Polymerization of lactams. 99 Preparation of polyesteramides by the anionic copolymerization of ε-caprolactam and ε-caprolactone

Polyesteramides derived from the cyclic monomers ε-caprolactam and ε-caprolactone have been synthesized by the anionic polymerization and characterized. ε-Caprolactam magnesium bromide was employed as unique initiator giving high yield of copolymer across the whole range of monomer concentrations at 150 °C. Owing to a variation of the content of ester and amide component in polyesteramide backbone a large variety of materials having diverse physico-chemical and mechanical properties have been prepared. Materials prepared were examined for mechanical characteristic. Thermal properties were characterized using DSC, temperature modulated DSC, Hi-Res^TM TGA and DMA. Viscosity measurements were employed for molecular characterization.     

Anionic polymerization of ϵ-caprolactam—LX. Ionization and solvation changes in the initial stage of the anionic polymerization of lactams in tetrahydrofuran

Interactions between potassium salts of lactams and N-acyllactam propagation centres in the initial stage of the anionic polymerization of lactams were studied by measuring changes in the electric conductivity and in the i.r. spectrum in the range of carbonyl vibration bands of these compounds and of the corresponding derivatives of open-chain alkylamides in tetrahydrofuran. The gradual rise in conductivity and u.v. absorption around 300 nm observed with these systems can be attributed to the formation of 3-oxoimide and 3-oxoamide structures by the condensation of imides.     

pePC-SAFT: Modeling of polyelectrolyte systems: 1. Vapor–liquid equilibria

A molecular thermodynamic model for polyelectrolyte systems—called pePC-SAFT—is proposed. The effect of charged monomers within the polyelectrolyte chain is explicitly taken into account in the reference term by replacing the hard-chain contribution of the PC-SAFT model by a charged-hard-chain contribution. Moreover, counterion condensation is accounted for to determine the effective number of charges along the polyion as well as of free counterions. The electrostatic contribution of the free counterions is described by a Debye–Hückel term.     

(l)- or (d)-Valine tert-butylamide grafted on permethylated β-cyclodextrin derivatives as new mixed binary chiral selectors: Versatile tools for capillary gas chromatographic enantioseparation

This work deals with the synthesis of two mixed binary chiral selectors prepared by grafting (l)- or (d)-valine tert-butylamide on permethylated cyclodextrin macrocycle. The enantioselective properties of the new chiral selectors diluted in OV11 polysiloxane (35% phenyl- and 65% methylsiloxane) were investigated by means of injections of 117 racemic mixtures. The mixed chiral selectors with (l)-valine and, to a lesser extent with (d)-valine, were found to have an improved enantioselectivity toward amino acid derivatives by comparison to permethylated cyclodextrin. The enantioseparation capability of these new chiral selectors has proven to be slightly less efficient than Chirasil-l-Val (Alltech) for amino acid derivatives, but it has been extended to include terpenes, lactones, esters, aliphatic compounds and aryl alcohols.     

卡那霉素A酶联适配体检测方法研究

通过EDC法偶联辣根过氧化物酶(HRP)和卡那霉素A(Kanamycin,KaA)分子制备酶标记物,采用棋盘滴定法确定链霉亲和素(Streptavidin,SA)的包被浓度为8 mg/L,通过单因素实验优化了检测条件,建立了卡那霉素A酶联适配体检测(Enzyme-linked aptamer assay,ELAA)方法。本方法半抑制浓度(IC50)为2.2"g/L,检出限(LOD)为0.04"g/L,检测范围(IC20～IC80)为0.07～71.5"g/L,与结构类似物无明显交叉反应;对牛奶、猪肉、猪肝、鸡肉、蜂蜜样品加标回收率在78%～100%之间,平均相对标准偏差小于11.1%。本方法特异性强、灵敏度高,适用于食品中卡那霉素A的快速检测。     

DFT study of the ring opening polymerization of ε-caprolactone by grafted lanthanide complexes: 1--Effect of the grafting mode on the reactivity of borohydride complexes

The influence of the grafting mode of a borohydride lanthanum complex on a silica surface on the energetic (kinetic and thermodynamic parameters) of the Ring Opening Polymerization (ROP) reaction of ε-caprolactone has been studied in the framework of density functional theory (DFT). For all considered grafted catalysts (monografted, bigrafted, or bigrafted after breaking of a Si-O-Si bridge), it is shown that lanthanum borohydride grafted complexes are efficient in lactone polymerization. Moreover, the reaction pathways (leading to a -CH(2) OBH(2) chain end) are predicted to be energetically similar for the three grafting modes, indicating that all grafted modes can account for the activity for silica treated at 700 °C. The catalytic activity of the grafted complexes is also very similar to that of the homogeneous complexes.     

Structure-based study of antiamyloidogenic cyclic d,l-α-peptides

Protein misfolding and aggregation are the hallmarks of many devastating diseases. We have previously shown that cyclic d,l-α-peptide CP-2 reacts and stabilizes less toxic forms of amyloid β (Aβ), and protects the cells from Aβ-induced toxicity. Here, we performed extensive structure-based studies on CP-2 to elucidate the contribution of each residue to the total antiamyloidogenic activity and determine the interactions that are involved between CP-2 and Aβ. We showed that the hydrophobicity of CP-2 analogs correlates with their antiamyloidogenic potency, however, aromatic interactions are even more important for this activity. The antiamyloidogenic activity of CP-2 analogs also correlates with their ability to self-assemble, as shown by the critical micelle concentration measurements. The cell survival studies performed on rat pheochromocytoma PC-12 cells suggest that incorporation of an additional aromatic residue to the CP-2's sequence increases its protective effect against Aβ42-induced toxicity.     

生物芯片波导共振光散射扫描装置的研制

以光波导(Optical/Light waveguide)作为激发方式,利用共振光散射(Resonance light-scattering,RLS)原理,研制微阵列生物芯片(Microarray)波导共振光散射扫描装置。此装置主要由光源部件、波导激发部件、光电转换部件、机械传动部件和上位机软件组成。其最小扫描分辨率可达5μm,最大扫描范围100 mm。通过使用新的激发方式,有效提高了RLS的信噪比。使用白光作为激发光源,降低了设备的成本。对金纳米粒子标记的单糖芯片、DNA芯片和多肽芯片的检测结果表明,此装置对溶液中的伴刀豆球蛋白凝集素(ConA)和靶标DNA的检出限分别为1 ng/mL和100 pmol/L,对芯片表面固定的多肽的检出限为100 fg,较现有的商品生物芯片扫描仪降低1～2个数量级。本装置结构简单,成本低廉。     

Effect of partial crosslinking on morphology and properties of the poly(β-hydroxybutyrate)/poly(d,l-lactic acid) blends

Poly(β-hydroxybutyrate) (PHB) is a bio-based and biodegradable aliphatic polyester, however its application is limited by some disadvantages such as high price, brittleness, poor processability and low melt-strength due to serious thermal degradation. Partial crosslinking initiated by dicumyl peroxide (DCP) was applied in this work to improve the performance of poly(β-hydroxybutyrate)/poly(d,l-lactic acid) (PHB/PDLLA) blends. The partial crosslinking of the blends and its effect on the properties, morphology, rheology and thermal behavior of the blends were investigated. The tensile strength and impact toughness of the PHB were increased by incorporation of the PDLLA, which were improved further after the partial crosslinking because of an increased compatibility between the PHB and the PDLLA phases. The rheological study revealed that the storage modulus (G′) and complex viscosity (η*) of the blends were increased after addition of the DCP. On the other hand, the crystallization of PHB in the blends was restricted to a certain extent by the formation of partially crosslinked network while its crystal form was not modified.     

菜籽油热氧化过程中荧光光谱特征的变化研究

为探讨菜籽油热氧化过程中荧光光谱特征的变化规律,采用平行因子分析方法结合二维相关技术解析菜籽油的三维同步荧光光谱,并与油脂氧化化学指标进行相关分析。结果表明:菜籽油具有叶绿素a的荧光特征(Δλ=10 nm,λex=674 nm)和叶绿素b的荧光特征(Δλ=60 nm,λex=620 nm);热氧化过程中,产生了(Δλ=60 nm,λex=448 nm)的特征同步荧光峰。双因子的平行因子分析表明:Δλ为10和60 nm的同步荧光光谱分别为第一、第二主要成分,分别对应叶绿素a和油脂氧化产物的荧光特征;随着热氧化时间的延长,叶绿素a的同步荧光强度降低,而油脂氧化产物的同步荧光强度逐渐升高。二维相关分析表明,叶绿素a热氧化速度、叶绿素b热氧化速度、油脂氧化产物生成速度依次降低。代表叶绿素氧化程度的SFI674和代表油脂氧化产物产量的SFI448与油脂氧化化学指标具有良好的相关性。因此,同步荧光光谱可作为衡量食用油热氧化劣变的指标。     

4-羟基苯甲酰肼的红外光谱研究

基于密度泛函理论(Density functional theory,DFT)B3LYP/6-311+G(d,p)及二级微扰理论(Second-order Mller-Plesset,MP2)MP2/6-311+G(d,p)对4-羟基苯甲酰肼分子进行了构型优化,得到了该分子的稳定几何构型,在此基础上对其频率进行了计算和指认,与4-羟基苯甲酰肼的实验谱图比较分析发现,真空分子的羟基、胺基及CH的特征振动频率与实验值相差较大。因此在单晶数据的基础上,增加一个氨气分子,模拟相邻分子对该分子的影响,MP2的计算结果表明,羟基的振动频率与实验值吻合很好,说明相邻分子之间的相互作用不能忽略以及MP2理论在解释该类分子的振动光谱方面具有较高的可靠性。     

甲醛选择性反应探针用于表面增强拉曼散射检测脂多糖

构建了一种依赖于表面增强拉曼散射(SERS)技术检测脂多糖氧化产物甲醛,实现对脂多糖的定量检测。在室温条件下,用NaIO4氧化脂多糖生成甲醛,加入巯基拉曼染料4-氨基-3-肼基-5-巯基-1,2,4-三氮唑(Purpald)与甲醛加合,再加入NaIO4进一步氧化,生成的紫色终产物组装到金纳米颗粒表面,在进行拉曼光谱扫描时产生了SERS增强信号,而在控制实验中没有脂多糖参与时,得到非常弱的SERS信号,由此实现脂多糖的检测。此外,利用紫外可见光谱对脂多糖的氧化产物进行了分析,在540 nm处有甲醛与Purpald加成产物特征的紫外吸收。还对NaIO4、Purpald的反应浓度进行了优化,结果表明,在最优反应条件下,SERS信号随着脂多糖浓度增大而增强,在33～667 mg/L范围内有很好的线性关系,检出限为21 mg/L。本方法无需复杂的实验操作和昂贵的标记试剂。分析速度快,灵敏度高。     

高效液相色谱-串联质谱法测定人体内30种氨基酸

建立了以12种同位素标记氨基酸做内标,采用衍生化方法,LC-MS/MS采用MRM方式同时定量30种氨基酸的检测方法。生物样本加入含有同位素内标的甲醇溶液,沉淀蛋白后氮气吹干加入衍生试剂,样本氨基酸与同位素氨基酸内标同步衍生,减小实验误差。选用TC-C18色谱柱,以水-乙腈(均含有0.01%七氟丁酸和0.1%甲酸)为流动相,采用梯度洗脱进行分离,30种氨基酸及其中的同分异构体都能基线分离。选用3200QTRAP型质谱仪的多重反应监测(MRM)扫描方式进行检测。本方法用于实时监测恶性血液病患者血浆氨基酸谱的变化,可以直接反映机体的代谢及营养状况,对患者的移植成功率及改善移植后患者的生存质量均有重要意义。