Controllable preparation of magnetic polymer nanospheres with high saturation magnetization by miniemulsion polymerization

Magnetic Fe₃O₄/poly(styrene-co-acrylamide) core/shell nanospheres were prepared by one-step miniemulsion polymerization in the presence of Fe₃O₄ ferrofluids. The functional monomer of acrylamide was used not only to modify the surface of the nanospheres with functional groups, but also to form modified bilayer with SDBS to control the encapsulation and particle size of nanospheres. The properties of magnetic nanospheres were characterized by IR, TEM, TG and VSM. The results indicated that the superparamagnetic nanopsheres had small particle size of 60 nm, high saturation magnetization of 27.1 emu/g, high magnetic content and abundant functional groups. The possible formation mechanism of magnetic nanospheres was discussed in detail.     

Magnetic hollow mesoporous silica nanospheres: facile fabrication and ultrafast immobilization of enzymes

Hollow mesoporous silica nanospheres with large pore size of around 11 nm have been synthesized by a structural difference based selective etching strategy, and the highly dispersed hydrophobic Fe3O4 nanoparticles with a particle size of 5 nm were then impregnated into hollow cores of nanospheres through these large pores by a vacuum impregnation technique. The structural characteristics of obtained magnetic composites were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Selected Area Electron Diffraction (SAED), Ultraviolet-visible (UV-Vis) and Vibrating Sample Magnetometer (VSM). The results show that the obtained Fe3O4-hollow mesoporous silica composites exhibit superparamagnetic property with saturation magnetization value of 4.17 emu/g. Furthermore, the obtained supports show ultrafast immobilization of hemoglobin and the immobilized enzymes are not denatured, indicating that the superparamagnetic hollow mesoporous silica spheres are excellent support for immobilization of enzymes with magnetic recycling property.     

The one-pot synthesis of dextran-based nanoparticles and their application in in-situ fabrication of dextran-magnetite nanocomposites

The dextran-based nanoparticles containing carboxyl groups were synthesized by a one-pot approach, without using any organic solvents and surfactants. The resultant dextran-based nanoparticles was used as a host for the growing and organization of Fe(3)O(4) nanoparticles. The approach consists of the mixture of ferrous/ferric ions aqueous solution and host nanoparticles and subsequent coprecipitation of ferrous/ferric ions in basic medium. The magnetic nanocomposite material obtained was characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), X-ray diffraction techniques (XRD) and vibrating sample magnetometry (VSM). The data demonstrate that the carboxyls which can capture cationic ferrous/ferric by electronic interaction in the dextran-based hosts plays a crucial role in fabricating nanocomposites with a homogeneous spatial distribution of magnetite nanoparticles. The magnetic nanocomposites exhibit comparable saturation magnetizations to that of reported Fe(3)O(4) nanoparticles, and therefore display great potential in a large scope of biomedical fields.     

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。     

Preparation and characterization of Ni-nitrilotriacetic acid bearing poly(methacrylic acid) coated superparamagnetic magnetite nanoparticles

Stable superparamagnetic magnetite (Fe3O4) nanoparticles were synthesized via co-precipitation in the presence of poly(methacrylic acid) (PMAA) in aqueous solution. The polymer coated Fe3O4 nanoparticles were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermal analysis, and vibrating sample magnetometry (VSM) techniques. These measurements reveal the presence of magnetite nanoparticles with a size of approximately 8 nm inside the PMAA matrix. The magnetization value of these superparamagnetic nanoparticles at room temperarure and 7 T was measured as about 40 emu/g. PMAA-coated Fe3O4 nanoparticles were further assembled with Ni-chelate through a reaction between a primary amine-bearing NTA (nitrilotriacetic acid) ligand and carboxy-functional groups of PMAA. NTA-PMAA-coated magnetite nanoparticles were then loaded with nickel ions and characterized using FTIR. The average amount of binded Ni on the surface of the NTA-modified PMAA coated Fe3O4 was calculated as 1.65 +/- 0.3 x 10(-6) mol nickel(II) ions per g of the magnetic particles from the inductively coupled plasma optical emission spectroscopy (ICP-OES) measurements.     

微波辐射乳液聚合制备聚氰基丙烯酸正丁酯磁性微球

通过化学共沉淀法制备Fe3O4纳米粒子,再用油酸钠和十二烷基磺酸钠(SDS)对Fe3O4进行改性,制得稳定的水基磁流体。在自制的磁流体存在下,以氰基丙烯酸正丁酯(BCA)为单体,用微波辐射乳液聚合的方法制备了Fe3O4/聚氰基丙烯酸正丁酯磁性微球。并用X射线衍射仪(XRD),透射电子显微镜(TEM),傅立叶红外光谱仪(FT-IR),振动样品磁强计(VSM)对制备的磁性高分子微球的结构形貌和磁性能进行表征测试。结果表明,在适当的pH值条件下,得到了粒径为150 nm~200 nm,饱和磁化强度为20.23 emμ/g,粒径均一的聚氰基丙烯酸正丁酯磁性微球。     

乳液聚合制备Fe3O4／聚（苯乙烯-甲基丙烯磺酸钠）磁性高分子微球

采用甲基丙烯磺酸钠（SMS）为阴离子功能单体,过硫酸钾（KPS）为引发剂,在Fe3O4磁流体的存在下与苯乙烯（st）一起进行乳液聚合,制备了具有磁性Fe3O4为核、St和SMS的共聚物为壳的Fe3O4／聚（St—SMS）磁性高分子复合微球．采用透射电子显微镜（TEM）、动态激光粒度仪（PCS）、傅里叶红外光谱仪（FT—IR）和x射线衍射仪（XRD）对制备的磁性高分子微球的结构形貌进行了表征,用振动样品磁强计（VSM）和热重（TG）分析仪对其磁性能和热性能进行了测试．结果表明,该阴离子型磁性高分子复合微球的最小粒径为185．3nm,最高饱和磁化强度为8．74emu／g．     

纳米Fe3O4/聚苯胺复合粒子的制备及其在交变磁场下的发热性能

用水解沉淀法合成了纳米Fe₃O₄粒子,并在其悬浮液中原位包覆聚苯胺,制备出纳米Fe₃O₄/聚苯胺复合粒子。研究了两种纳米粒子在交变磁场下的发热性能,对它们在定向集热治疗肿瘤中的应用前景进行了评价。纳米Fe₃O₄粒子的粒径为10~30nm,表面包覆聚苯胺后,复合粒子的粒径为30~50nm。纳米Fe₃O₄粒子的比饱和磁化强度为50.05Am2/kg,矫顽力为10.9kA/m;纳米Fe₃O₄/聚苯胺复合粒子的比饱和磁化强度为26.34Am2/kg,矫顽力为0。在10mg/mL的生理盐水悬浮液中,在外加交变磁场作用30min后,纳米Fe₃O₄粒子悬浮液的温度为63.6℃,纳米Fe₃O₄/聚苯胺悬浮液的温度为52.4℃,二者均达到了医学上定向集热治疗肿瘤用热籽的发热要求,是很有应用前景的医用纳米材料。      

Synthesis and Characterization of Dendrimer-Encapsulated Iron and Iron-Oxide Nanoparticles

In this paper, a series of iron (Fe) containing nanoparticles were prepared by employing PAMAM (Poly(amidoamine), dendrimers with different generations (G0?CG3) as templates and sodium borohydride as a reducing agent. The products have been characterized by TEM, FT-IR, XRD, VSM, TGA, and XPS. XRD analysis reveal low crystallinity of formed particles within the dendrimers, however, crystallinity of the nanoparticles was observed to increase with increasing generation of dendrimers. Dominant phases were determined as magnetite (Fe₃O₄ or maghemite, ??-Fe₂O₃). XPS analysis revealed the chemical composition of nanoparticles as iron oxide which indicated the oxidation of Fe species subsequent to the reduction process, in agreement with XRD analysis. The magnetization curves have superparamagnetic nonhysteretic characteristic at lower fields and with nonsaturation characteristic at high fields. Magnetic evaluation of samples with the 20:1?molar ratio of Fe:PAMAM showed decreasing superparamagnetic character and decreasing saturation magnetisation with increasing generation of dendrimers.     

Synthesis and characterization of environment friendly and multifunctional Fe3O4 magnetic nanoparticles

In this study, the size-uniform (5-6 nm), nearly spherical, and well-dispersed aqueous Fe3o4 magnetic nanoparticles were prepared by an improved chemical coprecipitation method. The DDAT-terminated (S-1-Dodecyl-S'-(alpha,alpha'-dimethyl-alpha"-acetic acid) trithiocarbonate) polymethacrylic (PMA-DDAT) was chosen as the apt surfactant, and the terminal DDAT can be used as a high efficient RAFT chain-transfer agent for further functionalization. Then, the functionalized Fe3O4 reacted with 4-amino-2,2,6,6-tetramethyl-piperidine-oxyl (4-NH2-TEMPO) to give the spin labeling magnetic nanoparticles. Finally, the multifunctional MNPs was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), Fourier transform infrared spectrometer (FT-IR), and vibrating-sample magnetometer (VSM). The obtained highly water-soluble, superparamagnetic, and multifunctional magnetic nanoparticles should find potential applications in biomedical research.     

磁性Fe_3O_4@离子印迹聚(MMA-HPMA-DVB)复合材料的合成及其对水中Ni(Ⅱ)选择性吸附

采用超声协助悬浮聚合法以Ni(Ⅱ)离子为模板制备了氨基功能化纳米Fe_3O_4-离子印迹聚(甲基丙烯酸甲酯(MMA)-3-(2-氨基乙基胺)-2-甲基丙烯酸羟丙酯(HPMA)-二乙烯基苯(DVB))磁性复合材料(Fe_3O_4@ion imprinted poly(MMA-HPMA-DVB),Fe_3O_4@IIP(MMA-HPMA-DVB))。通过EA、XRD、FTIR、TEM、VSM等手段对Fe_3O_4@IIP(MMA-HPMA-DVB)的组成、结构、形貌、磁性等进行了表征,并研究了其吸附水中Ni(Ⅱ)的性能。结果表明:合成的Fe_3O_4@IIP(MMA-HPMA-DVB)平均粒径为100nm,饱和磁化强度为43.8emu/g;共聚单体甲基丙烯酸甲酯(MMA)的羰基通过氢键与Fe_3O_4表面羟基结合,有利于Fe_3O_4@IIP(MMA-HPMA-DVB)的核-壳结构的形成与稳定;Fe_3O_4@IIP(MMA-HPMA-DVB)对Ni(Ⅱ)的吸附受溶液pH值影响较小;等温吸附线符合Langmuir模型,饱和吸附量(q_(m,c)=500 mg/g,q_(m,e)=478 mg/g)高于非离子印迹材料(Fe_3O_4@none-ion imprinted poly(MMA-HPMA-DVB),Fe_3O_4@NIP(MMA-HPMA-DVB)),q_(m,c)=90.9mg/g,q_(m,e)=83.8mg/g)。吸附过程可在5min内达到平衡,符合准二级动力学模型。Fe_3O_4@IIP(MMA-HPMA-DVB)能高选择性地有效吸附水中Ni(Ⅱ),对Ni(Ⅱ)的印迹因子(α)为1.9,对几种常见共存离子的选择性因子(β)7.7,是潜在的高选择性吸附和回收Ni(Ⅱ)的功能材料。     

Fe3O4/聚苯乙烯磁性微球的合成与表征

用化学共沉淀法合成了Fe3O4纳米微粒,并用双层表面活性剂对其进行表面修饰,得到了以水和乙醇为分散介质的磁流体。在磁流体的存在下,用改进的乳液聚合方法合成了Fe3O4/聚苯乙烯磁性微球。X射线衍射研究表明,Fe3O4纳米微粒的平均粒径约为10 nm;在透射电镜下观察磁性微球的粒径在140 nm左右;并用红外光谱和热失重方法表征了复合微球的化学成分及其所含Fe3O4的百分数。阐述了双层表面活性剂改性的机理,并对聚合过程中单体、磁流体及引发剂的用量的影响进行了讨论。     

Preparation of iron oxide nanoparticles by microwave synthesis and their characterization

In this study production of fine particle Fe2O3 via microwave processing of Fe(NO3)3.nH2O followed by low temperature annealing was reported. XRD was used to characterize the structural properties of nanoparticles. Approximate particle sizes were between 3-13 nm according to Scherrer's equation. Single point BET measurement results also show that samples have large surface area and they are nanometer sized particles. TEM study was conducted to examine the structure of the nanoparticles. TEM figure is in good agreement with the results obtained from Scherrer's equation using XRD spectra. In order to characterize the magnetic properties of the nanoparticles VSM (Vibrating Sample Magnetometer) was used. From these results it can be concluded that the sample containing only maghemite phase exhibits superparamagnetic behaviour, on the other hand sample containing both hematite and maghemite phases shows paramagnetic behaviour above 300 K, superparamagnetic behavior at lower temperatures.     

微波多元醇法制备单分散Ni1-xZnxFe2O4/MWCNTs与磁性能

以多壁碳纳米管(MWCNTs)为模板,三乙二醇(TREG)为溶剂,采用微波多元醇法制备MWC-NTs负载组成可控的Ni1-xZnxFe2O4(x=0.4、0.5、0.6)纳米复合材料Ni1-xZnxFe2O4/MWCNTs。其结构和形貌通过XRD、SEM、TEM和EDX进行表征,用VSM测试样品的磁性,并探讨了微波功率、微波时间对镍锌铁氧体负载的影响。结果表明立方系尖晶石结构的单分散Ni1-xZnxFe2O4磁性纳米粒子均匀负载在碳纳米管表面,平均粒径约为6nm;其磁性能与镍锌铁氧体的组成有关,随着Zn含量的增加,饱和磁化强度(Ms)先增大后减小,当x=0.5时Ms达到最大值。矫顽力(Hc)都比较小,在室温下表现为超顺磁性。     

超顺磁单分散性Fe3O4磁纳米粒的制备及性能表征

具有超顺磁单分散性的Fe₃O₄磁纳米粒在生物医学材料领域有着广泛的用途. 本研究在水、乙醇和甲苯混合体系74℃回流的条件下制备了具有超顺磁性的表面含油酸的Fe₃O₄磁纳米粒,研究了制备过程中OH^-浓度的变化对磁纳米粒的表面性能、粒径、分散性及磁性能的影响, 并对其机理进行了初步探讨. 采用XRD、FTIR、DLS、TEM和VSM等手段对制备的磁纳米粒进行表征. 结果表明, 当NaOH/Fe(Ⅱ)摩尔比＜8时, Fe₃O₄磁纳米粒表面含油酸可良好地分散于非极性溶剂中, NaOH的加入对磁纳米粒的粒径和饱和磁化强度等性能无明显影响;而当NaOH/Fe(Ⅱ)摩尔比≥8时, Fe₃O₄磁纳米粒仅能分散于水等极性溶剂中, 饱和磁化强度虽可增至40A·m²/kg, 但为多分散且易团聚.     

Magnetic Fe3O4-chitosan micro- and nanoparticles for wastewater treatment

In this study, first, magnetic nanoparticles (MNP) were synthesized using a coprecipitation method and the synthesized particles were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM). According to DLS and VSM analyses results, it was seen that the size of the MNP was smaller than 10?nm and they exhibited superparamagnetic properties, respectively. Then, magnetic Fe₃O₄-chitosan micro/nanoparticles were synthesized using a suspension cross-linking method in the presence of the MNP. Fe₃O₄-chitosan microparticles (Fe₃O₄-CMs) and Fe₃O₄-chitosan nanoparticles (Fe₃O₄-CNs), which have different structural, morphological, and magnetic properties, were obtained. All of the particles were characterized using transmission electron microscopy (TEM), FTIR, TGA, DLS, and VSM. In the second part of the study, the dye adsorption properties of the two different adsorbents from aqueous solution were investigated. For these purposes, Bromothymol Blue (BB) was used as a dye and the parameters affecting adsorption of BB (contact time, initial dye concentration, temperature and pH) were investigated. When the optimum adsorption conditions were provided for each adsorbent, the adsorption capacities of Fe₃O₄-CNs and Fe₃O₄-CMs were 82.2 and 193.3?mg/g, respectively.     

Synthesis and characterization of multifunctional iron oxide nanoparticles

In order to get high water solubility, monodisperse, superparamagnetic nanoparticles, poly (acrylic acid) was employed to modify Fe3O4 by a high-temperature solution-phase hydrolysis approach. Then, folic acid (FA) and fluorescein isothiocyanate were successively conjugated with prepared magnetic nanoparticles (MNPs). The functional MNPs were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscope (TEM), inductively coupled plasma-atomic emission spectrometer (ICP-AES), and vibrating sample magnetometer (VSM), respectively. The toxicity of the materials was evaluated by selecting NIH/3T3 fibroblast cells and no toxic effect was observed. The fluorescent imaging and targeting property of the MNPs were also realized in vitro and in vivo experiments by confocal laser scanning microscopy (CLSM) and Kodak In-Vivo FX Professional Imaging System, respectively. The results indicated that the final products exhibited interesting magnetic, optical and targeting properties for further potential applications in biological and biomedical fields.     

A novel route to prepare Fe3O4/P(MAA-co-NVP) cross-linked magnetic composite microspheres with core-shell architecture by surface-initiated radical dispersion polymerization

A novel route was proposed to design and construct a magnetic composite microsphere with a controllable and regular core-shell architecture, which consists of Fe3O4 nanoparticles chemical-covalently encapsulated with pH-smart poly(methacrylic acid-co-N-vinyl pyrrolidone) (P(MAA-co-NVP)) cross-linked copolymers by a surface-initiated radical dispersion polymerization approach. The multistep surface treatment was employed to improve the dispersity and surface-chemical reactivity of Fe3O4 nanoparticles, involving introduction of active -NH2 groups, coupling of 1,1-methylene bis-(4-isocyanato-cyclohexane) and immobilizing of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide]. The structure and morphological characterization were carried out by FTIR, TEM, SEM and XRD etc. The neat Fe3O4 nanoparticles take on an aggregated spherical shape with an average diameter of about 12 nm, while Fe3O4/P(MAA-co-NVP) magnetic microspheres assume regularly monodispersed spheres with a mean dimension of ca. 0.8 microm. The dimension of the microspheres is abruptly increased with increasing pH values of the media. The microspheres exhibit superparamagnetic properties. It is expected that this type of novel microspheres can be employed as a magnetic targeted and pH-sensitive drug carrier.     

磁性核壳Fe3O4/P(GMA-DVB)-SH-Au复合催化剂的制备及催化性能

首先通过水热法合成了单分散空心Fe3O4磁球,之后利用蒸馏沉淀聚合将P(GMA-DVB)聚合物层包覆在Fe3O4磁球表面形成Fe3O4/P(GMA-DVB)核壳结构,巯基化处理后吸附Au纳米粒子,得到磁性核壳Fe3O4/P(GMA-DVB)-SH-Au复合催化剂。利用TEM,SEM,FTIR,XRD,TGA,VSM及UV-vis对其进行表征,并考察该催化剂在催化还原4-硝基苯酚反应中的催化性能。结果表明合成的材料粒径均匀,球形度规整,核壳结构明显,在催化反应中,Fe3O4/P(GMA-DVB)-SH-Au表现出优异的催化性能,而且经过连续8次循环使用后,催化效率仍可保持80%以上。     

Fe3O4／壳聚糖纳米微球的制备与表征

采用原位聚合法制备分散性良好、粒径在300nm以下、兼具磁性能与荧光性能的Fe3O4／壳聚糖纳米微球,通过XRD、IR和SEM等对产物的组成、结构和微观形貌进行表征,利用荧光光谱分析Fe3O4壳聚糖纳米微球进行光学性能测试,实验结果表明,通过交联反应,Fe3O4被壳聚糖所包覆,产物显示出了非常好的荧光性能,并且在外加磁场下具有明显的磁响应行为。