Preparation and in vitro evaluation of an ultrasound-triggered drug delivery system: 10-hydroxycamptothecin loaded PLA microbubbles

10-Hydroxycamptothecin (HCPT) loaded PLA microbubbles, used as an ultrasound-triggered drug delivery system, were fabricated by a double emulsion-solvent evaporation method. The obtained microbubbles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and confocal laser scanning microscope (CLSM). In addition, the effect of diagnostic ultrasound exposure on BEL-7402 cells combined with HCPT-loaded PLA microbubbles was evaluated using cytotoxicity assay, CLSM and flow cytometry (FCM). It was found that the HCPT-loaded PLA microbubbles showed smooth surface and spherical shape, and the drug was amorphously dispersed within the shell and the drug loading content reached up to 1.69%. Nearly 20% of HCPT was released upon exposure to diagnostic ultrasound at frequency of 3.5 MHz for 10 min. Moreover, HCPT fluorescence in the cells treated only with the HCPT-loaded PLA microbubbles was discernible, but less intense, while those treated with the microbubbles in conjunction with ultrasound exposure was evident and intense, indicating an increased cellular uptake of HCPT by ultrasound exposure. Cytotoxicity test on BEL-7402 cells indicated that the HCPT-loaded PLA microbubbles combined with ultrasound exposure were more cytotoxic than the microbubbles alone. The results suggest that the combination of drug loaded PLA microbubbles and diagnostic ultrasound exposure exhibit an effective intracellular drug uptake by tumor cells, indicating their great potential for antitumor therapy.     

A Multifunctional Magnetic Composite Material as a Drug Delivery System and a Magnetic Resonance Contrast Agent

Magnetic iron oxide coated in hydrogenation silica (Fe₃O₄@HSiO₂) is constructed as both a tumor drug carrier and a magnetic resonance (MR) contrast agent. Colchicine (COLC) is loaded in Fe₃O₄@HSiO₂ with the highest amount of 28.3 wt% at pH 9. The release performance of COLC can be controlled by pH, as the porous HSiO₂ shell can partially shed at pH below 3.0 to facilitate the release of COLC. MR imaging (MRI) tests prove that Fe₃O₄@HSiO₂ at pH 3.0 (H⁺‐Fe₃O₄@HSiO₂) shows a stronger MR contrast enhancement than Fe₃O₄. Cytotoxicity experiment indicates that Fe₃O₄@HSiO₂ has excellent biocompatibility and magnetic targeting performance. Additionally, COLC‐loaded Fe₃O₄@HSiO₂ (Fe₃O₄@HSiO₂–COLC) displays a higher inhibition effect on tumor cells under a magnetic field than free COLC. The visibility upon MRI, high targeting, and pH‐controlled release characteristics of Fe₃O₄@HSiO₂–COLC are favorable to achieve the aim of reducing side effects to normal tissues, making Fe₃O₄@HSiO₂–COLC an attractive drug delivery system for nanomedicine.     

The thermal and thermomechanical behaviors of Spartium junceum flour reinforced polypropylene composites: effects of treatment and flour content

The effects of Spartium junceum (SJ) flour content, treatment time on the thermal and thermomechanical properties of polypropylene/Spartium junceum flour (PP/SJ) composites were studied. In order to improve the interfacial adhesion between the PP matrix and the SJ flour, SJ flour was treated with NaOH (2 wt%) for 8, 24 and 48 h at ambient temperature, respectively, and treated by vinyltrimethoxysilane (VTMS) (5 wt%). The results of thermogravimetric analysis (TGA) of SJ flour shows that the treatment improves the thermal stability of SJ flour. DSC analysis measurements illustrates that the addition of SJ flour increase the degree of crystallinity X_c, which indicate that the SJ flour plays a significant role in heterogeneous nucleating of PP matrix. The chemical treatments significantly affect the storage modulus of composite, where E′ increases for composites with treated flour in comparison to the untreated ones.     

腐败的三方动态博弈模型及其治理对策

本建立了腐败问题的三方动态博弈模型，并求出博弈模型的均衡解模型，根据均衡解，提出了治理腐败问题的对策。     

基于多Agent的车间任务招投标粗模糊集建模研究

首先通过相识集、招标集、投标集和任务集的概念 ,描述制造执行系统中的调度 Agent与资源 A-gent间任务招投标过程模型 ;基于任务的属性和资源 Agent完成任务的成本、质量、负荷和时间等属性 ,定义论域上的模糊集 ,将模糊集中的隶属度函数作为粗集的属性 ,在模糊集上作截集 ,从而获得系统的分类知识 ;收集样本数据 ,构造并分析决策表 ,进而获得调度 Agent调度决策知识 ;应用调度知识进行推理 ,从争取获得招标任务的若干个资源 Agent中 ,选出最适合招标任务的中标者 .     

粉煤灰地聚合物材料的合成

以粉煤灰为主要原料,以沸石或膨润土为矿物掺合料,NaOH和生石灰粉为激发剂,在常温下合成粉煤灰地聚合物材料。正交试验表明,沸石或膨润土能促进粉煤灰地聚合物合成,用NaOH和生石灰粉作为复合激发剂,可合成28d抗压、抗折强度分别大于26MPa、8MPa的粉煤灰地聚合物材料。红外光谱和扫描电镜分析表明,当采用沸石为矿物掺合料时,粉煤灰地聚合物材料中非晶态铝硅酸盐量最多,且结构中存在许多连续的三维网状PSDS型地聚合物产物。并且,以沸石为掺合料的粉煤灰地聚合物材料具有很好的强度和耐久性。     

一种含马来酰亚胺环氧树脂固化剂的合成与结构、光谱和热力学性质研究

以马来酸酐、对硝基苯胺、环氧氯丙烷为原料,首先合成出N-(4-硝基苯基)马来酰亚胺(NPMI)、再将其催化还原成N-(4-氨基苯基)马来酰亚胺(APMI),最后以APMI与环氧氯丙烷反应合成出一种新型的含马来酰亚胺环氧树脂固化剂N-(4-氨基苯基马来酰亚胺)二缩水甘油胺(MPDGA).采用密度泛函理论B3LYP/6-311++G(d,p)方法,研究了所合成的MPDGA分子的几何结构、电子结构及热力学性质.获得了它们的红外光谱、电子光谱和分子轨道图,以及标准摩尔热容C_(pm)~θ、标准摩尔熵S_m~θ、标准摩尔焓H_m~θ等气态热力学性质与温度的变化关系,同时获得了MPDGA分子的标准摩尔生成焓Δ_fH_m~θ和标准摩尔生成自由能ΔfGθm数据.     

Two-dimensional differential adherence of neuroblasts in laser micromachined CAD/CAM agarose channels

Laser micromachining of hydrophobic gels into CAD/CAM patterns was used to develop differentially adherent surfaces and induce the attachment of B35 rat neuroblasts that would later form engineered nerve bundles. Narrow channels, 60-400 μm wide, were micromachined in a 2% agarose gel using an ArF laser, and subsequently filled with an extracellular matrix gel. Upon the addition of 1 ml of a 2 × 104 cells/ml neuroblast suspension, the cells selectively adhered to the ECM-lined channels in a non-confluent manner and we monitored their growth at various time points. The adherent neuroblasts were fluorescently imaged with a propidium iodide live/dead assay, which revealed that the cells were alive within the channels. After 72 h growth, the neuroblasts grew, proliferated, and differentiated into nerve bundles. The fully grown 1 cm long nerve bundle organoids maintained an aspect ratio on the order of 100. The results presented in this paper provide the foundation for laser micromachining technique to develop bioactive substrates for development of three-dimensional tissues. Laser micromachining offers rapid prototyping of substrates, excellent resolution, control of pattern depth and dimensions, and ease of fabrication.     

Tensile properties of styrene-butadiene rubber/silica composites with mercapto functional silane coupling agents: influences of loading method and alkoxy group number

The influences of alkoxy group number and loading method of silane coupling agents on the mechanical properties of a styrene-butadiene rubber/silica composite were investigated. Mercapto functional silane coupling agents with dialkoxy and trialkoxy structures were used. The pre-treatment method and the integral blend method were compared. Both the fracture stress and modulus at 200% strain were higher in the pre-treatment than in the integral blend for dialkoxy type composites. However, they were higher in the integral blend than in the pre-treatment for trialkoxy-type composites. The interaction between the silane chains on the silica surface and the rubber molecular chains at the interfacial region was estimated by ¹H pulse nuclear magnetic resonance spectroscopy using an unvulcanized silica/rubber mixture. It was found that the binding of rubber molecular chains by the silane chains was higher in the pre-treatment system for dialkoxy-type composites, whereas it was higher in the integral blend for trialkoxy-type composites. The reason is proposed as follows: in the pre-treatment for dialkoxy type, a linear silane chain formed in the case of multi-layer coverage. The silane chain entangled with the rubber chain in the interfacial region and improved the reinforcement effect. For the trialkoxy type, a network structure formed using the pre-treatment method, lowering the amount of entanglement. However, in the integral blend for trialkoxy type, the formation of the silane network and the entanglement progressed simultaneously during the preparation process. A well-entangled interfacial region was formed.     

Effect of Trader Composition on Stock Market

In this study, we build a double auction market model, which containstwo types of agent traders, i.e., the noise traders and fundamentalists, to investigate the effect of the trader composition on the stock market. It is found that, the non-trivial Hurst exponent and the fat-tailed distribution of transaction prices can be observed at any ratio of the noise traders. Analyses on the price variation properties, including the Hurst exponent and the price variation region, show that these properties are stable when the ratio is moderate. However, the non-price variation properties, including the trading volume and the profitability of the two kinds of agents, do not keep stable untrivially in any interval of the ratio of noise traders.