofibers with High Aspect Ratio in a Low‐Acid Environment in a Magnetic Field

In a 0.010 m HCl solution, we successfully transformed irregular polyaniline (PANI) agglomerates into uniform PANI nanofibers with a diameter of 46–145 nm and a characteristic length on the order of several microns by the addition of superparamagnetic Fe₃O₄ microspheres in a magnetic field. The PANI morphological evolution showed that the PANI nanofibers stemmed from the PANI coating shell synthesized on the surface of the Fe₃O₄ microsphere chains. It was found that the magnetic field could optimize the PANI nanofibers with a narrow diameter size distribution, and effectively suppressed secondary growth. When compared with other microspheres (like silica and polystyrene), only the use of superparamagnetic Fe₃O₄ microspheres resulted in the appearance of PANI nanofibers. Attempts to form these high‐quality PANI nanofibers in other concentrations of HCl solution were unsuccessful. This deficiency was largely attributed to the inappropriate quantity of aniline cations.     

Magnetic Silica‐Coated Sub‐Microspheres with Immobilized Metal Ions for the Selective Removal of Bovine Hemoglobin from Bovine Blood

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.     

A novel poly(deep eutectic solvent)-based magnetic silica composite for solid-phase extraction of trypsin

Novel poly(deep eutectic solvent) grafted silica-coated magnetic microspheres (Fe₃O₄@SiO₂-MPS@PDES) were prepared by polymerization of choline chloride-itaconic acid (ChCl-IA) and γ-MPS-modified magnetic silica composites, and were characterized by vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectra (XPS), thermal gravimetric analysis (TGA) and transmission electron microscope (TEM). Then the synthetic Fe₃O₄@SiO₂-MPS@PDES microspheres were applied for the magnetic solid-phase extraction (MSPE) of trypsin for the first time. After extraction, the concentration of trypsin in the supernatant was determined by a UV–vis spectrophotometer. Single factor experiments were carried out to investigate the effects of the extraction process, including the concentration of trypsin, the ionic strength, the pH value, the extraction time and the temperature. Experimental results showed the extraction capacity could reach up to 287.5 mg/g under optimized conditions. In comparison with Fe₃O₄@SiO₂-MPS, Fe₃O₄@SiO₂-MPS@PDES displayed higher extraction capacity and selectivity for trypsin. According to the regeneration studies, Fe₃O₄@SiO₂-MPS@PDES microspheres can be recycled six times without significant loss of its extraction capacity, and retained a high extraction capacity of 233 mg/g after eight cycles. Besides, the activity studies also demonstrated that the activity of the extracted trypsin was well retained. Furthermore, the analysis of real sample revealed that the prepared magnetic microspheres can be used to purify trypsin in crude bovine pancreas extract. These results highlight the potential of the proposed Fe₃O₄@SiO₂-MPS@PDES-MSPE method in separation of biomolecules.     

Preparation and characterization of a magnetic microsphere synthesized from sucrose allyl ether for transcatheter arterial embolization

The polymerization of allyl monomers has been reported as notoriously difficult because of degradative chain transfer induced by the allyl radical as a primary radical with resonance-stabilized structure. A favorable approach is to produce polymers from inert monomers by using photodriven radical–mediated cyclization reaction (PRMC). In this study, Fe₃O₄ at sucrose allyl ether (Fe₃O₄@SAE) magnetic microspheres with sucrose as the skeleton and encapsulated nanomagnetic particles was prepared by PRMC. Its morphology and performance were characterized by using microscope, infrared, thermogravimetric and differential scanning calorimetry, scanning electron microscope/energy-dispersive spectrometer, and vibrating sample magnetometer. The feasibility as an embolic agent was evaluated by catheter transportability and cell compatibility. The results show that Fe₃O₄@SAE (sucrose allyl ether) magnetic microspheres have an average particle size of 371 μm, regular spherical shape, good dispersion, basically non-toxicity, and good cell compatibility. It has a certain degree of magnetism and can use alternating magnetic fields to achieve targeted embolization.     

Fe3O4/PEI/Au@CdSe/CdS多功能复合材料的制备与表征

以共沉淀法制备出Fe₃O₄纳米粒子,通过聚乙烯亚胺(PEI)修饰Fe₃O₄纳米粒子,再原位复合上Au纳米粒子,制得Fe₃O₄/PEI/Au纳米颗粒微球。再将Fe₃O₄/PEI/Au纳米颗粒与巯基乙酸修饰的量子点CdSe/CdS连接,成功制备了Fe₃O₄/PEI/Au@CdSe/CdS多功能复合微球。经过傅里叶变换红外光谱仪(FTIR)、荧光分光光度计、荧光显微镜、X射线衍射(XRD)、透射电子显微镜(TEM)及振动样品磁强计(VSM)的表征。结果表明:多功能复合微球的粒径在40 nm左右,具有超顺磁性,剩磁,矫顽力近似等于零,饱和磁化强度为28.83 A·m²·kg^-1,同时兼有优越的荧光性能和金纳米粒子的特性。