新型悬浮聚合法制备多孔磁性高分子微球的研究

采用新型悬浮聚合法制备了平均粒径为4.06 μm的多孔磁性高分子微球.以硅烷偶联剂KH-570对羰基铁粉颗粒进行表面修饰,并经一步聚合得到多孔磁性高分子微球.SEM结果表明该微球表面由纳米级聚合物粒子层层粘合而成,粒子间孔径在几十到几百纳米之间不等.采用红外光谱及X射线衍射表征了多孔磁性高分子微球的化学成分和晶体结构.用热失重方法测得多孔磁性高分子微球中磁性物质的含量可达26.7%.     

纳米Fe3O4颗粒的表面包覆及其在磁性氧化铝载体制备中的应用

通过对共沉淀得到的Fe3O4磁性纳米颗粒在硅酸钠溶液中进行酸化处理，获得了表面包覆SiO2层的Fe3O4磁性组份. 由于SiO2的位阻作用，限制了Fe3O4微晶的团聚与继续生长，使Fe3O4核心分散在产物中保持较小的晶粒尺寸，包覆产物表现出超顺磁性，同时提高了磁性组份的耐候性. 将上述磁性组份加入到氢氧化铝溶胶中，采用内凝胶法(油中成型法)制备出磁性球形氧化铝载体，磁性组份外表的SiO2包覆层的隔离作用防止了磁性核心与载体组份之间发生的反应，也避免了铁组份可能对后续负载的催化剂活性组份造成的不良影响. 制备的磁性氧化铝载体具备超顺磁性，磁性氧化铝载体的磁性能因内部磁性核心组份的改变而发生一定变化.     

甲基丙烯酸β-羟乙酯共聚水凝胶的合成及性能研究

以HEMA、AAM为共聚单体,采用溶液聚合法合成了HEMA/AAM共聚水凝胶,并对其溶胀动力学、离子强度、温度、pH值等性能进行了测定。实验表明:合成的水凝胶初始溶胀迅速,达到平衡溶胀比平衡约6h;在不同离子强度的水溶液中,随着离子强度I的增大,凝胶的ESR不断降低;在pH<7时,其EKR随pH值的增加而减少,在pH>7时,其ESR随pH值的增加而猛增,因为发生了水解反应;凝胶的ESR随温度的升高而降低。     

不同形貌纳米Fe3O4粒子磁流体的稳定性及其流度学性能

选用无规则、正八面体和六方片状形貌的纳米Fe3O4磁性颗粒作为磁流体固相材料,通过设计组装基于L–C振荡电路的磁流体稳定性测试仪,确定制备稳定磁流体的较佳表面改性活性剂和辅助表面活性剂用量。同时,对含有不同形貌磁性颗粒的磁流体在水平方向磁场以及竖直方向磁场中的磁流变学性能进行了研究。结果表明：在外加水平方向180、350、500Gs磁感应强度,磁流体的黏度、剪切应力基本不变,磁流体表现出Newtonian流体的流变学特性;在外加竖直方向360、740、1130Gs磁感应强度,磁流体表现出Bingham流体的流变学特性;对于含有正八面体形貌纳米Fe3O4颗粒的磁流体,其黏度和剪切应力随外加磁场的变化较大。     

Head-to-Head Comparison of Selected Extra- and Intracellular CO-Releasing Molecules on Their CO-Releasing and Anti-Inflammatory Properties

Over the past decade, a variety of carbon monoxide releasing molecules (CORMs) have been developed and tested. Some CORMs spontaneously release CO once in solution, while others require a trigger mechanism to release the bound CO from its molecular complex. The modulation of biological systems by CORMs depends largely on the spatiotemporal release of CO, which likely differs among the different types of CORMs. In spontaneously releasing CORMs, CO is released extracellularly and crosses the cell membrane to interact with intracellular targets. Other CORMs can directly release CO intracellularly, which may be a more efficient method to modulate biological systems. In the present study, we compared the efficacy of extracellular and intracellular CO-releasing CORMs that either release CO spontaneously or require an enzymatic trigger. The efficacy of such CORMs to modulate HO-1 and VCAM-1 expression in TNF-α-stimulated human umbilical vein endothelial cells (HUVEC) was evaluated.     

盐度对N-异丙基丙烯酰胺与丙烯酰胺共聚物性能的影响

采用自由基共聚的方法,合成了温度敏感水凝胶。在不同环境温度测试了N-异丙基丙烯酰胺与丙烯酰胺共聚物的拉伸性能,并且在不同盐度下研究了共聚物的机械性能,试验中发现溶胀与未溶胀的水凝胶在力学性能上的差异。本文还研究了盐度对LCST(最低临界温度)的影响,试验结果表明,改变溶液盐度是一种有效控制水凝胶LCST的方法。     

AM与HEMA共聚制备水凝胶接触镜材料及其溶胀性能

采用丙烯酰胺(AM)与甲基丙烯酸β-羟乙酯(HEMA)进行本体共聚制备水凝胶接触镜材料,研究了水凝胶的溶胀性能及其温度和pH值敏感性。结果表明,引发剂过氧化苯甲酰(BPO)用量为反应单体总质量的0.3%、反应温度80℃,产物溶胀之后为无色透明的玻璃状水凝胶;共聚物水凝胶具有较好的pH值敏感性,水凝胶在酸性溶液中溶胀,在碱性溶液中收缩:含有AM的水凝胶,其pH值敏感性较大:随AM的含量增大,共聚物水凝胶的溶胀速度和饱和含水量增大,随温度升高,水凝胶的饱和含水量下降,共聚物水凝胶中AM的含量对其温度敏感性无显著影响:SEM照片显示,AM与HEMA共聚物存在均匀的纤维状结构,并且共聚物中AM的含量越大,这种纤维状结构越大、越明显。     

均匀超细Fe3O4磁流体的研究

实验研究了均匀超细Fe3O4磁流体的制备工艺，对所制得的系列磁流体进行了性能检测和结构表征。所得磁流体具有良好的稳定性和磁性能，根据电子衍射图计算了粒子的晶格常数，证明磁流体中的物质组成为Fe3O4，透射电镜(TEM)表明Fe3O4粒子细小而均匀，一般为6～8nm，具有良好的可重复性，为工业放大和产业化应用奠定了基础。     

Fe_3O_4@rGO复合磁性粒子对聚氨酯弹性体复合材料性能的影响

将3种不同的Fe3O4@还原氧化石墨烯(rGO)–四氢呋喃(THF)复合磁性粒子分散液分别与聚氨酯(PUR)弹性体进行原位聚合制备3种PUR弹性体/Fe3O4@rGO磁性复合材料,并对其组分和分散状态进行了表征,系统研究了Fe3O4@rGO复合磁性粒子对PUR弹性体磁性能、热性能和力学性能的影响。结果表明,仅掺入质量分数为0.5%的Fe3O4@rGO复合磁性粒子可以显著提高PUR弹性体的性能。随着Fe3O4@rGO复合磁性粒子中rGO含量的增加,PUR弹性体复合材料的饱和磁化强度逐渐下降,热稳定性和力学性能均逐渐提高。当复合磁性粒子中rGO质量分数为60%时,复合材料的力学性能最佳,拉伸强度、断裂伸长率和拉伸弹性模量分别为35.31MPa,438.90%和86.42MPa,玻璃化转变温度、最大损耗因子和在–60℃时的储能模量分别达10.64℃,0.41和3805.84MPa。此外,扫描电子显微镜观察发现,Fe3O4@rGO复合磁性粒子在基体中具有良好的分散性。     

Preparation of Graphene-Based Hydrogel Thermal Interface Materials with Excellent Heat Dissipation and Mechanical Properties

Heat dissipation has become an essential factor affecting the performance and operating life of electronic devices as the development of modern electronic devices continues to miniaturize and integrate to increase power density. The development of new thermal interface materials has been the key solution to heat dissipation. Herein, a high thermal conductive graphene-based hydrogel (G/PVP-PVA) with an interpenetrating network is successfully constructed by physical cross-linking combined with the freeze–thaw process. The effect of the preparation parameters on its all-around performance is evaluated in detail. When the graphene dosage is 0.33%, the maximal tensile stress of the hydrogel is 322.4 kPa, the self-recovery is 95.4%, and the thermal conductivity is as high as 1.486 W m⁻¹ K⁻¹. The cooling simulation experiment shows that the hydrogel can adhere closely to the wall to reduce the air thermal resistance effectively, and the cooling rate is as high as 5.04 °C min⁻¹. The simulation experiment of the human body cooling shows that its cooling rate is 1.10 °C min⁻¹, while that for a commercial hydrogel is 0.27 °C min⁻¹. The G/PVP-PVA can give a practically potential solution for the thermal management of flexible electronic products and provides a new material for an efficient medical cooling application.     

Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network.     

表面含羧基的磁性高分子微球的制备和表征

以共沉淀法制备的Fe3O4为磁性来源,选用丙烯酰胺、N,N′-亚甲基双(丙烯酰胺)和丙烯酸分别作为聚合单体、交联剂和功能基单体,通过反相乳液聚合,包裹制备携带羧基的磁性高分子微球。考察了Fe3O4投入量、功能基单体量、交联剂量、聚合时间和介质的变化对磁性高分子微球的形态、磁性质及表面羧基含量的影响。采用SEMI、R、721E分光光度计和化学滴定法进行表征,制备出粒径在500 nm~10μm,表面羧基携带量为1.0 mmol/g的磁性高分子微球。     

Fe3O4水基磁流体的制备及其分散性能研究

采用共沉淀法制备了纯Fe3O4纳米粒子,分别用高氯酸、四甲基羟胺和油酸/十二烷基苯磺酸钠为表面活性剂对其进行表面处理后分散在水中,得到了3种水基磁流体,对这3种磁流体的浓度及稳定性进行了测定。实验结果显示:酸性、碱性和中性水基磁流体中Fe3O4的浓度分别为4.8%、5.8%和8.1%,其中中性水基磁流体中粒子的分散性能最佳;经过离心后,3种水基磁流体中的粒子均产生了沉降,且酸性和碱性磁流体中的粒子比中性磁流体中的粒子沉降的多。在此基础上,对影响粒子分散稳定性的机理进行了初步探讨。     

Different Storage Conditions Influence Biocompatibility and Physicochemical Properties of Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted increasing attention in many biomedical fields. In magnetic drug targeting SPIONs are injected into a tumour supplying artery and accumulated inside the tumour with a magnet. The effectiveness of this therapy is thus dependent on magnetic properties, stability and biocompatibility of the particles. A good knowledge of the effect of storage conditions on those parameters is of utmost importance for the translation of the therapy concept into the clinic and for reproducibility in preclinical studies. Here, core shell SPIONs with a hybrid coating consisting of lauric acid and albumin were stored at different temperatures from 4 to 45 °C over twelve weeks and periodically tested for their physicochemical properties over time. Surprisingly, even at the highest storage temperature we did not observe denaturation of the protein or colloidal instability. However, the saturation magnetisation decreased by maximally 28.8% with clear correlation to time and storage temperature. Furthermore, the biocompatibility was clearly affected, as cellular uptake of the SPIONs into human T-lymphoma cells was crucially dependent on the storage conditions. Taken together, the results show that the particle properties undergo significant changes over time depending on the way they are stored.     

Preparation and Swelling Study of a pH-Dependent Interpolymeric Hydrogel Based on Chitosan for Controlled Drug Release

Novel pH-dependent, biodegradable interpolymeric network (IPN) hydrogels were prepared for controlled drug release investigations. The IPN hydrogels were prepared by irradiation of solutions of N-acryloyglycine (NAGly), polyethylene glycol diacrylate (PEGDA) mixed with chitosan, in the presence of a lower amount of glutaraldehyde as the crosslinker and using 2,2-dimethoxy-2-phenyl acetophenone as the photo-initiator. The equilibrium swelling studies were carried out for the gels at 37°C in buffer solutions of pH 2.1 and 7.4 (simulated gastric and intestinal fluids, respectively). 5-Fluorouracil (5-FU) was entrapped, as a model therapeutic agent, in the hydrogels and equilibrium-swelling studies were carried out for the drug-entrapped gels at 37°C. The in-vitro release profiles of the drug were established at 37°C in pH 2.1 and 7.4.     

A Study on the Effect of Butyl Methacrylate Content on Swelling and Controlled-Release Behavior of Poly (Acrylamide-co-Butyl-Methacrylate-co-Acrylic Acid) Environment-Responsive Hydrogels

Poly (acrylamide-co-butyl methacrylate-co-acrylic acid) [poly (AAm-co-BMA-co-AAc)]-based environment-sensitive hydrogels were prepared by varying the butyl methacrylate (BMA) content, in the range of 20 to 66% (wt. of the total monomer) in the hydrogel. The effect of BMA content on the swelling behavior of the hydrogels was studied by keeping the other two monomers' content constant at different pH and temperatures. The synthesized hydrogels were characterized by various techniques, and release kinetics was analyzed. The application and effect of the BMA content of these hydrogels in controlled drug release of acetaminophen and model drugs were investigated.     

Effect of Kappa-Carrageenan on the Properties of Poly (Vinyl Pyrrolidone) Hydrogel Prepared by the Application of Radiation

Poly (vinyl pyrrolidone) hydrogels with kappa-carrageenan (KC) were synthesized by γ-ray irradiation. The conditions of synthesis such as variation of total radiation doses and concentration of KC were determined. The properties of the prepared hydrogels, such as gel strength, gel fraction, swelling ratio, and water absorption were evaluated. Gel strength and gel fraction attain maximum up to a certain dose but swelling ratio and water absorption decrease with increased total doses. Gel strength, swelling ratio, and water absorption increase with an increase in the concentration of KC but the gel fraction reduces.     

纳米阵列膜磁性质的蒙特卡罗模拟

计算机的模型数字模拟是进行新一代超高密度磁记录材料的研究和开发的重要手段。本文介绍了利用蒙特卡罗方法研究纳米阵列膜的磁性质的基本思想、目前取得的主要结果、面临的问题和可能的解决办法。     

Biological Properties of Iron Oxide Nanoparticles for Cellular and Molecular Magnetic Resonance Imaging

Superparamagnetic iron-oxide particles (SPIO) are used in different ways as contrast agents for magnetic resonance imaging (MRI): Particles with high nonspecific uptake are required for unspecific labeling of phagocytic cells whereas those that target specific molecules need to have very low unspecific cellular uptake. We compared iron-oxide particles with different core materials (magnetite, maghemite), different coatings (none, dextran, carboxydextran, polystyrene) and different hydrodynamic diameters (20–850 nm) for internalization kinetics, release of internalized particles, toxicity, localization of particles and ability to generate contrast in MRI. Particle uptake was investigated with U118 glioma cells und human umbilical vein endothelial cells (HUVEC), which exhibit different phagocytic properties. In both cell types, the contrast agents Resovist, B102, non-coated Fe₃O₄ particles and microspheres were better internalized than dextran-coated Nanomag particles. SPIO uptake into the cells increased with particle/iron concentrations. Maximum intracellular accumulation of iron particles was observed between 24 h to 36 h of exposure. Most particles were retained in the cells for at least two weeks, were deeply internalized, and only few remained adsorbed at the cell surface. Internalized particles clustered in the cytosol of the cells. Furthermore, all particles showed a low toxicity. By MRI, monolayers consisting of 5000 Resovist-labeled cells could easily be visualized. Thus, for unspecific cell labeling, Resovist and microspheres show the highest potential, whereas Nanomag particles are promising contrast agents for target-specific labeling.     

磁性纤维及其纱线的基本性能

通过对磁性纤维的微观形态结构、单丝力学性能及其混纺纱的断裂强力、回潮率和含水率、耐热性和耐酸碱性等性能的测试发现:磁性纤维表面分布着不规则的磁粉微粒;磁性纤维的断裂伸长率较大;磁性纤维湿纺纱的单纱断裂强力接近300 cN,其延伸性较好,回潮率和含水率均较低,耐干热性良好,耐湿热性较差,耐酸不耐碱,尤其不耐强碱。