Synthesis, characterization, and intracellular uptake of carboxyl-terminated poly(amidoamine) dendrimer-stabilized iron oxide nanoparticles

We report the synthesis and characterization of a group of carboxyl-functionalized poly(amidoamine) (PAMAM) dendrimers of generation 3 (G3) that were used for the stabilization of superparamagnetic iron oxide (Fe(3)O(4)) nanoparticles (NPs). Folic acid (FA) molecules were conjugated onto the dendrimer surfaces in an attempt to achieve specific targeted imaging of tumor cells that overexpress FA receptors using dendrimer-stabilized Fe(3)O(4) NPs. Fe(3)O(4) NPs were synthesized using controlled co-precipitation of Fe(ii) and Fe(iii) ions and the formed dendrimer-stabilized Fe(3)O(4) NPs were characterized using transmission electron microscopy (TEM) and polyacrylamide gel electrophoresis (PAGE). The intracellular uptake of dendrimer-stabilized Fe(3)O(4) NPs was tested in vitro using KB cells (a human epithelial carcinoma cell line) that overexpress FA receptors. It appears that carboxyl-terminated PAMAM dendrimer-stabilized Fe(3)O(4) NPs can be uptaken by KB cells regardless of the repelling force between the negatively charged cells and the negatively charged particles. In the presence of a large amount of carboxyl terminal groups on the dendrimer surface, the receptor-mediated endocytosis of Fe(3)O(4) NPs stabilized by FA-modified dendrimers was not facilitated. It implies that the surface charge of dendrimer-stabilized magnetic iron oxide NPs in biological medium is an important factor influencing their biological performance.     

Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.     

Synthesis of Fe3O4@SiO2-Ag magnetic nanocomposite based on small-sized and highly dispersed silver nanoparticles for catalytic reduction of 4-nitrophenol

We demonstrate a single-step facile approach for the synthesis of glycine (amino acid) passivated Fe(3)O(4) magnetic nanoparticles (GMNPs) using soft chemical route. The surface passivation of Fe(3)O(4) nanoparticles with glycine molecules was evident from infrared spectroscopy, thermal and elemental analyses, and light scattering measurements. These nanoparticles show better colloidal stability, good magnetization, excellent self-heating capacity under external AC magnetic field and cytocompatibility with cell lines. Further, the active functional groups (-NH(2)) present on the surface of Fe(3)O(4) nanoparticles can be accessible for routine conjugation of biomolecules/biolabelling through well-developed bioconjugation chemistry. Specifically, a new colloidal glycine passivated biocompatible Fe(3)O(4) nanoparticles with excellent specific absorption rate (SAR) have been fabricated, which can be used as an effective heating source for hyperthermia treatment of cancer (thermal therapy).     

磁性纳米粒子负载钯催化有机合成反应研究进展

磁性纳米粒子负载钯催化的有机合成反应,由于具有催化活性高,催化剂在外加磁场作用下即可快速分离和重复使用等特点,已引起了人们的广泛关注.综述了近年来磁性纳米粒子负载钯催化有机合成反应的研究进展,载体包括Fe3O4纳米粒子、有机小分子修饰的磁性纳米粒子、SiO2包覆的磁性纳米粒子、碳修饰磁性纳米粒子、羟基磷灰石包覆的磁性纳米粒子和有机高分子修饰的磁性纳米粒子等.     

Fe_3O_4/CdTe/聚氨酯纳米复合物的制备及其性能研究

由共沉淀法和Stober法制备了伯胺基功能化SiO2稳定的Fe3O4磁性纳米粒子Fe3O4@SiO2-NH2;Fe3O4@SiO2-NH2与二异氰酸酯及咪唑阳离子二醇、聚乙二醇的反应使其表面形成阳离子型聚氨酯稳定层;通过阳离子型聚氨酯与CdTe量子点表面修饰的巯基乙酸间的电荷相互作用,制备得到了Fe3O4/CdTe/聚氨酯纳米复合物.用X射线衍射(XRD)、红外吸收光谱(FTIR)、热重分析(TGA)、透射电子显微镜(TEM)、磁强计(VSM)、紫外吸收光谱(UV)、荧光发射光谱(PL)表征了该纳米复合物的结构与性能.结果表明,CdTe量子点均匀地分散在Fe3O4@SiO2磁性纳米粒子周围,所得纳米复合物在溶剂中分散均匀,不团聚,且具有超顺磁性,并保持了CdTe量子点的荧光性能.     

Preparation and characterization of thermosensitive polymers grafted onto silica-coated iron oxide nanoparticles

In this study, multifunctional nanoparticles containing thermosensitive polymers grafted onto the surfaces of 6-nm monodisperse Fe(3)O(4) magnetic nanoparticles coated by silica were synthesized using reverse microemulsions and free radical polymerization. The magnetic properties of SiO(2)/Fe(3)O(4) nanoparticles show superparamagnetic behavior. Thermosensitive PNIPAM (poly(N-isopropylacrylamide)) was then grafted onto the surfaces of SiO(2)/Fe(3)O(4) nanoparticles, generating thermosensitive and magnetic properties of nanocomposites. The sizes of fabricated nanoparticles with core-shell structure are controlled at about 30 nm and each nanoparticle contains only one monodisperse Fe(3)O(4) core. For thermosensitivity analysis, the phase transition temperatures of multifunctional nanoparticles measured using DSC was at around 34-36 degrees C. The magnetic characteristics of these multifunctional nanoparticles were also superparamagnetic.     

Iron oxide coated gold nanorods: synthesis, characterization, and magnetic manipulation

We report a simple process to generate iron oxide coated gold nanorods. Gold nanorods, synthesized by our three-step seed mediated protocol, were coated with a layer of polymer, poly(sodium 4-styrenesulfonate). The negatively charged polymer on the nanorod surface electrostatically attracted a mixture of aqueous iron(II) and iron(III) ions. Base-mediated coprecipitation of iron salts was used to form uniform coatings of iron oxide nanoparticles onto the surface of gold nanorods. The magnetic properties were studied using a superconducting quantum interference device (SQUID) magnetometer, which indicated superparamagnetic behavior of the composites. These iron oxide coated gold nanorods were studied for macroscopic magnetic manipulation and were found to be weakly magnetic. For comparison, premade iron oxide nanoparticles, attached to gold nanorods by electrostatic interactions, were also studied. Although control over uniform coating of the nanorods was difficult to achieve, magnetic manipulation was improved in the latter case. The products of both synthetic methods were monitored by UV-vis spectroscopy, zeta potential measurements, and transmission electron microscopy. X-ray photoelectron spectroscopy was used to determine the oxidation state of iron in the gold nanorod-iron oxide composites, which is consistent with Fe2O3 rather than Fe3O4. The simple method of iron oxide coating is general and applicable to different nanoparticles, and it enables magnetic field-assisted ordering of assemblies of nanoparticles for different applications.     

Sonochemical formation of iron oxide nanoparticles in ionic liquids for magnetic liquid marble

Ionic liquids (ILs)-stabilized iron oxide (Fe(2)O(3)) nanoparticles were synthesized by the ultrasonic decomposition of iron carbonyl precursors in [EMIm][BF(4)] without any stabilizing or capping agents. The Fe(2)O(3) nanoparticles were isolated and characterized by X-ray powder diffraction, transmission electron microscopy and susceptibility measurements. The physicochemical properties of ILs containing magnetic Fe(2)O(3) nanoparticles (denoted as Fe(2)O(3)@[EMIm][BF(4)]), including surface properties, density, viscosity and stability, were investigated in detail and compared with that of [EMIm][BF(4)]. The Fe(2)O(3)@[EMIm][BF(4)] can be directly used as magnetic ionic liquid marble by coating with hydrophobic and unreactive polytetrafluoroethylene (PTFE), for which the effective surface tension was determined by the puddle height method. The resulting magnetic ionic liquid marble can be transported under external magnetic actuation, without detachment of magnetic particles from the marble surface that is usually observed in water marble.     

磁性Fe_3O_4@PS@PAMAM-Ag复合催化粒子的制备及其可再生催化性能(英文)

采用聚苯乙烯(PS)包裹Fe3O4磁性纳米粒子,制得Fe3O4@PS复合微球,以此作为磁性载体,通过微球表面的羧基将聚酰胺-胺类树形大分子(PAMAM)连接到磁性载体上,然后使Ag纳米粒子镶嵌在树形分子层中,制得可再生的金属复合催化粒子Fe3O4@PS@PAMAM-Ag.并采用红外光谱、扫描电镜、电感耦合等离子体质谱(ICP-MS)和X射线光电子能谱等方法对复合催化粒子进行了表征,结果表明,树形分子可以较好地分散和稳定金属Ag纳米粒子,所制复合催化粒子表面Ag含量为1.64%,具有较高的催化还原对硝基苯酚的活性.同时,利用外加磁场可以方便快捷地从反应体系中分离出来,继续用于下一次反应中,复合催化粒子循环使用6次后,仍保持完全的催化性能.     

磁场诱导沉淀聚合制备一维Fe3O4/P（MAA-DVB）纳米链

采用溶剂热法制备了单分散Fe3O4纳米粒子,以甲基丙烯酸（MAA）和二乙烯基苯（DVB）为聚合单体,在沉淀聚合过程中通过磁场诱导自组装制备了一维高磁响应性永久连接的Fe3O4/P（MAA-DVB）纳米链.采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射仪（XRD）,热重分析（TGA）及振动样品磁强计（VSM）等对其形貌、磁含量和磁响应性等进行了分析表征.结果表明,该法制备的一维Fe3O4/P（MAA-DVB）纳米链的磁含量为91%时,其比饱和磁化强度为72emu/g.在外磁场存在条件下,一维Fe3O4/P（MAA-DVB）纳米链将按外界磁场的方向取向.此外,每个豆荚内的Fe3O4纳米粒子规则的排列在一条线上,并通过P（MAA-DVB）聚合物使其均匀分布.     

磁性聚苯胺纳米微球的合成与表征

报道了具有核壳结构的Fe3O4-聚苯胺磁性纳米微球的合成方法和表征结果.微球同时具有导电性和磁性能.在优化的实验条件下,可得到饱和磁化强度Ms为55.4 emu/g,矫顽力Hc为62 Oe的磁性微球.微球的导电性随着微球中Fe含量的增加而下降.微球的磁性能则随着Fe含量的增加而增大.Fe3O4磁流体的粒径和磁性聚苯胺微球的粒径均在纳米量级.纳米Fe3O4粒子能够提高复合物的热性能.实验表明,磁流体和聚苯胺之间可能存在着一定的相互作用,但这种相互作用较为复杂,难于研究     

磁性Fe_3O_4-聚吡咯纳米微球的合成与表征

报道了具有核壳结构的Fe3O4 聚吡咯磁性纳米微球的合成方法和表征结果 .微球同时具有导电性和磁性能 .在优化的实验条件下 ,可得到饱和磁化强度为 2 3 4emu g ,矫顽力为 45 2Oe的磁性微球 .微球的导电性随着微球中Fe3O4含量的增加而下降 .微球的磁性能则随着Fe3O4含量的增加而增大 .Fe3O4磁流体的粒径和磁性聚吡咯微球的粒径均在纳米量级 .纳米Fe3O4粒子能够提高复合物的热性能 .实验表明 ,磁流体和聚吡咯之间存在着一定的相互作用 ,正是这种相互作用使磁性聚吡咯纳米微球的热稳定性提高 .     

PREPARATION AND CHARACTERIZATION OF DOXORUBICIN-LOADED MAGNETIC ANTICANCER NANOPARTICLES

Doxorubicin（ADM）-loaded magnetic anticancer nanoparticles, using Fe3O4 as core, doxorubicin as model drug and polyvinylpyrrolidone （PVP） as matrix, were prepared by inverse emulsion polymerization. The experimental results showed that the average diameter of Fe3O4 particles was 19.8nm. The X-ray diffraction itzdicated that the prepared Fe3O4 particle was pure cubic Fe3O4, The results obtained by SEM showed the magnetic nanoparticles under optimal operating condition had a smooth spherical surface, LLS showed an average size of 78. 7nm. And IR results demonstrated that they consisted of ADM, PVP and Fe3O4.     

新型磁性荧光Fe3O4-CdSe纳米复合材料的制备

以1-十八烯作为高沸点溶剂, 在磁性粒子表面沉积量子点获得新型的磁性荧光Fe₃O₄-CdSe 纳米异质结构. 首先以乙酰丙酮铁(Fe(acac)₃)为前驱体, 二苯醚为溶剂, 油酸为表面活性剂和油胺(OAm)为表面活性剂兼还原剂, 通过溶剂热法制备单分散性的Fe₃O₄ 纳米粒子. 然后以1-十八烯为高沸点溶剂, CdO 为镉源,TOP-Se为硒源, 十六胺为表面活性剂以及硬脂酸为生长促进剂和成核剂制备得到新型的Fe₃O₄-CdSe纳米异质结构. 通过透射电镜(TEM), 傅里叶变换红外(FTIR)光谱, X射线衍射(XRD)谱, X射线光电子能谱(XPS)分析仪, 振动样品磁强计(VSM), 紫外-可见(UV-Vis)光谱和光致发光(PL)等手段对Fe₃O₄-CdSe 纳米复合材料的结构和性能进行表征. 结果表明, CdSe纳米粒子成功地吸附在Fe₃O₄纳米粒子表面, 并沿着c轴生长, 形成了宽3.6 nm, 长分别为14.5 和32.5 nm的新型枣核状和钉子状的异质结构体. 这种新型的Fe₃O₄-CdSe纳米复合材料是由磁铁矿Fe₃O₄和六方形的CdSe棒状结构组成, 具有较好的荧光性能和超顺磁性. 随着CdSe棒长度的增加, 荧光吸收峰向长波方向移动. Fe₃O₄纳米粒子, 枣核状和钉子状的Fe₃O₄-CdSe纳米复合材料的饱和磁化强度分别是57.80, 40.76和31.10 emu·g^-1.     

Variable on-demand release function of magnetoresponsive hybrid capsules

Magnetoresponsive hybrid capsules formed with polyelectrolytes, amphiphile bilayers and Fe(3)O(4) nanoparticles were fabricated by a colloid-templating technique. Melamine-formaldehyde (MF) core particles with polyelectrolyte multilayer shell were prepared by layer-by-layer assembly. Fe(3)O(4) nanoparticles were additionally deposited on the capsular surface. Hollow capsules were obtained by the removal of the MF core particles. Amphiphile bilayer was finally coated on the obtained hollow capsules. The deposition amount of the Fe(3)O(4) nanoparticles is variable by changing the concentration of Fe(3)O(4) dispersion using for preparation of capsules. Encapsulated dyes were released on-demand by irradiation with an alternating magnetic field, due to a phase transition in the amphiphile membrane, induced by heating of the magnetic nanoparticles. The release rate of the hybrid capsules was controllable through controlling the deposition amount of Fe(3)O(4) nanoparticles on the capsules.     

Facile synthesis of hierarchical core-shell Fe3O4@MgAl-LDH@Au as magnetically recyclable catalysts for catalytic oxidation of alcohols

A novel core-shell structural Fe(3)O(4)@MgAl-LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl-LDH surface of Fe(3)O(4)@MgAl-LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.     

Luminescent polymer microcapsules addressable by a magnetic field

The simultaneous encapsulation of both luminescent semiconductor and magnetic oxide nanoparticles in polymer microcapsules is demonstrated for the first time. Highly luminescent CdTe semiconductor nanocrystals serve as luminescent markers, while magnetic Fe3O4 nanoparticles allow external manipulation of the capsules by magnetic field. The method introduced is general enough to allow the fabrication of different types of multifunctional capsules in a similar way. The use of multifunctional water-compatible capsules introduced in this paper for the controlled release and directed drug delivery in biological systems is envisaged.     

壳核型磁性纳米纤维素微球的超声制备及表征

A kind of cellulose magnetic nanoparticle with a core / shell structure has been prepared by ultrasonic irradiation. Cellulose acts as the shell while Fe3O4 magnetic nanoparticles take the role as the core. Magnetic force microscopy（MFM）with atomic force microscopy（AFM）measurement showed that the size of the magnetic nanoparticles is about 30-50 nm in diameter,while the Fe3O4 core is about 20-30 nm. FT-IR,XRD and MFM was used to provide the chemical and magnetic information of the nanoparticles. The MFM image showed that the nanoparticles separate very well with each other,indicating the cellulose shell produces a good prevention from the aggregation of the Fe3O4 particles. MFM studies also showed two magnetic nanoparticles can form particle-pairs,indicating a weak magneto-dipole interaction between magnetic nanoparticles. It is also found that the average sizes of magnetic nanoparticles have relation to the power of ultrasonic irradiation,and the possible mechanism is discussed.     

Luminescent and magnetic Fe3O4/Py/PAM nanocomposites for the chromium(VI) determination

A novel luminescent and magnetic Fe(3)O(4)/pyrene/polyacrylamide (Fe(3)O(4)/Py/PAM) nanocomposite has been prepared under ultrasonic radiation. This magnetic nanocomposite combined with pyrene would lead to a special functional magnetic luminescent composite that enjoys both the advantages of magnetic nanoparticles of Fe(3)O(4) and fluorescence nanoparticles of pyrene. Taking advantage of the magnetic property of Fe(3)O(4) nanocomposites, we can separate Fe(3)O(4)/Py/PAM nanocomposites from solution easily just by using a permanent magnet. Based on the fluorescence quenching of Fe(3)O(4)/Py/PAM nanocomposites by Cr(VI), a method for the selective determination of Cr(VI), without separation of Cr(III) in water, was developed. Under optimal experimental conditions, a limit of detection of 0.01 microg mL(-1) was achieved. The calibration curve was linear over the concentration range of 0.1-14.0 microg mL(-1) with a correlation coefficient of 0.9975. The proposed method has been applied to the selective quantification of Cr(VI) in synthetic samples and wastewater samples with the satisfactory results.     

Synthesis and characterization of bracelet-like magnetic nanorings consisting of Ag-Fe3O4 bi-component nanoparticles

Stable bracelet-like magnetic nanorings, formed by Ag-Fe(3)O(4) nanoparticles with an average size around 40 nm, have been successfully prepared in large scale by means of reducing Ag(+) and Fe(3+) simultaneously under mild conditions. In the reaction, tiny grains of silver are used as seeds to prompt small Fe(3)O(4) nanoparticles to grow larger, which is essential to enhance the magnetic dipole-dipole interactions, while only superparamagnetic Fe(3)O(4) nanoparticles (about 10 nm in size) can be obtained in the absence of Ag seeds. The XRD, TEM, SAED and the EDS line scan data reveal that these nanoparticles are in the core-shell structure. These magnetic Ag-Fe(3)O(4) nanoparticles assembled into nanorings by magnetic dipole-dipole interactions with a diameter of 100-200 nm. The saturation magnetization of the nanorings is 39.5 emu g(-1) at room temperature. The MRI images indicate that these kind of nanorings have the potential application in diagnostics as a T(2) MRI contrast agent.