仿生信号转导体系的构建:囊泡表面磷脂信号分子诱发的乳酸脱氢酶的激活

以细胞肌醇磷脂信号转导途径为原型,在合成肽脂囊泡(人工细胞膜模型)上,利用天然磷脂为信号分子,成功地激活了处于囊泡表面的乳酸脱氢酶．为此,将1,2-二-十四烷基磷脂酰乙醇胺等天然磷脂嵌入合成肽脂N,N-二-十六烷基-N^a-6-三甲胺基己酰基-L-甘氨酰胺囊泡中,制备了稳定的混合双层膜囊泡,用透射电子显微照相、动态光散射及差示扫描量热等手段确认了混合囊泡的形态及粒径分布．以磷酸吡哆醛等维生素B6类化合物为信号分子激活剂,利用它们与天然磷脂形成复合体,进而与Cu^2 形成强的金属配合物的性质,实现了对处于囊泡表面、被Cu^2 抑制的乳酸脱氢酶的激活,构建了一个新的仿生信号转导体系．紫外一可见光谱实验证实了以上结果．此外,结果还表明囊泡表面的疏水作用和静电引力是促进天然磷脂一磷酸吡哆醛复合体形成的主要因素．囊泡表面的疏水微环境作为反应场是构建此仿生信号转导体系不可缺少的要素．     

共轭亚油酸与海藻酸钠囊泡化自组装纳米容器及其药物缓释性能

脂肪酸囊泡(FAV)是一类重要的纳米容器,然而其形成pH范围较窄且偏碱性环境,限制了其应用。 本文将共轭亚油酸(CLA)与海藻酸钠(SA)在近中性环境下共同自组装囊泡化纳米容器并提高其膜稳定性。动态激光光散射(DLS)和透射电子显微镜(TEM)结果表明,当SA质量分数为25%~50%时复合体系可在近中性条件下自组装形成50~250 nm尺寸的囊泡化纳米容器,且pH=7.4时随着质量分数增加囊泡化纳米容器直径增大。 根据SA和CLA在中性环境的物种存在形式推测,二者通过氢键作用驱动形成囊泡化纳米容器。 体外模拟释放实验表明,囊泡化纳米容器具有较高包覆率和较优缓释效果,有望应用于药物传输领域。     

新型囊泡状二氧化硅中孔分子筛的合成与表征

中孔分子筛能适应人们有效利用重组分油的需要，因此自从1992年美国Mobil公司的研究者们。用烷基季铵盐阳离子表面活性剂做模板剂，合成出M41S系列中孔分子筛之后，中孔分子筛的合成与应用已成为人们研究的热点之一。近几年来。人们根据不同的组装路线，利用不同的表面活性剂做模板剂已合成出多种新型中孔分子筛，如以静电组装路线合成的FSM-16、M41S、SBA-n系列、KIT-1等，以氢键组装路线合成的HMS，MSU-X，MSU-V，MSU-G等。     

电容法研究卵磷脂/氨基酸/H2O胶束和囊泡体系

运用电容法研究卵磷脂/氨基酸/H2O胶束和囊泡体系结构与性质. 卵磷脂的临界胶束浓度和囊泡生成浓度可由体系电容-卵磷脂浓度关系曲线求得.随着卵磷脂浓度增加, 体系电容增加, 卵磷脂由胶束形成囊泡. 随着氨基酸浓度增加, 胶束、囊泡半径增大, 体系电容减小. 氨基酸能促进卵磷脂形成胶束和囊泡, 使得卵磷脂临界胶束浓度和囊泡生成浓度减小, 其影响的强弱顺序为组氨酸>色氨酸>>甘氨酸.     

Self-assembly formation of amphiphilic molecules mixed with photoreactive,aromatic unsaturated-acids: examination by light scattering

Light scattering measurement was carried out for aqueous solutions of amphiphilic molecules mixed with aromatic unsaturated carboxylic acids. Their structures are discussed according to sizes of molecular assemblies evaluated. In aqueous solutions of hexadecyltrimethylammonium hydroxide with 2-indenecarboxylic acid, short rodlike micelles were formed on mixing at a ratio of 11. Particles in aqueous solutions of dodecyldimethylamine oxide and cinnamic acid varied from micelles to vesicles with increasing cinnamic acid concentration. The structures were related to the effective photocyclodimerization of olefins and the stereochemical selectivity of cyclodimers.     

Determination of lecithin and soybean oil in dietary supplements using partial least squares-Fourier transform infrared spectroscopy

Lecithin and soybean oil in dietary supplements were determined by Fourier transform infrared spectrometry transmission measurements in dichloromethane in combination with a partial least squares (PLS) regression. Two different PLS models were developed, using 16 synthetic mixtures of analytes in dichloromethane, making measurements in the spectral range from 931.8 to 1252.3 cm⁻¹ for lecithin and from 911.4 to 1246.9 cm⁻¹ and 1695.3 to 1774.5 cm⁻¹ for soybean oil. Seven products from the Spanish market with lecithin concentrations between 21.1% and 99.1% and soybean oil concentrations between 0% and 37.2% were analyzed by the proposed method and the data was compared to a chromatographic reference procedure obtaining accurate results. For samples spiked with amounts between 50 and 250 mg of lecithin and soybean oil recovery percentages between 98.0% and 102.1% and between 93.6% and 102.0% with an average precision of 0.35% and 0.41% were achieved for lecithin and soybean oil, respectively. This method can be applied for the quality control of dietary supplements.     

Effect of oligonucleotide conformation on its facilitation efficiency on negatively charged micelle‐to‐vesicle transition

In our previous article, we reported for the first time that the oligonucleotides composed of one nucleotide species, for example, oligo d(A)_n, oligo d(C)_n, and oligo d(T)_n, could facilitate negatively charged sodium dodecyl sulfate/dodecyl triethyl ammonium bromide mixed micelles to transform to vesicles. In this study, we will report the facilitation ability of self‐complementary hairpin‐structured oligonucleotides, oligo d(A_nCT_n) and oligo d(AT)_nACT(AT)_n (or oligo d(AT)_nC(AT)_n), on micelle‐to‐vesicle transition. It is found that the facilitation behavior of hairpin‐structured oligonucleotide is different from that of the oligonucleotide comprising one base species, and the facilitation efficiency of hairpin‐structured oligonucleotide is closely dependent on the sequence of bases A and T; oligo d(A_nCT_n) is more efficient than oligo d(AT)_nACT(AT)_n (or oligo d(AT)_nC(AT)_n). Moreover, oligo d(A_nCT_n) is more efficient than oligo d(A)_n, oligo d(C)_n, and oligo d(T)_n. Since so far, there is very limited report about the facilitation effect of oligonucleotide and DNA on vesicle formation as well as the role of their conformation in their interaction with surfactant, this study should be expected to provide some helpful information for the application of DNA/amphiphile system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 852–860, 2010     

多肽诱导的巨型脂质体出芽和泄露行为

细胞膜与膜蛋白之间的相互作用与生命中许多过程息息相关.以巨型脂质体(GUV)和多肽分别作为细胞膜和膜蛋白的简化模型,我们设计了四种仅包含亮氨酸(L)和赖氨酸(K)的多肽,即K₁₄、(KL₂KL₂K)₂、(KL₂KL₃)₂和K₆L₈,并对比研究了它们与中性和负电性脂质体的相互作用.电荷密度最高的K₁₄只是涂层在脂质体表面,不破其囊泡结构,但能够引起负电性脂质体发生微相分离,属建设性相互作用.能够形成两亲性α螺旋的(KL₂KL₂K)₂和(KL₂KL₃)₂则引起脂质体发生泄露和破裂,属破坏性作用.但二者引起泄露的速率在中性脂质体和负电性脂质体中的结果恰好相反,说明泄露分两步进行:表面吸附多肽达到一定浓度,继而对膜进行干扰.表面活性剂型多肽K₆L₈的氨基酸组成与(KL₂KL₂K)₂相同,但K₆L₈只是引起负电性脂质体发生泄露,造成中性脂质体发生外出芽.这些简单氨基酸造成的脂质体的复杂构象变化可以统一用静电和疏水相互作用在膜上的位置和强度来进行解释.这些结论对于深入理解膜蛋白的作用机理是有帮助的.     

Phase Behavior and Rheological Properties of Concentrated Lecithin Aqueous Solutions with Additives

The phase behavior and rheological properties of the concentrated lecithin aqueous solutions were investigated at 37°C. When adding Isopropyl myristate (IPM) to lecithin solutions, besides an anisotropic liquid crystal (LC) phase, an isotropic liquid (L₂) region and an isotropic viscous (I) phase are found. By continuously adding Brij 97, the LC region shifts towards higher water content and the L₂ region is extended to the area of lower IPM concentration, meanwhile the I phase disappears. By analyzing the shear rate (η_γ=0.1) and yield stress (σ₀), adding IPM to lecithin solutions increases the values of η_γ=0.1 and σ₀, and after further adding Brij 97, the η_γ=0.1 and σ₀ decrease dramatically. Notably, different from the lecithin/DDAB/water system studied by Youssry and Montalvo, in lecithin/Brij 97/IPM/H₂O system, at the relatively higher water content area of the LC phase, the water content has little effect on the critical stress. It is also found that the change of dynamic storage modulus (G′) is similar with that of η_γ=0.1 and σ₀ parameters when adding IPM and Brij 97. Maxwell model fitting results show that in the LC phase, the relaxation of the water molecule is prolonged by adding IPM and Brij 97 to lecithin solutions.     

大分子拥挤环境中脂肪酸影响磷脂囊泡相变的差示扫描量热研究

脂肪酸诱导的磷脂膜的热力学行为对于认识细胞内复杂的机制有着重要意义,而前人在研究脂肪酸与磷脂膜相互作用时大都在稀溶液中进行;拥挤环境下脂肪酸诱导磷脂膜的相变行为还未见报道。本文以二肉豆蔻酰磷脂酰胆碱(DMPC)构建囊泡模型,采用差示扫描量热法系统地研究了在不同浓度、不同分子量的聚乙二醇(PEG)拥挤环境中不同结构的脂肪酸对DMPC磷脂囊泡相变的影响。研究结果表明,在拥挤环境中,PEG对纯的磷脂囊泡相变的影响与大分子的分子量和浓度相关。对于脂肪酸/磷脂囊泡(FA/DMPC),PEG的存在对囊泡相变产生显著影响。在所考察的分子量和浓度范围内,PEG使FA/DMPC囊泡相变增加。短链饱和脂肪酸、不饱和脂肪酸原本使DPMC囊泡相变降低,但PEG缩小了降低幅度,甚至导致相变增加。进一步的研究表明,在大多数情况下,PEG对FA/DMPC的相变具有协作增强效应,且其影响均与大分子的分子量和浓度相关。另外,随着PEG浓度的升高,磷脂囊泡的协同单位数逐渐降低,表明拥挤环境会影响磷脂双分子层的均一性,使协同发生相变的分子数降低。本文的研究表明,大分子拥挤环境能够对扰动的磷脂双分子层起到一定的修复作用,这一现象在生物膜相关领域不可忽视。