免标记地检测二元磷脂膜中磷脂分布的表面增强拉曼成像方法

以银纳米粒子自组装层为增强基底,我们报道了一种用于检测二元磷脂膜中具有相似结构磷脂分布的表面增强拉曼成像方法,这种方法具有免标记及花费低廉的优点.对探针分子对巯基苯胺（p-aminothiophenol）,实验中所用的银纳米粒子自组装层表现出强的表面增强拉曼活性及良好的重现性.原子力显微镜表征结果证明了完整的磷脂膜在银纳米粒子自组装层上的形成.以这种银自组装层为基底,我们得到了磷脂膜中二肉豆蔻酰磷脂酰甘油（DMPG）和二肉豆蔻酰磷脂酰胆碱（DMPC）的表面增强拉曼光谱,并且利用DMPG的光谱特征峰,1482cm-1,区分这两种磷脂.而通过1482cm-1和1650cm-1的峰强比（R1482/1650）,可以同时得知在混合磷脂膜上某点这两种磷脂所占的比例：R1482/1650值的增加意味着DMPG的增加和DMPC的减少.磷脂膜的表面增强拉曼成像则是由R1482/1650值和对应的位置信息组合而得到,其成像结果表明了带电的磷脂DMPG在混合磷脂膜中的聚集.我们所报道的基于表面增强拉曼成像技术的方法提供了一种便利的、免标记的和花费低廉的途径来研究磷脂膜的结构,例如磷脂域和脂阀.     

金纳米粒子在氨基表面上的组装-pH值的影响

用原子力显微镜（AFM）和表面增强喇曼光谱（SERS）研究了pH值对金纳米粒子在Au／巯基苯胺自组装膜表面上组装效果的影响．AFM结果表明，金纳米粒子在表面上的覆盖度随pH值表现出规律性的变化，巯基苯胺自组装膜的SERS强度随pH值的变化也有类似的趋势．在磁性环境下，氨基未质子化，金粒子难以组装上，而在酸性条件下，氨基质子化带正电，金粒子与基底容易结合．我们认为金纳米粒子和氨基之间的作用属于静电力，pH值同时影响膜表面氨基的质子化程度和金纳米粒子表面的带电量．     

磷脂膜的相行为对氧化石墨烯与磷脂膜相互作用的影响

通过使用不同相变温度的磷脂分子并调节二者的比例构筑了不同相态的磷脂膜, 并利用表面增强红外光谱和激光共聚焦显微镜研究了磷脂膜的相行为对氧化石墨烯和磷脂膜相互作用的影响. 结果表明, 氧化石墨烯对磷脂膜中磷脂分子的抽提作用具有显著的相态选择性, 其选择性地抽提流动相的磷脂分子; 氧化石墨烯对流动相磷脂的抽提作用受到膜中凝胶相磷脂存在比例的影响, 只有在流动相磷脂分子占磷脂膜中磷脂分子的绝大部分时才能够发生抽提作用, 且只有流动相的磷脂分子被抽提.     

毒素蛋白ColicinE1与磷脂膜相互作用的荧光光谱研究临界摩尔比的测定

磷脂－蛋白相互作用的临界摩尔比是研究膜脂－蛋白相互作用的重要参数．本文利用荧光光谱技术首次测定了毒素蛋白ＣｏｌｉｃｉｎＥ１在不同条件下与不同磷脂膜相互作用的临界摩尔比并通过临界摩尔比的变化讨论了插膜蛋白与磷脂膜相互作用的规律，为进一步探讨毒素蛋白的插膜机制提供了重要的基础     

磷脂膜色谱及其在药物跨膜转运评价中的应用

磷脂膜色谱是固态基质上的有序磷脂分子单层体系采用色谱学方法仿真药物与细胞膜相互作用过程,可用来评价药物的细胞膜渗透性和活性。硅胶表面上的磷脂单分子层模拟了单层细胞膜,因此药物的磷脂膜色谱保留行为可用于预测药物与细胞膜的相互作用。目前考察药物跨膜转运的模型主要有正辛醇/水系统、脂质体/水系统、反相色谱（ODS）以及磷脂膜色谱。与前述3种系统比较,磷脂膜色谱除了具有高效、简便等特点外,同时能模拟药物与生物膜之间疏水作用力以外的其他作用力,因此对磷脂膜色谱的研究也越来越深入。由于药物细胞膜渗透性对其有效性和安全性起着关键作用,因此磷脂膜色谱在新药研发早期阶段的介入可以有效地降低后期候选药物的淘汰率,提高新药的研发效率。该文就磷脂膜色谱的研究及在药物跨膜转运评价中的应用进行了综述。     

孔蛋白-磷脂仿生膜的葡萄糖氧化酶电化学

采用孔蛋白（MspA）和双肉豆蔻磷脂酰胆碱（DMPC）在玻碳（GC）基底表面成功构建有仿生特性的纳米通道膜,同时将葡萄糖氧化酶（GOD）修饰于膜上. 使用循环伏安法研究GOD/MspA-DMPC/GC电极的GOD直接电化学过程以及其对氧气和葡萄糖的响应. 研究发现,MspA与DMPC形成的仿生纳米通道膜内,GOD在接近生物体系FAD/FADH标准电位处实现了自身两质子、两电子表面控制的电化学反应. MspA与DMPC的仿生纳米通道膜体系为GOD提供了理想活性环境.     

毒素蛋白Colicin E1与磷脂膜相互作用的荧光光谱研究——临界摩尔…

磷脂－蛋白相互作用的临界摩尔比是研究膜脂－蛋白相互作用的重要参数。本文利用荧光光谱技术首次测定了毒素蛋白Ｃｏｌｉｃｉｎ Ｅ１在不同条件下与不同磷脂膜相互作用的临界摩尔比并通过临界摩尔比的变化讨论了插膜蛋白与磷脂膜相互作用的规律，为进一步探讨毒素蛋白的插膜机制提供了重要的基础。     

非支撑磷脂双层膜制备及温度对其力学性质的影响

结合聚苯乙烯球刻蚀和微机电系统技术加工氮化硅纳米多孔膜, 并在其上用囊泡法制备非支撑磷脂双层膜, 通过温控原子力显微术(AFM)的成像模式和力曲线模式对非支撑磷脂双层膜的形貌和力学性质进行研究. 实验结果表明, 该方法制备的非支撑磷脂双层膜具有流动性, 能进行自我修复, 该特点有利于提供足够的非支撑磷脂双层膜区域用于其性质研究; 非支撑磷脂双层膜的膜破力和粘滞力均随着温度的升高而减小, 即膜的机械稳定性随着温度的升高而降低. 非支撑磷脂双层膜膜破力小于支撑磷脂双层膜的膜破力, 并且非支撑磷脂双层膜粘滞力随温度的变化趋势与支撑磷脂双层膜的变化趋势相反.     

盐溶液中磷脂膜的组装及电场诱导的结构转变

在与生理介质等渗的盐溶液中，借助于原子力显微镜（AFM）和荧光漂白恢复（FRAP）技术，分别研究了中性磷脂和带电磷脂在高定向热解石墨（HOPG）表面上的分子排列、组装以及施加电场对其结构的诱导变化。结果表明，所考察的磷脂在室温下均以凝胶态的单层膜形式铺展在HOPG上，并组装形成纳米尺度的半胶束结构，表面呈现波纹形貌。施加适度的电场（±1.0 V）在诱导磷脂分子的排列和结构发生转变时起主要作用，界面溶剂化力和离子效应起次要作用。研究结果对生物电化学功能器件的模拟以及基于磷脂的实验室芯片开发等具有重要意义。     

表面修饰富勒烯的聚酰胺-胺树枝状分子与生物膜的相互作用研究

采用粗粒化的分子动力学模拟,研究了末端修饰富勒烯(C60)的聚酰胺-胺(PAMAM)树枝状分子在水溶液中的结构变化以及其与磷脂膜相互作用行为.发现修饰后的PAMAM分子大小随嫁接数目的增多而减小,而形状变化并不明显,分子仍是近球形结构;同时发现C60分子因疏水作用聚集在一起.与膜作用后,因C60分子插入到双层膜内,导致分子由球形稍微向椭球形改变,分子大小也稍微增大.同时发现PAMAM分子紧紧分布在磷脂膜表面,局域膜厚度变小.     

Studies on the biomimetic membrane interaction between liposome and realgar nanoparticles

The liposome of small unilamellar vesicles (SUV) made from phosphatidylcholine-cholesterol mixtures was used as a simple model for biomimetic membranes. The studies on the interaction between the liposome and realgar nanoparticles (NPs) demonstrate that the phospholipid is one of the key targeted molecules of realgar NPs, used by surface plasmon resonance (SPR) technology, fluorescence polarization, Raman spectroscopy, nuclear magnetic resonance (NMR) and atom force microscope (AFM). It was observed that th...     

Cesium's Affects on Morphological Changes of Human Erythrocytes

Cesium could play a toxic role in several pathological processes. Atomic force microscopy (AFM) was used to study morphological changes of human erythrocytes after incubating with different concentrations of CsCl, and the Raman spectra were used to study the effects of CsCl on the chemistry components of erythrocyte membrane. The AFM images showed that the "domain structures" that appeared after incubation with higher concentration of CsCl (150 mmol·L^?1), are featured by the particles aggregated to form ranges and the separations among them enlarged to gorges, and this change may increase the permeability of cell membranes. The Raman results showed that the polar part of membrane phospholipid become more order and with the increasing of the concentration of CsCl, the longitudinal order of nonpolar parts first decreased and then increased. It is concluded that the aggregation of membrane proteins and the order changes of the phospholipid cause a change in the distribution and conformation of the phospholipid membrane. And the effects of CsCl on the erythrocyte membrane are mainly dependent on its concentration.     

Kinetics and enthalpy measurements of interaction between beta-amyloid and liposomes by surface plasmon resonance and isothermal titration microcalorimetry

The objective of this research is to understand the interaction mechanism of β-amyloid (Aβ) with cell and were basically divided into two parts. The first part focused on the time-dependent structural changes of Aβ (1-40) by circular dichroism (CD) spectroscopy, thioflavin T (ThT) fluorescence assay, and atomic force microscopy (AFM). The second part emphasized the kinetics and enthalpy of interaction between Aβ (1-40) and liposome by surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). Results obtained from CD, ThT and AFM confirmed the formation of 1 μm fibril after single day incubation. The driving force of kinetic interaction between Aβ and liposomes was revealed by SPR to be electrostatics. Further studies indicated that fresh Aβ has high GM1 affinity. Besides, addition of cholesterol to the liposome could alter membrane fluidity and affect the interactions of fresh Aβ with liposomes especially in the amount of Aβ absorbed and preserving the structure of liposome after adsorbing. Hydrophobicity was found to be the driving force leading to the interaction between Aβ fibrils and liposomes. These reactions are endothermic as supported by ITC measurements. When the composition of liposomes is zwitterionic lipids, the interaction of Aβ with liposomes is predominantly hydrophobic force. In contrast, the driving force of interaction of charged lipids with Aβ is electrostatic.     

二氧化铈纳米微粒过氧化物酶活性及其在葡萄糖检测中的应用

合成了一种稳定和水溶性的聚丙烯酸修饰CeO2 NPs,利用动态光散射(DLS)、傅里叶变换红外光谱(FT-IR)和X射线光电子能谱(XPS)进行表征.结果表明,CeO2 NPs能够催化H2O2氧化3,3′,5,5′-四甲基联苯胺(TMB)发生显色反应,表现出过氧化物模拟酶催化活性.利用Raman和顺磁共振(EPR)光谱技术研究了其催化机理.基于CeO2 NPs催化TMB变色反应对H2O2浓度的依赖性和葡萄糖氧化酶能够催化溶解氧氧化葡萄糖产生H2O2的原理,构建了一种简单、灵敏、选择性高的测定血清中葡萄糖的检测方法.在优化条件下,测定葡萄糖的线性范围为0.5~10 mmol/L,检出限(3σ)为0.1 mmol/L.对1.0 mmol/L葡萄糖进行11次平行测定,其相对标准偏差为2.4%.该方法已成功用于血清样品中葡萄糖的测定.     

铝纳米粒子表面引发聚合制备核壳纳米结构

利用硅烷偶联剂引发法制备核壳结构金属铝纳米粒子(Al NPs)@聚合物, 并研究了聚合反应时间和单体浓度对核壳结构尺寸的影响. 首先合成了硅烷偶联引发剂{2-溴-2-甲基-[3-(三甲氧基硅基)丙基]丙酰胺}, 并通过在甲苯中回流的方法, 将其锚定在金属铝纳米粒子表面. 然后, 在粒子表面引发甲基丙烯酸甲酯的原子转移自由基聚合, 形成聚甲基丙烯酸甲酯(PMMA)壳层. 通过核磁共振波谱仪(NMR)和傅里叶变换红外光谱仪 (FTIR)证明了引发剂和PMMA的成功接枝. 透射电子显微镜(TEM)图像表明, PMMA改性后的金属铝纳米粒子的尺寸和形貌基本不变, 且被厚度约为15 nm聚合物壳层完整均匀地包覆. 此外, 利用动态光散射(DLS)进一步揭示了聚合时间和单体浓度对核壳结构水合直径(D_h)的影响, 发现延长聚合时间或增加单体浓度均可显著提高核壳结构尺寸.     

包覆NIPAM-ODA双亲共聚物的脂质体的温控释放行为

为了研究对温度敏感的双亲性共聚物包覆的脂质体的温控释放行为,合成了N-异丙基丙烯酰胺(NIPAM)和丙烯酸十八酯(ODA)的共聚物。利用荧光探针法研究了共聚物水溶液随温度升高时出现的LCST(lower critical solution temperature)现象,表明该高分子在温度升高到30℃以上时存在着明显的相分离行为。5(6)-羧基荧光素(5(6)-CF)为标记物,研究了高分子包覆的小单层脂质体(small unilamelar vesicles)的释放行为。发现在温度低于30℃时,5(6)-CF的释放百分率比未包覆高分子的脂质体要低;而当温度升高到30℃以上时,其释放百分率明显提高。这种温控释放行为和包覆在脂质体上的高分子在其LCST时存在的相分离行为有关。进一步利用荧光偏振法研究了脂质体膜在包覆高分子后的流动性变化,发现:在温度低于30℃时,其流动性随温度升高而增大;而在温度高于30℃时,脂质体膜流动性随温度升高而降低,进一步证实了高分子在其LCST以上时对脂质体膜的破坏作用。     

Biomembrane Interactions of Functionalized Cryptophane‐A: Combined Fluorescence and 129Xe NMR Studies of a Bimodal Contrast Agent

Fluorescent derivatives of the ¹²⁹Xe NMR contrast agent cryptophane‐A were obtained by functionalization with near infrared fluorescent dyes DY680 and DY682. The resulting conjugates were spectrally characterized, and their interaction with giant and large unilamellar vesicles of varying phospholipid composition was analyzed by fluorescence and NMR spectroscopy. In the latter, a chemical exchange saturation transfer with hyperpolarized ¹²⁹Xe (Hyper‐CEST) was used to obtain sufficient sensitivity. To determine the partitioning coefficients, we developed a method based on fluorescence resonance energy transfer from Nile Red to the membrane‐bound conjugates. This indicated that not only the hydrophobicity of the conjugates, but also the phospholipid composition, largely determines the membrane incorporation. Thereby, partitioning into the liquid‐crystalline phase of 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine was most efficient. Fluorescence depth quenching and flip‐flop assays suggest a perpendicular orientation of the conjugates to the membrane surface with negligible transversal diffusion, and that the fluorescent dyes reside in the interfacial area. The results serve as a basis to differentiate biomembranes by analyzing the Hyper‐CEST signatures that are related to membrane fluidity, and pave the way for dissecting different contributions to the Hyper‐CEST signal.     

Interaction between (1,1'-Binaphthalene)-2,2'-diol and Lecithin Liposome

The interaction between (1,1′‐binaphthalene)‐2,2′‐diol (BINOL) and lecithin liposome was studied by UV‐Vis, fluorescence and ¹H NMR spectroscopies. BINOL can obviously associate with lecithin liposome and the preferential binding site of BINOL with lecithin liposome is located in the headgroup region. The hydrogen bond and electrostatic interaction should exist in BINOL/liposome system, which restricts intra‐annular rotation of naphthol moieties. Therefore, the fluorescence intensity of BINOL increases when a small quantity of liposome is added into the system. The partition coefficient K_D between the lecithin liposome and the aqueous phase is 310.9. With the increase of BINOL concentration, the micropolarity (I₁/I₃) and membrane fluidity of liposome decreased, while the viscosity of membrane increased.     

Interaction of pentoxifylline with human erythrocytes. II. Effects of pentoxifylline on the erythrocyte membrane

The effects of pentoxifylline and other hemorheologically active drugs on the human erythrocyte membrane were examined by means of electron spin resonance spectroscopy. It was observed that the fluidity in the region of the phospholipid head groups in the erythrocyte bilayer was increased by an externally added drug. In this region, membrane fluidity was dependent on the incubation time, suggesting an interaction with membrane proteins. On the other hand, the acyl chain motion in the lower portion of the chain, the hydrophobic end, was reduced in the presence of the drugs. In this case, the acyl chain motion was not time-dependent. These changes of the membrane fluidity at different depths of the membrane induced by the drugs may correlate to the erythrocyte deformability.     

液晶态磷脂酰乙醇胺脂质体和LB膜结构的研究

用原子力显微镜、小角X射线散射和³¹PNMR分别对液晶态磷脂酰乙醇胺脂质体和LB膜结构进行了研究.用原子力显微镜观察到了液晶态脂质体的立方相和双层膜共存的结构图像.研究结果表明,两相共存的状态与双亲性分子的结构、浓度以及介质的组分和pH等因素有关.用小角X射线散射和³¹PNMR研究发现,在DEPE液晶态中,钠盐诱导形成Q²²⁹(Im3m)立方相.DEPE液晶态分别在37.5℃出现L_β→L_α可逆相变,在63.5℃出现L_α→H_Ⅱ可逆相变.