【作者】 唐宇峰；

【导师】 沈玉华； 谢安建；

【作者基本信息】 安徽大学 ， 无机化学， 2005， 硕士

【摘要】 单分子膜和LB膜所具有的物理结构和化学性质与生物膜很相似,具有极好的生物相容性,能把功能分子固定在既定的位置上,因而单分子膜和LB膜被用作生物细胞膜的简化模型,可以有效的模拟生物膜。由于构成单分子的表面活性剂分子处于固态膜的状态,分子间彼此紧密排列,利用基底膜的刚性可以有效地控制晶体的成核生长,这不仅为制备新型无机功能材料和生物材料开辟了新的途径,而且对于生物矿化机理的探讨和研究也具有重要的理论意义。此外,将表面活性剂稳定的纳米粒子铺展于亚相表面,然后利用LB技术将其转移到固体基片上,为我们构造超晶格结构提供了一种全新途径。 根据上述思路本论文工作可分为四个部分: 第一部分:胆红素/胆固醇混合单分子膜的制备及性质研究;第二部分:DPPC/胆红素混合体系的成膜性能探讨;第三部分:利用LB技术制备了有机包裹硫化银纳米粒子的有序薄膜;第四部分:花生酸单分子膜为模板制备Ag/Cd双金属硫化物(AgxCdyS)。主要内容如下: 1.我们在LB槽中制备了钙离子亚相上胆红素/胆固醇的混合单分子膜,通过分析不同浓度钙离子亚相上胆红素/胆固醇混合膜π-A曲线可知,在钙离子亚相上胆红素和胆固醇的互溶性与纯水亚相相比发生改变,且随钙离子浓度增大相互间互溶程度下降,在界面上形成非理想混合单分子膜。这种混合膜的非理想性在混合单分子膜的超额单分子面积上表现的非常明显,不同比例混合膜的超额单分子面积与理想混合时相比有明显的正偏差。亚相中的钙离子通过与胆红素及胆固醇配化,改变了二者在气液界面上的取向,并且配位结构较为稳定,不易随膜压发生改变。不同亚相上混合膜可压缩系数的研究变化表明:钙离子对胆红素和胆固醇的成膜性能影响恰恰相反,钙离子促使胆红素单分子膜凝聚而使胆固醇单分子膜凝聚性降低。从胆红素/胆固醇混合单分子膜的超额混合自由能可知,由于钙离子的存在,不同组分分子间的自发混合过程受到阻碍,不同分子间相互聚集作用大为减弱。混合单分子膜的混合自由能在钙离子亚相上出现负偏差,随亚相钙离子浓度的增大,负偏差逐渐减小,膜的热力学稳定性变差,导致同一混合比下混合膜的崩溃压逐渐降低。更多还原

【Abstract】 The monolayer and LB films are used as the simple model of biological membrane because of their similar structures and properties to the membrane, excellent biological miscibility and placing the functional molecules in the established location. When the monolayer is in solid state, the rigid packed molecules can control the growth of crystal. The results are helpful to understand the formation mechanism of biology mineralization. Otherwise, the exceed crystal lattice structure of surfactant-capped nanoparticles has been fabricated by spreading the particles onto the air/water interface and transferring the monolayer onto substrate.Based on these considerations, the dissertation consists of four parts, which include the preparation and properties of bilirubin/cholesterol mixed monolayer and DPPC/bilirubin mixed monolayer, the preparation of monolayer and LB film of the surfactant-capped Ag₂S particles, and the biomimetic synthesis of AgxCdyS particlesunder arachidic acid monolayer.1. From a detail analysis of surface pressure-area isotherms of mixed bilirubin/cholesterol monolayers, it is concluded that the miscibility of bilirubin and cholesterol decreased with the increase of the concentration of Ca²⁺ in subphase. The non-ideality of mixed monolayers is evident in the mean area-composition and the collapse pressure-composition figures. The mixed monolayers exhibited noticeable negative deviation on pure water and positive deviation on Ca²⁺ subphase. It suggests that the attractive interactions between bilirubin and cholesterol should be displaced by the multi-interaction among Ca²⁺, bilirubin and cholesterol. So the molecular packing of bilirubin/cholesterol monolayers is hindered on Ca²⁺ subphase because of the coordination between Ca²⁺ and the components. Furthermore, curves of the free energy of mixing and the excess free energy of mixing to composition indicate that the mixed monolayers become less stable as the concentration of Ca²⁺ increased in subphase.2. In order to get an insight into the mechanism of action between lipid and bilirubin, we undertake the study on the DPPC/BR binary system at the air/water interface. The interactions between DPPC and BR within the monolayer arecharacterized by n-A isotherms, compressibility modulus, mixed free energy, etc.. The conclusions are as listed below:DPPC and BR were miscible and formed non-ideal monolayers at the air/water interface; the attractive interaction between hydrophilic groups is dominant in the molecular packing of mixing monolayers. Owing to the strong hydrogen bonds between the polar groups of DPPC and BR, the stable 1:2 stoichiometry complex （MD_B） can be organized self-assembly at the air/water interface. In addition, the properties of DPPC/BR mixed monolayers were nearly correlative to the subphase pH and calcium ions in subphase. DPPC monolayer becomes condensable on acid aqueous subphase, but its monolayer on alkali aqueous subphase is no difference comparing with it on pure water; the BR monolayer has no apparently change on acid aqueous subphase, but the BR molecules nearly can’t form stable monolayer on basic aqueous solution. Thanks to the hydrogen bonds between DPPC and BR, the mixed monolayer is affected more conspicuously by OH" than by H+. On Ca2+ subphase, pure DPPC and pure BR monolayers became condensed comparing with that on pure water. However, the mixed DPPC/BR monolayer became a little expanded.3. The NDM-capped Ag2S nanoparticles are synthesized in the microemulsion, the size of the spherical particles is about 53nm. FTIR spectra indicate that the Ag2S nanoparticles are capped by the NDM and the particles become hydrophobic. The NDM-capped Ag2S nanoparticles monolayer is prepared successfully by spreading the particles onto the water. The particles arrange more orderly in monolayer with the increase of surface pressure. In addition, the multiplayer film containing surfactant-capped Ag2S nanoparticles has been fabricated by the Langmuir-Blodgett technique. The Uv spectra show that the LB film has notable quantum-size domino-offect.4. AgxCdyS nanoparticles are obtained beneath arachidic acid monolayer, floating on aqueous solution containing Ag+ and Cd2+, by inputting H2S over the monolayer. The arachidic acid/ AgxCdyS LB films are prepared by transferring their monolayer onto substrate. The small angle X-ray diffraction identified obvious period structure of the LB films. The molar ratio of Ag and Cd in AgxCdyS is 0.16:0.84, measured bythe XPS. The formation mechanism of the AgxCdyS nanoparticles induced and controlled by the headgroups of arachidic acid in the monolayer in terms of lattice matching was discussed.更多还原