水-卵磷脂有序体中的两个热力学常数

卵磷脂(PC)是一种两亲性分子,在水中当超过临界胶束浓度(cmc)以后,呈现一种既有流动性又有有序性的溶致液晶态.它又是脂类生物膜的主要成分,生物物理工作者也常用卵磷脂与水等形成的有序体作为模拟生物膜来研究生物膜的性质.ATP 在生物体中是十分重要的能量传递者,能与许多金属离子结合.Ca~(2+)通过“钙泵”实现跨膜输运.体内碳酸钙等含钙物质的过剩积累会产生各种结石病.了解Ca~(2+)-ATP 在水-卵磷脂有序体中的生成常数K 的变化无疑是有意义的.Mohan 和Rechnitz 已报导了在水溶液中Ca-ATP 生成常数的测定.Amin 等人阐述了胶束中化学反应对生物学的重要意义.Fendler 等人对胶束催化作用有详细沦述.但是前人都未报导当卵磷脂在水中形成有序体时对Ca-ATP 的生成常数     

胆固醇(Cholesterol)嵌入卵磷脂(PC)有序体后对其中CaCO3晶型结构的影响

在PC和Chol/PC有序体中进行CaCO₃沉淀反应,用X射线衍射和扫描电镜方法表征了反应物结构,研究了作为有机模板剂的不同分子有序体对CaCO₃的晶型和形态的指导作用.在反胶束合成中出纳米级CaCO₃颗粒.胆固醇对有序体有显著影响,进而影响此体系中形成的CaCO₃晶型,可诱导生成3种CaCO₃异构体:胶体CaCO₃、球霰石和方解石.方解石含量随胆固醇含量增加减少.     

乳状液法制备憎液溶胶Ⅰ.BaCO_3均匀粒子的制备

均匀胶体粒子的形成，除与反应条件（反应物浓度、陈化时间和温度、介质种类等）有关外，反应体系的环境也影响最终产物的形态，《至结晶结构．气溶胶法和微乳液法正是利用微环境中的‘水池效应”；分别制备出球形亚微米和纳米级的均匀粒子［‘－‘］、这些方法与水解法和相转化法等方法比较，反应物浓度要大几个数量级，而反应时间却短很多，因而受到研究人员的关注．乳状液也能提供亚微米、微米及以上级的微环境，因此，可以应用O／W乳状液乳液中的聚合反应制备亲液的分散体系．然而，极少有关利用w／O乳状液制备僧液溶胶的报导问；最近…     

焦磷酸钠对液相碳化法制备纳米碳酸钙形貌的影响

利用液相碳化法制备了不同形态的纳米碳酸钙颗粒，用TEM、XRD和IR等手段分析表征了纳米碳酸钙的形态和结构，研究了焦磷酸钠对液相碳化法制备纳米碳酸钙合成过程及颗粒形态结构的影响规律。结果表明反应温度是影响纳米碳酸钙形态的关键因素，温度升高时纳米碳酸钙由立方形转变为纺锤形。焦磷酸钠能够促进碳酸钙的晶体成核，抑制晶体生长，在碳化温度大30 ℃时生成链状和棒状的纳米碳酸钙。另外，还分析了链状和棒状纳米碳酸钙的形成机理。     

表面活性剂对纳米CaCO3形貌的调控

分别在AOT／异辛烷／水、CTAB／环己烷／水和OP-10／环己烷／水三种不同的反胶束体系中合成出具有不同形貌的纳米碳酸钙，讨论了表面活性剂的类型以及溶剂热过程对纳米碳酸钙的形貌及尺寸的影响．     

氧化锌-银复合纳米粒子的制备：吸收光谱和荧光光谱

金属和半导体纳米粒子的制备及性质的研究是当今材料科学和物理化学的热门课题［1－6］．在利用太阳能光降解环境污染物、生物传感器以及光生物等方面这些纳米粒子都具有实际应用的可能性．对纳米粒子表面进行修饰而形成的复合纳米粒子可以有效地调整单一颗粒的表面性质甚至颗粒的稳定性．另外，复合纳米粒子的制备对研究纳米粒子的尺寸量子化效应、非线性光学性质及其它光电性质都有重要的意义．人们已成功地制备了许多复合金属－金属纳米粒子，如Cu－Ag［7］，Ag-Pd［8］及Ag－Pt［9］等．关于复合半导体－半导作纳米粒子也有报导，如C…     

大粒径单分散金纳米粒子的水相合成

近年来,随着纳米科技的兴起,纳米尺度的金颗粒以其独特的光学、电学性质［１-３］在许多领域表现出潜在的应用价值,引起了人们浓厚的研究兴趣［４-７］．迄今为止,已有多种制备金纳米粒子的方法见诸报导．制备简便、单分散性好、粒径可控,一直是各种方法追求的目标．...     

纳米ZnO颗粒在阳极Al2 O3模板中的强光致发光研究

用金属醇盐水解法在阳极Al2O3模板的有序孔洞中生长了纳米量级的ZnO颗粒,并用扫描电子显微镜(SEM)和高分辨电子显微镜(HRTEM)对其形貌进行观察.对纳米ZnO/多孔阳极Al2O3模板组装体的光致发光谱进行测量,将组装体中纳米ZnO颗粒的发光强度与常规方法制备的纳米ZnO颗粒发光强度做了比较,就发光强度提高的原因进行了讨论.     

烷基胺作为络合剂制备亲油性纳米银

在烷基胺/油酸/水混合体系中制备出表面包裹的亲油性纳米银颗粒,体系中的烷基胺作为络合剂和稳定剂起到使Ag离子水溶液与油酸互溶的作用,在还原过程中均匀释放出Ag离子,使Ag表面被油酸包裹具有亲油性。在相同反应条件下,分别以环己胺、正丁胺、三乙胺作为络合剂,考察了不同结构的胺对纳米Ag的形成过程以及对纳米Ag的表面性质和形貌的影响,并考察了所得纳米Ag颗粒的热稳定性。结果表明,相同反应条件下,正丁胺和三乙胺比环己胺更适于作为络合剂和稳定剂来制备油酸包裹的亲油性纳米Ag,所制备的纳米Ag颗粒在烷烃等中具有较好的热稳定性。     

St/交联剂乳液共聚包覆硬脂酸改性碳酸钙颗粒的研究

在硬脂酸改性的纳米碳酸钙存在下,通过苯乙烯(St)与多乙烯基单体的乳液共聚合,制备了以纳米碳酸钙为核,以交联聚苯乙烯(PS)为壳的交联型PS/碳酸钙复合纳米粒子.研究了多乙烯基单体的种类和用量以及碳酸钙的用量对聚合反应以及包覆的影响.结果表明,多乙烯基单体以及碳酸钙的引入会使聚合反应速率有不同程度的降低;使用1%~5%的TMPTMA或DVB,可实现PS对碳酸钙颗粒的牢固包覆,不可抽提的PS达94%以上;当碳酸钙用量改变时,需要适当调整乳化剂和多乙烯基单体的用量;IR和TGA的结果表明,随着碳酸钙用量增加,产物中的碳酸钙含量也相应增加;TEM照片和计算结果显示,当碳酸钙用量为14.8%时,绝大部分碳酸钙颗粒被包覆,且基本上每个乳胶粒中包覆一个碳酸钙颗粒,复合粒子具有清晰的核壳结构,壳层厚度约为10 nm,而当碳酸钙用量增加到29.3%和58.7%时,壳层厚度减小,并且出现较多裸露的碳酸钙颗粒.     

Kinetic studies of the interaction of fatty acids with phosphatidylcholine vesicles (liposomes)

The kinetics of addition of fatty acids (as alkaline solutions of the fatty acid anions) to pre-existing unilamellar phospholipid vesicles (mean diameter 100 nm) has been studied. The phospholipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) has been mainly used, together with three fatty acids, oleic acid (cis-9-octadecenoic acid), linoleic acid (cis,cis-9,12-octadecadienoic acid) and capric acid (decanoic acid). Experiments were performed above as well as below the main phase transition temperature (Tm) of DMPC vesicles. The pH chosen to study the fatty acid vesicle interaction (after fatty acid and vesicle mixing) was 8.5 in the case of oleic acid and linoleic acid and 7.4 for capric acid. In the absence of any pre-existing phospholipid vesicles, the addition of alkaline solutions of the fatty acid anions to corresponding buffer solutions of pH 8.5 or 7.4 leads to a partial protonation of the fatty acid anions again resulting in the formation of fatty acid vesicles. This process is rather slow, taking place over a period of hours/days, and the vesicles formed are very polydisperse and include a range of vesicle sizes/shapes. However, in the presence of pre-existing phospholipid vesicles the added fatty acids equilibrate readily within a few minutes and the size of the vesicles that form are then closely related to the size of the originally present phospholipid vesicles; the vesicles formed being generally somewhat larger than the pre-existing vesicles. In the case of the phospholipid DMPC, the mixed fatty acid/phospholipid vesicle system is often formed rather rapidly (particularly above Tm), so that stopped-flow methods have been applied to follow the kinetics of the process. It is proposed that most of the fatty acid molecules are initially rapidly incorporated into the bilayers of the pre-exisiting phospholipid vesicles as monomers, rather than that the added fatty acids form separate fatty acid vesicles. The mean vesicle sizes formed in the systems investigated have been analysed by using dynamic light scattering measurements. The behaviour of the DMPC system was found to be slightly different from the POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) system studied before, but the results are consistent with a model that involves growth and subsequent fission of the mixed vesicles. The study provides further support of the "matrix effect" in this type of system [S. Lonchin, P.L. Luisi, P. Walde, B.H. Robinson, J. Phys. Chem. B 103 (1999) 10910-10916]. The pre-existing DMPC vesicles act as a kind of seed to control the behavior of the system in the presence of added fatty acid anions.     

New vesicle formation upon oleate addition to preformed vesicles

The size distribution of new vesicles formed after addition of oleate in different forms to preformed egg yolk phosphatidylcholine (EggPC) vesicles was studied by gel exclusion chromatography. The addition of oleate to preformed vesicles resulted in the formation of new small vesicles. Fission of preformed vesicles incorporated by oleate and partial solubilization of the vesicles by addition of oleate in micellar form were involved in the process of the new small vesicle formation.     

苯、甲苯、一氯代苯对含水卵磷脂液晶结构影响的SAXS研究

苯及其衍生物甲苯,一氯代苯都是重要的有机试剂和化工原料,也是对人体有害的有机物。为了了解这些有机试剂对处于生物液晶态的生物膜毒害的机理,我们以含水卵磷脂组成的液晶体系作为人工模型用小角X射线散射(SAXS)方法探讨这些有机试剂对它们结构的影响。关于苯或其它非极性有机介质与含水卵磷脂形成液晶体系及其结构模型前人有一些报导。     

NaCl、KCl、Na2CO3、K2CO3等电解质溶液对含水卵磷脂液晶结构影响的SAXS研究

This paper describs the structural character of liquid-crystal of 5%H_2O-egg yolk phospholipid (PC) containing in avarious salt's solution, the layer distance was determined by means of SAXS method. Experimental results show that the layer distance of liquid crystal phase is increased in the 5%H_2O-PC system as the amount of solution of NaCl or KCl is increased. But on the addition of Na_2CO_3 or K_2CO_3 solution into the 5%H_2O-PC system the layer distance of liquid-crystal phase is held constant. It is considered that Na_2CO_3 or K_2CO_3, might be hydrolyzed producing OH~- ions, so that the latter could stablize the interfacial potential between water and egg yolk phospholipid. Absence of this behavior for solution of NaCl or KCl might be due to NaCl and KCl are salts which formed by strong acids and strong bases.     

NaCl、KCl、Na_2CO_3、K_2CO_3等电解质溶液对含水卵磷脂液晶结构影响的SAXS研究

关于电解质溶液对卵磷脂液晶结构的影响前人有过报导。例如Chapman和G. Shiply等在研究碱金属氯化物对卵磷脂液晶结构的影响时指出:随着Li~ 到Cs~ 离子半径增加,脂双层的厚度也发生相应变化。Plainer等也指出KCI,NaCl溶液使磷脂层厚度发生变化。关于磷脂蛋白复合膜与Na~ ,K~ 、Ca~(2 )离子的作用也有一些报导。本文报导用小角X射线散射(SAXS)方法研究几种电解质溶液对卵磷脂形成液晶结构的影响。     

Stability of phospholipid vesicles studied by asymmetrical flow field-flow fractionation and capillary electrophoresis

The stability of zwitterionic phosphatidylcholine vesicles in the presence of 20 mol% phosphatidyl serine (PS), phosphatidic acid (PA), phosphatidyl inositol (PI), and diacylphosphatidyl glycerol (PG) phospholipid vesicles, and cholesterol or calcium chloride was investigated by asymmetrical flow field-flow fractionation (AsFlFFF). Large unilamellar vesicles (LUV, diameter 100 nm) prepared by extrusion at 25 °C were used. Phospholipid vesicles (liposomes) were stored at +4 and −18 °C over an extended period of time. Extruded egg yolk phosphatidylcholine (EPC) particle diameters at peak maximum and mean measured by AsFlFFF were 101 ± 3 nm and 122 ± 5 nm, respectively. No significant change in diameter was observed after storage at +4 °C for about 5 months. When the storage period was extended to about 8 months (250 days) larger destabilized aggregates were formed (172 and 215 nm at peak maximum and mean diameters, respectively). When EPC was stored at −18 °C, large particles with diameters of 700–800 nm were formed as a result of dehydration, aggregation, and fusion processes. In the presence of calcium chloride, EPC alone did not form large aggregates. Addition of 20 mol% of negatively charged phospholipids (PS, PA, PI, or PG) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) vesicles increased the electrostatic interactions between calcium ion and the vesicles and large aggregates were formed. In the presence of cholesterol, large aggregates of about 250–350 nm appeared during storage at +4 and −18 °C for more than 1 day.

The effect of liposome storage temperature on phospholipid coatings applied in capillary electrophoresis (CE) was studied by measuring the electroosmotic flow (EOF). EPC coatings with and without cholesterol, PS, or calcium chloride, prepared from liposomes stored at +25, +4, and −18 °C, were studied at 25 °C. The performances of the coatings were further evaluated with three uncharged compounds. Only minor differences were observed between the same phospholipid coatings, showing that phospholipid coatings in CE are relatively insensitive to storage at +25, +4 °C or −18 °C.     

二价金属离子对磷脂聚集体的影响

通过浊度分析和激光光散射光谱研究了二价金属离子（Ca2＋、Cu2＋和Mn2＋）对蛋黄卵磷脂(EYPC)聚集态的影响.结果表明，自由的二价金属离子对EYPC囊泡有破坏作用,并使EYPC囊泡发生相转变,形成胶束;而与牛磺胆酸钠(TC)结合的二价金属离子使EYPC囊泡半径减小,但不破坏EYPC囊泡.     

SiO_2包覆超细CaCO_3的微晶分析和XPS研究

0引 言 超细碳酸钙在橡胶、塑料、造纸、涂料、油墨、医药、化妆品等工业中有广泛应用。碳酸钙粉末表面具有许多水羟基,表面是亲水疏油性的 ,易形成聚集体 ,分散性能差 ,直接应用效果不好。因此,根据其本身的性质及其应用目的,对其进行表面处理,以相应提高其应用性能。碳酸钙的表面处理是通过物理或化学方法将表面处理剂吸附或反应在碳酸钙的表面,形成表面改性层,使其表面活性化,以改善碳酸钙的表面性能。目前碳酸钙的表面改性大多为有机表面改性、偶连剂表面改性、高分子（聚合物）表面改性等 [1],而无机表面改性却很少有报道。我…     

Effect of freeze-thawing and polyethylene glycol (PEG) lipid on fusion and fission of phospholipid vesicles

The effect of freeze-thawing on the size of egg yolk phosphatidylcholine (EggPC) vesicles in the presence of 0-40 mol% distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG) was studied. Mean diameters of the vesicles fell into a range of 80-150 nm after 10 times freeze-thawing in spite of their original size. In the process of freeze-thawing, two opponent events, one is fission and the other is fusion, occurred at the same time. DSPE-PEG accelerated the fusion event.     

Size control of mixed egg yolk phosphatidylcholine (EggPC)/oleate vesicles

The size distribution after addition of oleate surfactant to preformed Egg yolk phosphatidylcholine (EggPC) vesicles was investigated by gel filtration chromatography combining with dynamic light scattering. Phospholipid and oleate concentration, fluorescence intensity and size of the vesicles were measured for each elution fraction. The spontaneous vesiculation of oleate at pH 8.5 was accelerated in the presence of preformed EggPC vesicles. The size distribution of newly formed vesicles was dependent on the preformed vesicular size. For example, oleate addition to large preformed vesicles (230 nm) resulted in altering of vesicles to both larger and smaller than preformed ones, while addition of oleate to small preformed vesicles (50 nm) led to the formation of only larger vesicles without exhibition of newly small vesicles. The combinations of gel filtration chromatography and dynamic light scattering could provide more detailed insight into the size change of newly formed vesicles.