Behavior of Endothelial Cells Regulated by a Dynamically Changed Microenvironment of Biodegradable PLLA‐PC

The influence of PLLA‐PC membranes on the behavior of vascular ECs is studied. It was found that the membranes were not cytotoxic. The cell adhesion and spread on PLLA‐PC 30/1 were initially depressed. After 1 d, however, cells attached and spread on the copolymer, and proliferated beyond 2 d. To elucidate the mechanism of this behavior, the surface morphology and the degradation products of the PLLA/PC 30/1 membrane during the culture period were tested, and Fg adsorption to the membranes was examined. It is concluded that the behavior of ECs can be regulated by a dynamically changed microenvironment of the PLLA‐PC membrane. PLLA‐PC copolymers might therefore serve as a novel material for tissue engineering.

     

新型羧甲基壳聚糖水凝胶流变性能,药物释放及细胞相容性研究

羧甲基壳聚糖含有丰富的羧基和氨基, 通过1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)共催化交联羧甲基壳聚糖形成新型水凝胶. 调节EDC/NHS用量, 制备不同交联度的羧甲基壳聚糖水凝胶(CMCS hydrogels). 研究水凝胶的流变行为, 结果表明, 高交联度的水凝胶具有较好的弹性形变能力, 较高的储存模量, 这是因为随着交联度的升高, 羧甲基壳聚糖水凝胶化学交联网络结构趋于完善. 以胸腺五肽(TP-5)为模型药物, 初步评价CMCS水凝胶药物释放行为, 结果表明水凝胶交联度越高, 胸腺五肽释放速度越慢. MTT法初步评价了水凝胶细胞毒性, 细胞形态和细胞相对增值速率, 结果表明水凝胶毒性很低. 由此可见, 水凝胶具有良好的生物相容性, 在药物缓释和组织工程领域具有广阔的应用前景.     

Spectroscopic response of ferrocene derivatives bearing a BODIPY moiety to water: a new dissociation reaction

Ferrocence and its derivatives have long been known to be a class of stable organometallic compounds, and their dissociation usually occurs under harsh conditions. Here we report a new type of ferrocene derivatives, 4,4-difluoro-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene and 4,4-difluoro-2,6-diethyl-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene, which surprisingly can hydrolyze under mild conditions. These two derivatives, initially developed as donor-acceptor probes for reactive oxygen species by incorporating the electron donor of ferrocene as a quencher into the fluorophore of BODIPY (boron dipyrromethene difluoride), barely emit fluorescence. Upon reaction with H(2)O under the irradiation of natural light at room temperature, however, both of the probes display a dramatic color change and fluorescence retrievement. Detailed experimental results reveal that the reaction of the probes with H(2)O leads to the removal of a cyclopentadiene unit and iron(II), yielding a BODIPY derivative that retains the other cyclopentadiene unit and shows a large fluorescence enhancement (over 100-fold). Moreover, the increase in fluorescence intensity is directly proportional to microamount of water, and the presence of both light and H(2)O is indispensable in the reaction, which makes the present system of great potential not only for determining water but also for forming a AND logic gate. Most importantly, the present mild dissociation reaction may give a new insight into the stability of ferrocene and its derivatives.     

天然有机化合物的质谱研究(Ⅶ)——直链邻二醇类化合物构型的确定

用硼酸三甲酯作反应试剂,以反应质谱法研究某些直链邻二醇类化合物的构型。实验结果表明:凡苏式构型的样品与硼酸三甲酯反应产生的特征离子丰度比均大于赤式构型的样品与其反应所产生的特征离子丰度比。由此可方便地利用反应质谱法来鉴别该类化合物的苏、赤式构型。     

葡萄糖激酶M197V突变的活化机理研究

葡萄糖激酶(glucokinase, GK)催化葡萄糖转变为6-磷酸葡萄糖, 是糖代谢的第一步, 所以GK活性异常在糖代谢紊乱的发生发展中起着重要作用. 对青年型早发糖尿病(maturity-onset diabetes of the young 2, MODY 2)型和高胰岛素性低血糖症(persistent hyperinsulinemic hypoglycemia of infancy, PHHI)型的深入研究证实了GK活性改变与糖尿病的发生有关. 为了研究GK活性改变的机理, 通过分子动力学模拟和隐性溶剂的自由能的计算对GK的单点突变M197V (Met¹⁹⁷ →Val)进行了理论研究. 通过GK的C^α原子均方根浮动变化(Root mean square fluctuation, RMSF)和动态相关性矩阵(Dynamic cross-correlation matrices, DCCM)分析, 显示M197V突变导致GK在活化状态的构象更加稳定. 通过包结自由能分析, 表明M197V突变可以增加GK对葡萄糖的包结亲合性, 并且理论预测突变前后的相对包结自由能差值和已有的实验结果非常吻合. 研究结果很好地从原子水平解释了GK的M197V突变的活化机理.     

Synthesis of amino-group functionalized superparamagnetic iron oxide nanoparticles and applications as biomedical labeling probes

Superparamagnetic iron oxide (SPIO) nanoparticles were synthesized by coprecipitation technique and further functionalized with amino-group to obtain amino-group functionalized (amino-SPIO) nanoparticles. The X-ray diffraction results reveal the structure of amino-SPIO nanoparticles, from which the average iron core diameter is approximately 10 nm by calculation; while Zetasizer reveals their hydrodynamic diameter are mainly distributed in the range of 40?C60 nm. These nanoparticles can be taken up by liver tissue, resulting in dramatically darkening of liver tissue under T2-magnetic resonance imaging (MRI). The spin?Cspin relaxivity coefficient of these nanoparticles is 179.20 mM^?1 s^?1 in a 1.5 T magnetic resonance system. In addition, amino-SPIO nanoparticles were conjugated to Tat (FITC) peptide and incubated with neural stem cells in vitro, the authors can detect the positive-labeling (labeled) neural stem cells showing green fluorescence, which indicates Tat (FITC) peptide-derivated amino-SPIO nanoparticles are able to enter cells. Furthermore, it was also find significant negative T2 contrast enhancement when compared with the non-nanoparticles-labeled neural stem cells in T2-weighted MRI. The amino-SPIO nanoparticles show promising potential as a new type of labeling probes, which can be used in magnetic resonance-enhanced imaging and fluorescence diagnosis.     

激光等离子体尾波加速器的发展和展望

超强激光在气体等离子体中传输时可以激发出大振幅的电子等离子体尾波。激光等离子体尾波加速器是利用该尾波对带电粒子（特别是电子和正电子）进行加速的一种新型装置。由于其加速梯度相较于现有的常规加速器可以提升1000倍,为建造超紧凑型的加速器和辐射源奠定了基础,也为将来建造基于等离子体的超高能正负电子对撞机和自由电子激光装置提供了可能。对该新型加速器的原理、特点、发展历程,尤其是近十年来的主要进展和未来发展趋势及面临的主要挑战进行简要梳理和介绍。     

N-(β-胺基-4-氯桂皮酰基)另丁胺类化合物的NMR及构型研究

本文报道了一类新化合物N-(β-胺基-4-氯桂皮酰基)另丁胺的NMR及烯胺结构中氮上质子与相邻碳上质子间的偶合。依据¹H NMR指定了这类化合物的构型,提出了一个化合物的X光衍射结果,证实了所指定的构型,用去偶技术确认了烯胺结构中氮上质子与相邻碳上质子间的偶合现象。     

Degradation of copolymers obtained by ring-opening polymerization of glycolide and -caprolactone: A high resolution NMR and ESI-MS study

Electrospray ionization-mass spectrometry (ESI-MS) and proton nuclear magnetic resonance (¹H NMR) have been used to investigate the hydrolytic degradation of copolymers obtained by bulk ring-opening copolymerization of glycolide and -caprolactone with monomer ratios ranging from 70/30 to 30/70. NMR allows changes of the average sequence distribution and composition of the components to be followed. In contrast, ESI-MS is able to reveal the detailed chemical structures of various sequences despite the molecular weight limit of 2000 Da. Combination of ESI-MS with NMR can thus provide information to describe microstructure changes during degradation. The distribution of various oligomers shown in the form of planar projections is of great interest for the design of biodegradable system aimed at medical applications.     

苯丙烯酸衍生物的热力学特性研究

激光染料分子——香豆素系列化合物【‘－‘1，8一经甲基香豆素衍生物【‘，’1的相变温度和相变偿分别与其母体7一位、6一位取代基团特性有着相互依赖关系．本文采用DSC法研究了2、3和4一甲氧基苯丙烯酸及个经基一3一甲氧基苯丙烯酸防们分别简称为1、D、m和w）在升温过程中的相变热力学特性，并对它们的结构与其热力学参数之间的关系进行了简要地分析．苯丙烯酸1、H、m和w的结构上。下：1实验部分1．1试样来源合成得到的试样，经鉴定其结构与分子式相符，并经元素分析测定，测定值与理论值相一致，表明试样具有较高纯度．1．2实验方法P…