多肽或转铁蛋白接枝的氧化铁纳米粒子的制备及表征

以聚乙二醇(PEG)为还原剂、溶剂和修饰剂,将乙酰丙酮铁(Fe(acac)_3)高温热分解合成超顺磁性氧化铁纳米粒子(Superparamagnetic iron oxide nanoparticles,SPIONs)。透射电镜(TEM)结果显示:纳米粒子形状规则,分布均匀,平均粒径为7.5±1.0 nm。XRD结果表明样品主相为结晶良好的Fe_3O_4。通过将SPIONs表面修饰的PEG与马来酸酐(Mal)结合,再借助EDC-NHS的方法,分别与多肽(angiopep-2,ANG)或转铁蛋白(transferrin,Tf)接枝。结果表明:修饰ANG的SPIONs的水合动力学粒径为42 nm,zeta电位为-9.9 mV,ANG的修饰量为19 wt%,饱和磁化强度为58emu/g;修饰Tf的SPIONs的水合动力学粒径为96 nm,zeta电位为2.3 mV,Tf的修饰量为10 wt%,饱和磁化强度为43 emu/g。红外分析表明ANG或Tf分别共同修饰在SPIONs表面。修饰物使纳米粒子具有良好了水分散性。本工作为SPIONs应用于生物医学研究建立了材料基础。     

烟碱/磷酸化壳聚糖纳米粒子的制备及理化性质的测定

制备了烟碱/磷酸化壳聚糖纳米粒子水分散液。扫描电镜和激光散射结果表明,在pH值4.0~4.8之间,形成了稳定的烟碱/磷酸化壳聚糖纳米粒子。纳米粒子分散液的pH值从4.0上升到4.8,纳米粒子分散液的Zeta-电位下降。磷酸化壳聚糖和烟碱的体积比从2升至6,烟碱/磷酸化壳聚糖纳米粒子的粒径减小;纳米粒子的粒径随磷酸化壳聚糖溶液浓度的升高而显著增大。烟碱/磷酸化壳聚糖纳米粒子的平均粒径在300 nm~800 nm。随磷酸化壳聚糖和烟碱的质量比增大,烟碱/磷酸化壳聚糖纳米粒子的负载率增大,纳米粒子对烟碱的包封效率可以达到88.8%。     

MPEG修饰的纳米氧化铁粒子的合成及清洗工艺

以MPEG为溶剂、还原剂及修饰剂,Fe(acac)3为铁源,通过高温热分解法制备了超顺磁性氧化铁纳米粒子(SPIONs).采用饱和食盐水清洗方法对合成的粒子进行收集,经透析除去其表面残留的NaCl.采用XRD,TEM,HRTEM,SQUID,ICP MS,TGA,FT IR,纳米粒度与Zeta电位分析仪对样品进行表征.结果表明:经透析处理后氧化铁的质量分数为NaCl的6.9×104倍,制备的SPIONs具有高的结晶度及单分散性,在300K下,具有超顺磁性,饱和磁化强度为53.7A· m2·kg-1;具有惰性端基的MPEG修饰于SPIONs表面,为其提供了良好的水分散性.采用盐桥法萃取清洗工艺可清除过量的MPEG,有利于SPIONs更好的应用在生物医学领域.     

高浓度石墨烯水分散液的制备与表征

利用高压均质液相剥离法,以鳞片石墨为原料,水为介质,制备高浓度石墨烯水分散液。采用紫外可见光谱研究表明活性剂浓度、高压均质压力和循环次数对石墨烯水分散液浓度C_G的影响。通过拉曼光谱、扫描电镜、透射电镜、激光粒度仪分析水分散液中石墨烯的结构和形貌。结果表明:通过调节各工艺参数,获得了浓度为324.3mg·L^-1的石墨烯水分散液,所得浓度是超声液相剥离法的10倍;石墨烯水分散液中石墨烯缺陷少、厚度薄、片径大,具有良好的品质;将所得石墨烯分散液制备石墨烯自支撑膜,其电导率可达3.2×10~4S·m^-1。     

纳米Si粉分散对硅碳负极性能的影响

通过高频感应等离子蒸发凝聚法制备得到的纳米Si粉结晶性好,球形度高,表面光滑,比表面积为40.03 m~2/g,平均粒径为64.05 nm。以乙二醇和去离子水为分散介质,制备了质量分数10%的纳米Si粉分散液,在乙二醇体系中纳米Si粉颗粒的分散稳定性更好,分散粒径更小,粒度分布为94.17~152.88 nm。以纳米Si粉乙二醇分散液与石墨(G)复合调浆制备的m(G):m(Si)=9:1的复合负极材料电化学性能更优,首次放电比容量为812.5 mA·h/g,可逆充电比容量可达631.0 mA·h/g,30次循环后的容量保持率为73.74%。     

液相合成超小TiO2纳米簇及其光催化性质

稳定原子团簇是高效催化剂在物质结构上的发展方向。研究将正钛酸四丁酯的水解产物在80℃下水中胶溶得到了粒径2 nm左右的超小TiO₂纳米簇。XRD和HRTEM分析结果显示: 这种超小TiO₂纳米簇为锐钛矿型晶体结构; 采用XPS测定其仅含Ti⁴⁺, 无氧空位缺陷; 采用BET测试其比表面积为269.28 m²/g; 通过紫外-可见透射光谱, 计算光学带隙为3.57 eV, 表现出小尺寸化量子效应。这种超小TiO₂纳米簇在235~340 nm波长范围有强吸收带, 使得其在太阳光照射下可将Cr⁶⁺彻底还原成Cr³⁺。在重铬酸钾溶液中紫外光照下Cr⁶⁺的光催化还原实验发现, 超小TiO₂纳米簇对Cr⁶⁺还原效率比普通TiO₂纳米晶提高了4倍以上。     

双模板-水热炭化制备马蹄形中空多孔炭及其电化学性能

以木糖为碳源,利用嵌段共聚物聚环氧乙烷-聚环氧丙烷-聚环氧乙烷(P123)/十二烷基硫酸钠(SDS)混合乳液构筑微反应器,水热炭化制备马蹄形中空多孔炭。研究表明木糖在微反应器与溶液界面发生水热反应, 160℃水热条件下P123的亲水聚环氧乙烷嵌段(PEO)亲水性下降并向乳液内部增溶,使乳液逐渐润胀和破裂。P123/SDS质量比会影响微反应器的完整度,而水热时间可以调控微反应器的开口角度和空腔直径。开放性空腔能储存更多电荷和离子并缩短传输距离,使多孔炭的比电容和能量密度增大且与空腔直径呈正相关关系。当P123/SDS质量比为1.25:1、水热时间为12h时,马蹄形中空多孔炭的开口角度(63°)和空腔直径(80nm)最大、电化学性能最佳,在6 mol·L^-1 KOH三电极体系中电流密度1 A·g^-1时比电容达292 F·g^-1;在两电极体系中电流密度0.2 A·g^-1时比电容达185 F·g^-1,能量密度达6.44 Wh·kg^-1;电流密度5 A·g^...     

ZnO/CaCO3复合材料的制备及其在丁苯橡胶硫化中的应用

采用液相沉淀法制备了ZnO/CaCO₃复合粉体,考察了工艺参数对形貌和分散状态的影响,分析了ZnO在CaCO₃表面的组装过程和ZnO的生长方式,测试了复合粉体的硫化活化性能。研究结果表明:当ZnO和CaCO₃质量比为1∶2,沉淀反应物物质的量的配比为1∶1,煅烧温度为300~350℃时,ZnO/CaCO₃复合粉体比表面积可达19.827 m²/g且有着良好的分散状态,CaCO₃表面ZnO的粒径较小(5~10 nm)。在CaCO₃表面上反应生成的羟基磷灰石对Zn²⁺的吸附的作用是将ZnO与CaCO₃成功组装在一起的关键,也是ZnO沿垂直CaCO₃表面方向生长的原因。将复合粉体应用于丁苯橡胶硫化中,硫化时转矩值最高达10.07 dN·m,硫化速率CRI最快为0.247 s^-1。     

高温多元醇法制备超顺磁CoFe2O4纳米颗粒磁共振造影剂

以FeCl₃·6H₂O、CoCl₂·6H₂O和HOOC-PEG-COOH为反应物, 利用高温多元醇法制备了核心粒径为5~10nm的超顺磁CoFe₂O₄纳米颗粒, 样品在水溶液中具有良好分散性. 通过改变修饰剂的种类和用量、反应温度及反应时间可以对纳米颗粒的尺寸、水中分散性及磁性能产生影响. 研究表明：选用带有强极性基团的修饰剂, 增加修饰剂的用量, 提高反应温度和延长反应时间, 可以增大颗粒的尺寸, 改善颗粒的分散性, 窄化粒径分布. 实验获得的最佳生长条件为：金属盐总量与修饰剂质量比为1∶10, 在210~220℃之间反应2h. 磁性能研究表明所得样品在室温下具有超顺磁性, 其饱和磁化强度与尺寸有关.     

磁流体在交变磁场中的热效应研究

制备了平均粒径分别为4、6 和8nm 的Fe3O4 粒子,将其分散在不同的介质中,在63kHz、7kA/m的交变磁场中研究其热效应。实验结果显示,粒径较大的Fe3O4 粒子具有较高的产热比功率(SAR),Fe3O4 粒子经过表面处理后SAR显著增加,而且SAR随表面活性剂不同而不同,还显示SAR与磁场强度的平方成正比。     

Monodispersed magnetite nanoparticles optimized for magnetic fluid hyperthermia: Implications in biological systems

Magnetite (Fe(3)O(4)) nanoparticles (MNPs) are suitable materials for Magnetic Fluid Hyperthermia (MFH), provided their size is carefully tailored to the applied alternating magnetic field (AMF) frequency. Since aqueous synthesis routes produce polydisperse MNPs that are not tailored for any specific AMF frequency, we have developed a comprehensive protocol for synthesizing highly monodispersed MNPs in organic solvents, specifically tailored for our field conditions (f = 376 kHz, H(0) = 13.4 kA∕m) and subsequently transferred them to water using a biocompatible amphiphilic polymer. These MNPs (σ(avg.)?=?0.175) show truly size-dependent heating rates, indicated by a sharp peak in the specific loss power (SLP, W∕g Fe(3)O(4)) for 16 nm (diameter) particles. For broader size distributions (σ(avg.)?=?0.266), we observe a 30% drop in overall SLP. Furthermore, heating measurements in biological medium [Dulbecco's modified Eagle medium (DMEM)?+?10% fetal bovine serum] show a significant drop for SLP (～30% reduction in 16 nm MNPs). Dynamic Light Scattering (DLS) measurements show particle hydrodynamic size increases over time once dispersed in DMEM, indicating particle agglomeration. Since the effective magnetic relaxation time of MNPs is determined by fractional contribution of the Neel (independent of hydrodynamic size) and Brownian (dependent on hydrodynamic size) components, we conclude that agglomeration in biological medium modifies the Brownian contribution and thus the net heating capacity of MNPs.     

Preparation of Water-Dispersible and Biocompatible Iron Oxide Nanoparticles for MRI Agent

Highly monodisperse superparamagnetic iron oxide nanoparticles (SPIONs, 7.5 nm gamma- F₂O₃) were synthesized by thermal decomposition of iron pentacarbonyl and consecutive aeration in organic medium. By treating with a small amount of iron pentacarbonyl, Fe-rich surface has been formed on SPION. Water-dispersible SPIONs (SPION-MPA) were prepared by Fe-S covalent conjugation between Fe-rich SPION and mercaptopropionic acid (MPA) and then, transformed to SPION-MPA-dextran composite by physical adsorption of biocompatible polymer dextran. The hydrodynamic diameter of SPION-MPA-dextran was in the range of 225~237 nm in water. MR contrast and spin-spin relaxation intensity of our SPION-MPA-dextran were similar to those of the commercial products, Ferridex and Resovist.     

Characterization of the biocompatible magnetic colloid on the basis of Fe3O4 nanoparticles coated with dextran, used as contrast agent in magnetic resonance imaging

The magnetic resonance imaging contrast agent, the so-called Endorem colloidal suspension on the basis of superparamagnetic iron oxide nanoparticles (mean diameter of 5.5 nm) coated with dextran, were characterized on the basis of several measurement techniques to determine the parameters of their most important physical and chemical properties. It is assumed that each nanoparticle is consisted of Fe3O4 monodomain and it was observed that its oxidation to gamma-Fe2O3 occurs at 253.1 degrees C. The M?ssbauer spectroscopy have shown a superparamagnetic behavior of the magnetic nanoparticles. The Magnetic Resonance results show an increase of the relaxation times T1, T2, and T2* with decreasing concentration of iron oxide nanoparticles. The relaxation effects of SPIONs contrast agents are influenced by their local concentration as well as the applied field strength and the environment in which these agents interact with surrounding protons. The proton relaxation rates presented a linear behavior with concentration. The measured values of thermo-optic coefficient dn/dT, thermal conductivity kappa, optical birefringence delta n0, nonlinear refractive index n2, nonlinear absorption beta' and third-order nonlinear susceptibility |chi(3)| are also reported.     

Effect of Synthesis Parameters on the Properties of Superparamagnetic Iron Oxide Nanoparticles

Iron oxide nanoparticles were coprecipitated in air medium using different sodium hydroxide (NaOH) concentrations, and their structural and magnetic properties were studied. It was observed that the precipitation of superparamagnetic iron oxide nanoparticles could be achieved above a critical NaOH concentration. This was followed by the investigation of the effect of the stirring rate on the structural and magnetic properties of the nanoparticles precipitated at 8.5?M NaOH and over. Morphological observation made by a transmission electron microscope (TEM) showed that the particle size of iron oxide nanoparticles was around 7.5?nm. Magnetization curves measured by a vibrating sample magnetometer showed zero coercivity indicating that the samples are superparamagnetic and the highest saturation magnetization (70.4?emu/g) was obtained at the stirring rate of 1100?rpm. The mean particle sizes of iron oxide nanoparticles calculated from the magnetization data are found to be consistent with the particle sizes obtained from the TEM images.     

Green synthesis of superparamagnetic magnetite nanoparticles: effect of natural surfactant and heat treatment on the magnetic properties

A facile and eco-friendly synthetic approach was employed to synthesize superparamagnetic magnetite (Fe₃O₄) nanoparticles with cubic lattice structure. Zucchini and pomegranate peel-extracts were used as natural stabilizer and surfactant. The X-ray diffraction patterns revealed that the green synthetic technique was successful in formation of highly distributed Fe₃O₄ nanoparticles using both of the above extracts. The infrared (IR) analysis further confirmed the phase formation and the binding of extracts with Fe₃O₄ nanoparticles. Based on UV–Vis analysis, the samples showed the characteristic of surface plasmon resonance in the presence of Fe₃O₄ nanoparticles. The as-synthesized samples were heated at 550 °C for 2 h. It was found that the particles however grew, their sizes remained in nanoscale regime, indicating their thermal stability. The VSM analysis indicated that the as-synthesized samples have a saturation magnetization of 21.4 emu/g (using zucchini peel extract) and 13.3 emu/g (using pomegranate peel extract), which increased respectively to 45.8 emu/g and 38.1 emu/g after the heating process. A negligible coercivity in the samples with the particle sizes of less than 10 nm suggests superparamagnetic behavior of the samples.     

The development of stable aqueous suspensions of PEGylated SPIONs for biomedical applications

We report here the development of stable aqueous suspensions of biocompatible superparamagnetic iron oxide nanoparticles (SPIONs). These so-called ferrofluids are useful in a large spectrum of modern biomedical applications, including novel diagnostic tools and targeted therapeutics. In order to provide prolonged circulation times for the nanoparticles in?vivo, the initial iron oxide nanoparticles were coated with a biocompatible polymer poly(ethylene glycol) (PEG). To permit covalent bonding of PEG to the SPION surface, the latter was functionalized with a coupling agent, 3-aminopropyltrimethoxysilane (APS). This novel method of SPION PEGylation has been reproduced in numerous independent preparations. At each preparation step, particular attention was paid to determine the physico-chemical characteristics of the samples using a number of analytical techniques such as atomic absorption, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, transmission electron microscopy (TEM), photon correlation spectroscopy (PCS, used for hydrodynamic diameter and zeta potential measurements) and magnetization measurements. The results confirm that aqueous suspensions of PEGylated SPIONs are stabilized by steric hindrance over a wide pH range between pH 4 and 10. Furthermore, the fact that the nanoparticle surface is nearly neutral is in agreement with immunological stealthiness expected for the future biomedical applications in?vivo.     

LHRH-functionalized superparamagnetic iron oxide nanoparticles for breast cancer targeting and contrast enhancement in MRI

This paper shows that superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to luteinizing hormone releasing hormone (LHRH) (LHRH–SPIONs), can be used to target breast cancer cells. They also act as contrast enhancement agents during the magnetic resonance imaging of breast cancer xenografts. A combination of transmission electron microscopy (TEM) and spectrophotometric analysis was used in our experiments, to investigate the specific accumulation of the functionalized superparamagnetic iron oxide nanoparticles (SPIONs) in cancer cells. The contrast enhancement of conventional T2 images obtained from the tumor tissue and of breast cancer xenograft bearing mice is shown to be much greater than that in saline controls, when the tissues were injected with LHRH–SPIONs. Magnetic anisotropy multi-CRAZED images of tissues extracted from mice injected with SPIONs were also found to have enhanced MRI contrast in breast cancer xenografts and metastases in the lungs.     

Synthesis and characterization of ultrafine poly(vinylalcohol phosphate) coated magnetite nanoparticles

Nanosized magnetite (Fe3O4) particles showing superparamagnetism at room temperature have been prepared by controlled coprecipitation of Fe2+ and Fe3+ in presence of highly hydrophilic poly(vinylalcohol phosphate)(PVAP). The impact of polymer concentration on particle size, size distribution, colloidal stability, and magnetic property has been extensively studied. The aqueous suspension of magnetite, prepared using 1% PVAP solution is stable for four weeks at pH 5-8. X-ray diffractograms show the formation of nanocrystalline inverse spinel phase magnetite. Transmission Electron Microscopy confirmed well dispersed cubic magnetite particles of size of about 5.8 nm. Dynamic Light Scattering measurement shows narrow distribution of hydrodynamic size of particle aggregates. Infrared spectra of samples show strong Fe--O--P bond on the oxide surface. UV-visible studies show aqueous dispersion of magnetite formed by using 1% PVAP solution is stable at least for four weeks without any detoriation of particle size. Magnetization measurements at room temperature show superparamagnetic nature of polymer coated magnetite nanoparticles.     

Synthesis of hydrophilic superparamagnetic magnetite nanoparticles via thermal decomposition of Fe(acac), in 80 vol% TREG + 20 vol% TREM

In this paper, we report single step synthesis of hydrophilic superparamagnetic magnetite nanoparticles by thermolysis of Fe(acac)3 and their characterization of the properties relevant to biomedical applications like hyperthermia and magnetic resonance imaging (MRI). Size and morphology of the particles were determined by Transmission electron microscopy (TEM) while phase purity and structure of the particles were identified by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Magnetic properties were evaluated using vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The as prepared nanoparticles were found to be superparamagnetic with the blocking temperature of 136 K and were easily suspendable in water. Cytotoxicity studies on human cervical (SiHa), mouse melanoma (B16F10) and mouse primary fibroblast cells demonstrated that up to a dose of 0.1 mg/ml, the magnetite nanoparticles were nontoxic to the cells. To evaluate the feasibility of their uses in hyperthermia and MRI applications, specific absorption rate (SAR) and spin-spin relaxation time (T2) were measured respectively. SAR has been calculated to be above 80 Watt/g for samples with the iron concentration of 5-20 mg/ml at 10 kA/m AC magnetic field and 425 kHz frequency. r2 relaxivity value was measured as 358.4 mM(-1)S(-1) which is almost double as compared to that of the Resovist, a commercially available MRI contrast agent. Thus the as-prepared magnetite nanoparticles may be used for hyperthermia and MRI applications due to their promising SAR and r2 values.