超顺磁单分散性Fe_3O_4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.

纳米材料-Fe_3O_4磁性纳米粒

纳米科学是一个正在蓬勃发展的学科,它的发展对其他科学领域都有重要的影响,其中有一大领域的纳米粒子已经近被人们广泛研究,Fe_3O_4磁性纳米粒就是其中较为典型的一个代表。它在构建生物传感器、光学传感器、电化学传感器等领域都有重要的应用。

纳米Fe_3O_4-TiO_2靶向光动力疗法对肝癌细胞的杀伤效应（英文）

光动力疗法(PDT)作为一种迅速发展的传统替代疗法,在抗癌治疗中显示出巨大的潜力。为增强靶向性和提高光催化杀伤效率,本研究设计了一种新型光敏剂Fe_3O_4-Ti O_2磁性纳米粒。在不同外磁场下,考察其在可见光和紫外光激发下对肝癌细胞的杀伤效应。同时利用流式细胞术检测纳米Fe_3O_4-Ti O_2对肝癌细胞凋亡率、细胞周期和线粒体膜电位的影响。根据纳米Fe_3O_4-Ti O_2和肝癌细胞的作用方式探讨其抗癌机制。结果表明,可见光激发纳米Fe_3O_4-Ti O_2可以杀伤癌细胞,且其杀伤效率与紫外光激发下无明显差别。此外,Fe_3O_4-Ti O_2比Ti O_2具有更高的细胞摄取率,从而使其具有更高的选择性和光催化杀伤效率。其作用机制是光催化纳米Fe_3O_4-Ti O_2产生活性氧ROS抑制癌细胞,然后通过阻滞细胞周期G_0/G_1期,降低线粒体膜电位,线粒体去极化,最终诱导细胞凋亡。

Folate-conjugated Fe_3O_4 nanoparticles for in vivo tumor labeling

Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging （MRI） target detection and magnetic hyperthermia.

Alginate-Coated Fe3O4 Hollow Microspheres for Drug Delivery

Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, and then grafting alginate onto the surface of amine magnetic. The hollow structure of Fe3O4 spheres was characterized by TEM, XRD, and XPS. The M-H hysteresis loop indicated that the magnetic spheres exhibit snperparamagnetic characteristics at room temperature. Daunorubicin acting as a model drug was loaded into the carrier, and the maximum percent of envelop and load were 28.4% and 14.2% respectively. The drug controlled releasing behaviors of the carriers were compared in different pH media.

Preparation and Analysis of Fe3O4 Magnetic Nanoparticles Used as Targeted-drug Carriers

Fe3O4 magnetic nanoparticles were prepared by the aqueous co-precipitation of FeCl3-6H2O and FeCl2-4H2O with addition of ammonium hydroxide. The conditions for the preparation of Fe3O4 magnetic nanoparticles were optimized, and Fe3O4 magnetic nanoparticles obtained were characterized systematically by means of transmission electron microscope （TEM）, dynamic laser scattering analyzer （DLS） and X-ray diffraction （XRD）. The results revealed that the magnetic nanoparticles were cubic shaped and dispersive, with narrow size distribution and average diameter of 11.4 nm. It was found that the homogeneous variation of pH value in the solution via the control on the dropping rate of aqueous ammonia played a critical role in size distribution. The magnetic response of the product in the magnetic field was also analyzed and evaluated carefully. A 32.6 mT magnetic field which is produced by four ferromagnets was found to be sufficient to excite the dipole moments of 0.05 g Fe3O4 powder 2 cm far away from the ferromagnets. In conclusion, the Fe3O4 magnetic nanoparticles with excellent properties were competent for the magnetic carders of targeted-drug in future application.

Static magnetic field-assisted synthesis of Fe3O4 nanoparticles and their adsorption of Mn(Ⅱ) in aqueous solution

A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD,TEM,SEM,VSM and BET.The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe_3O_4 nanoparticles but improved the crystallinity.The morphology of Fe_3O_4 nanoparticles was varied from random spherical particles to rod-like cluster structure.The VSM results indicated that the saturation magnetization value of the Fe_3O_4 nanoparticles was significantly improved by the magnetic field.The BET of Fe_3O_4nanoparticles prepared with the magnetic field was larger than the control by 23.5%.The batch adsorption experiments of Mn(Ⅱ) on the PMF and AMF Fe_3O_4 nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased.At pH 8,the Mn(Ⅱ) adsorption capacity for the PMF and AMF Fe_3O_4 was reached at 36.81 and 28.36 mg·g^(-1),respectively.The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe_3O_4.The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(Ⅱ) from aqueous solution.

Fabrication of Poly（y-glutamic acid）-coated Fe3O4 Magnetic Nanoparticles and Their Application in Heavy Metal Removal

In this study, poly（y-glutamic acid）-coated Fe3O4 magnetic nanoparticles （y-PGA/Fe304 MNPs） were successfully fabricated using the co-precipitation method. Fe3O4 MNPs were also prepared for comparison. The av erage size and specific surface area results reveal that 7-PGA/Fe304 MNPs （52.4 nm, 88.41 m2.g-1） have smaller particle size and larger specific surface area_ than Fe3O4 MNPs （62.0 nm, 76.83 mLg-1）. The y-PGA/Fe3O4 MNPs

Surface Modfication of Fe_3O_4 Nanoparticles

Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.

Synthesis of size-controllable Fe3O4 magnetic submicroparticles and its biocompatible evaluation in vitro

Large scaled uniform and size-controllable magnetic submicroparticles(MSPs) were synthesized via solvothermal method with ferric chloride as iron source and sodium acetate as trapping agent. The influence of Fe^(3+) and Na Ac contents on the size distribution of MSPs was investigated. The structural and morphological properties of the synthesized particles were studied by scanning electron microscopy(SEM), X-ray power diffraction(XRD) and vibrating sample magnetometer(VSM). The well-dispersed MSPs with size of 100-1000 nm were obtained by simply adjusting the contents of Fe^(3+) and NaA c. In addition, the hemolysis and cytotoxicity of Fe_3O_4 MSPs, and their ability to case arrest in cell life-cycles were studied. The results indicate that larger size could lead to lower hemolysis. From MTT(3-(4,5-dimethylthuazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the interactions between MSPs and adhesive mouse fibroblast cell line(L929) were probed. Larger size of Fe_3O_4 MSPs demonstrates lower cell viability following an exposure to the cells.

The structure and properties of Fe_3O_4/P (NaUA-St-BA) magnetic composite nano particles

Fe3O4/P （NaUA-St-BA） core-shell composite micro spheres were in situ prepared by soapless polymerization of styrene and butyl acrylate, with Fe3O4magnetic colloidal particles coated with NaUA. The results of IR and XRD analysis demonstrated that the desired polymer chains have been covalently bonded to the surface of Fe3O4 nano particles. The morphology analysis by TEM confirmed that the composite particles have the core-shell structure and a relatively uniform diameter of about 100nm. The magnetic properties of the obtained composite latex particles were measured by VSM and found that they exhibited super paramagnetic properties. Finally, the prepared magnetic composite particles latex is stable for several months.

磁性纳米介导的pcDNA3．1(＋)-p53对HepG2细胞的作用

目的探讨氨基硅烷化Fe3O4磁性纳米介导的pcDNA3.1(+)-p53质粒(-p53质粒)对人肝癌HepG2细胞的作用。方法(1)以-p53质粒作为表达基因,用氨基硅烷化Fe3O4磁性纳米粒进行细胞转染,计算转染率,并与脂质体转染组,空白载体组及空白对照组进行比较。(2)观察在外加磁场条件下的氨基硅烷化Fe3O4磁性纳米粒的转染效率和速度。(3)观察-p53磁性纳米粒对HepG2细胞生长增殖的抑制作用。结果(1)RT-PCR及Westernblot检测证实,载有氨基硅烷化Fe3O4的磁性纳米粒能成功的在人肝癌HepG2细胞中导入了外源性的野生型p53基因,其转运效率(39%)略高于相同条件下脂质体的转染效率(36%)(P>0.05)。(2)在外加磁场条件下氨基硅烷化Fe3O4磁性纳米粒的转染效率明显增强。(3)转染的外源性p53基因可明显抑制人肝癌HepG2细胞的生长速度及集落形成能力,使细胞阻滞于G1期,抑制率为46%。结论(1)氨基硅烷化Fe3O4纳米颗粒是良好的基因转运载体,可将外源性基因成功的转入靶细胞。(2)转入外源性野生型p53能有效抑制HepG2细胞的生长增殖。该研究为基因治疗恶性肿瘤的在体实验奠定了基础。

苦参碱磁性缓释颗粒的制备及性能研究

目的制备苦参碱磁性缓释颗粒,并对其性能进行研究。方法以壳聚糖、Fe3O4纳米粒为主要材料,采用L9(34)正交试验法优选制备工艺,并评价其性能。结果正交设计获最优处方为:微晶纤维素质量0.40 g,壳聚糖浓度2.0%,壳聚糖质量0.25 g,磁性纳米粒质量为0.12 g,药物体外释放行为符合一级动力学方程,并具有明显的磁敏感性。结论该制剂制备工艺合理可行,有较好的缓释效果和顺磁性,可作为消化系肿瘤治疗的给药剂型。

E1A基因对裸鼠移植瘤细胞凋亡及Survivin、Caspase-3基因表达的影响

目的探讨E1A基因对裸鼠移植瘤肿瘤细胞凋亡的影响及其相关作用机制。方法采用免疫组织化学染色检测E1A基因对裸鼠移植瘤肿瘤细胞凋亡及Survivin基因和Caspase-3基因表达的影响。结果免疫组织化学染色显示:E1A基因组肿瘤细胞凋亡数量较多,Caspase-3基因呈高表达,Survivin基因表达较弱;而Hela和Hela-vect组肿瘤细胞凋亡数量较少,Survivin基因呈高表达,Caspase-3基因表达较弱。结论E1A基因能够明显促进裸鼠移植瘤肿瘤细胞的凋亡,该作用可能与E1A基因激活Caspase-3基因和抑制Survivin基因的表达有关。

Effective Approach for the Synthesis of Monodisperse Magnetic Nanocrystals and M-Fe3O4 （M = Ag, Au, Pt, Pd） Heterostructures

Monodisperse and size-tunable magnetic iron oxide nanoparticles （NPs） have been synthesized by thermal decomposition of an iron oleate complex at 310 ℃ in the presence of oleylamine and oleic acid. The diameters of the as-synthesized iron oxide NPs decrease with increasing concentrations of iron oleate complex and oleic acid/oleylamine. In addition, the size-dependent crystallinity and magnetic properties of iron oxide NPs are presented. It is found that larger iron oxide NPs have a higher degree of crystallinity and saturation magnetization. More importantly, various M-iron oxide heterostructures （M = Au, Ag, Pt, Pd） have been successfully fabricated by using the same synthesis procedure. The iron oxide NPs are grown over the pre-made metal seeds through a seed-mediated growth process. The physicochemical properties of Au-Fe3O4 heterostructures have been characterized by X-ray diffraction （XRD）, superconducting quantum interference device （SQUID） magnetometry and UV-vis spectroscopy. The as-synthesized Au-Fe3O4 heterostructures show a red-shift in surface plasmon resonance peak compared with Au NPs and similar magnetic properties to Fe3O4 NPs. The heterojunction effects present in such nanostructures offer the opportunity to tune the irphysicochemical properties. Therefore, this synthesis process can be regarded as an efficient way to fabricate a series of heterostructures for a variety of applications.

Development of a novel nano-biosorbent for the removal of fluoride from water

The study was designed to investigate the use of two sorbents namely(i) Fe3O4 nanoparticles immobilized in sodium alginate matrix(FNPSA) and(ii) Fe3O4 nanoparticles and saponified orange peel residue immobilized in sodium alginate matrix(FNPSOPR) as sorbents for fluoride removal from contaminated water. The synthesized nanoparticles were analyzed and characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, and scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier transform-infrared spectrometry. The sorbent matrices were prepared in the form of beads and surface functionalized to enable enhanced sorption of fluoride ions. Batch sorption studies were carried out and the sorption isotherm and reaction kinetics were analyzed. Both the sorbents followed Langmuir model of isotherm and fitted well with Pseudo first order reaction. The maximum sorption capacity exhibited by FNPSA and FNPSOPR was58.24 mg·g-1and 80.33 mg·g-1respectively. Five sorption–desorption cycles exhibited 100%, 97.56%, 94.53%,83.21%, and 76.53% of regeneration of FNPSOPR. Accordingly, it is demonstrated that FNSOPR could be used as a promising sorbent for easy and efficient removal of fluoride from contaminated water with good reusability.The current work suggests a simple and effective method to remove fluoride from contaminated water.

Synthesis of monodispersed Fe3O4@C core/shell nanoparticles

We report a facile method to synthesize dispersed Fe304@C nanoparticles （NPs）. Fe304 NPs were firstly prepared via the high temperature diol thermal decomposition method. Fe304@C NPs were fabricated using glucose as a carbon source by hydro- thermal process. The obtained products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, vibrating sample magnetometer （VSM） and Raman spectra. The results indicate that the original shapes and magnetic property of Fe304 NPs can be well preserved. The magnetic particles are well dispersed in the carbon matrix. This strategy would provide an efficient approach for existing applications in Li-ion batteries and drug delivery. Meanwhile, it offers the raw materials to assemble future functional nanometer and micrometer superstructures.

Chemical synthesis, structure and magnetic properties of Co nanorods decorated with Fe_3O_4 nanoparticles

Magnetic anisotropic nanocomposites have attracted tremendous interests, due to their unexpected properties originating from the interactions of the interfaces except for the intrinsic features. In this work, we develop a facile solution chemistry synthesis method to prepare the one-dimensional(1 D) Co-Fe3O4 heterostructures with hard magnetic property. Interestingly, the Fe precursor firstly decompose and nucleate individually, and then grow on the surface of the hexagonal closed-packed(hcp) Co nanorods(NRs) upon prolonging heating time at higher temperature, which is different from the general seed-mediated growth model. The distribution density of Fe3O4 nanoparticles(NPs) on the surface of the Co NRs can be varied with the addition of Fe source,modulating the values of coercivity and saturation magnetization for the Co-Fe3O4 heterostructures. The as-synthesized Co-Fe3O4 heterostructures maintain the hard magnetic properties with a coercivity value more than 2.5 kOe as well as a saturation magnetization value up to 128.3 emu g-1, indicating the preservation of the anisotropy of the hcp Co NRs.

Magnetic control： Switchable ultrahigh magnetic gradients at Fe3O4 nanoparticles to enhance solution-phase mass transport

Enhancing mass transport to electrodes is desired in almost all types of electrochemical sensing, electrocatalysis, and energy storage or conversion. Here, a method of doing so by means of the magnetic gradient force generated at magnetic-nanoparticle-modified electrodes is presented. It is shown using Fe3O4-nanoparticle-modified electrodes that the ultrahigh magnetic gradients （〉10^8 T·m^- 1） established at the magnetized Fe3O4 nanoparticles speed up the transport of reactants and products at the electrode surface. Using the Fe（Ⅲ）/ Fe（Ⅱ）-hexacyanoferrate redox couple, it is demonstrated that this mass transport enhancement can conveniently and repeatedly be switched on and off by applying and removing an external magnetic properties of magnetite nanoparticles field, owing to the superparamagnetic Thus, it is shown for the first time that magnetic nanoparticles can be used to control mass transport in electrochemical systems. Importantly, this approach does not require any means of mechanical agitation and is therefore particularly interesting for application in micro- and nanofluidic systems and devices.

Investigation of Influence of Magnetic Nanoparticles on the Quality-Factor of the Oscillatory Circuit

In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.