LB膜诱导下草酸钙晶体的生物矿化研究

草酸钙（CaC２O４）结石是生物体内异常矿化形成的产物，是泌尿系结石的主要组成部分犤１犦。它形成于泌尿系统中尿路表皮细胞上犤２犦。磷脂的Langmuir－Blodgett（LB）膜是生物细胞膜的简化模拟体系犤３犦。用磷脂LB膜作为模板来研究CaC２O４晶体的形成过程，比在水溶液中更能接近CaC２O４结石在生物体内细胞膜表面形成的真实情况，将有助于对尿路结石的形成及防治的研究犤４犦。尿大分子硫酸软骨素A（C４S）存在于尿液中，但不存在于CaC２O４结石中。在结石病人尿液中C４S的含量明显低于正常人尿液中的含量，因此推测其在体内…     

LB膜中的缺陷畴区及其诱导形成环形草酸钙图形

利用存在缺陷的LB膜来模拟受损伤的肾上皮细胞膜诱导肾结石矿物草酸钙(CaOxa)晶体生长. 经2.5 mmol·L-1的草酸钾溶液对二棕榈酰磷脂酰胆碱(DPPC)的LB膜进行处理后, 可强化LB膜中液态扩张相(LE)和液态凝聚相(LC)之间的结构差异, 原子力显微镜(AFM)证实了圈状缺陷的存在. 以LB膜的圈状缺陷为模板, 诱导了一水草酸钙(COM)晶体环状图案. 相比之下, 未经草酸钾处理的LB膜只诱导生成零散的六边形COM晶体.     

LB膜诱导CaF2单晶的生长研究

LB膜作为模板可调控晶体的取向生长。实验中利用SEM，XRD等手段研究转移到硅基底上的LB膜诱导氟化钙单晶的生长情况。发现：在二十二烷基羧酸LB诱导下，氟化钙晶体沿（220）晶面取向生长，这一结果可利用膜与晶体之间的晶格匹配关系得到合理解释。     

"液晶"调控的磷酸钙盐矿化材料的研究

双亲分子在适当的条件下能形成LB膜或自组装成各种形状、结构的聚积体,可以作为生物模拟材料的“模板”,它能严格精巧的参与调控模拟材料的尺子、形貌以及晶体的取向[1-5,7]。如具有纳米微结构磷酸锌分子筛、二氧化硅沸石和被四氧化三铁包被的磁性微管等等。Com inic walsh应用     

小分子盐对盐酸十八胺单层膜影响的研究

利用Langmuir单层膜模拟生物矿化过程或者是利用LB膜技术构筑层状固体模板来制备与组装纳米材料已成为新的研究热点~([1,2]),因为通过变换成膜材料及制备条件,可以调控生成材料的性质.Langmuir单分子膜的成膜性能直接决定着LB膜的沉积质量、结构和性能~([3,4]).     

草酸钾诱导的LB膜缺陷及对草酸钙堆积图形的影响

采用扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了经不同浓度草酸钾(K2C2O4)处理后二棕榈酰磷酯酰胆碱(DPPC)的缺陷LB膜及其对一水草酸钙(COM)成核和生长的影响. K2C2O4的处理可进一步破坏LB膜中圆形畴区内的分子列阵, 尤其是使处在液态扩张相(LE)/液态凝集相(LC)边界的分子列阵无序程度增加, 从而促进了COM晶体在此处的成核和生长, 最终诱导圆形堆积的COM晶体图形出现. 随着损伤LB膜的K2C2O4浓度c(K2C2O4)从0.3 mmol/L增加到5.0 mmol/L, 其对LB膜畴区有序结构的破坏作用逐渐增强, 圈状堆积的晶体图形数量增多. 当c(K2C2O4)为0.3 mmol/L时, 主要诱导实心的圆形堆积的COM晶体图形, 而当c(K2C2O4)增加至5.0 mmol/L时, 生成圈状COM晶体图形, 且图形的半径减小. 这一研究结果将有助于从分子和超分子水平上了解肾小管上皮细胞膜损伤后的微结构变化及其与肾结石形成的关系.     

缺陷LB膜诱导草酸钙晶体环图形形成

利用存在缺陷的LB膜来模拟受损伤的肾上皮细胞膜, 研究了膜缺陷的微结构及其影响一水草酸钙(COM)晶体成核、生长、沉积图形和黏附的分子机制. 二棕榈酰磷脂酰胆碱(DPPC)LB膜经草酸钾处理后可形成圆形缺陷, 并诱导COM微晶排列成环状图形, 相比之下, 没有经草酸钾处理的LB膜只诱导零散的六边形COM晶体生成. 随着生长时间增加, 环内单个COM晶体的尺寸明显增加, 空心的环状晶体图形倾向于转变为实心的圆形图形, 且小尺寸(5~20 mm)的圆形晶体图案数量增加. 本结果有助于在分子和超分子的水平上进一步了解肾上皮细胞膜损伤后诱导肾结石形成的分子机制.     

水玻璃为原料在开放体系中快速合成介孔材料MCM-41

自从 M41 S系列硅基介孔分子筛被人工合成以来[1,2 ] ,有关分子筛的合成、性能、形成机理、结构和应用等方面的研究报道不断出现[3～ 5] .目前 ,由有机 -无机离子经分子水平的自组装结合而产生介孔材料的合成机理主要归结于在合成过程中表面活性剂的模板效应 ,如液晶模板机理[1,2 ] 、棒状自组装模型[6 ] 、电荷匹配机理[7] 、层状折皱模型[8] 和使用非离子表面活性剂合成介孔材料等效应[9] .本文以水玻璃作为硅源 ,以十六烷基三甲基溴化铵 (CTAB)阳离子表面活性剂为模板剂 ,在温和条件下 ,采用开放体系合成出具有 MCM-4 1结构特点的介…     

乙基纤维素粘度对甲基膦酸二甲酯检测的影响

石英晶体微天平(QCM)作为一种质量敏感型传感器已广泛用于气体检测、气体成分分析、环境监测、免疫分析、军事化学等领域[1],其原理是依靠晶体表面涂覆的膜材料吸附气体的量所引起的频率变化来实现的,因而其性能很大程度上取决于膜材料的特性.乙基纤维素已用于化学战剂及其模拟剂的检测[2-3],但尚未见有文献对其粘度影响进行具体研究.本文在前期工作基础上[3],详细研究了不同粘度的乙基纤维素作为QCM膜材料对甲基膦酸二甲酯(DMMP)检测的影响,为传感器及膜材料在军事化学中的应用提供了方法和依据.     

新型含磷酰基的脂溶性自由基捕捉剂的合成及其ESR研究

超氧阴离子自由基的研究最近得到了广泛的关注 ,这主要是因为超氧阴离子自由基及由其诱导产生的各种活性氧 ( HOO· ,HO· 和 H2 O2 )与许多病理过程有关 ,如发炎 [1] 、缺血再灌综合症 [2 ] 、 DNA损伤[3] 和神经死亡疾病 [4 ] 等 .自旋捕捉技术是检测自由基最有效的方法 [5～ 9] ,近年来在生物体系活性氧自由基检测中得到广泛应用 [10 ,11] ,大力推动了生物自由基领域的研究 .合成新型自由基捕捉剂及改善其对超氧阴离子自由基的捕捉性能一直是人们追逐的热点 ,我们正致力于这方面的研究 [12 ] .其中提高自由基捕捉剂的脂溶性 ,扩大自…     

单分子膜诱导下尿大分子对草酸钙晶体物相和晶面的调控作用

采用SEM,XRD和FTIR手段比较研究了DPPC单分子膜诱导下尿大分子硫酸软骨素A(C₄S)、硫酸软骨素C(C₆S)和血清蛋白(SA)对尿石盐草酸钙晶体生长的影响.DPPC单分子膜不但优先选择一水草酸钙(COM)物相成核生长,而且优先选择COM的(101)晶面.没有添加剂时,得到的COM为三维的六棱柱和三维的菱形晶体;加入尿大分子抑制剂后,COM的(101)晶面进一步加强,其它晶面减弱,导致二维晶体的形成.COM的(101)晶面为富钙离子晶面,带有过剩的正电荷,而DPPC单分子膜头基带有负电荷,几种尿大分子在实验条件下亦带有负电荷,带负电荷的单分子膜及带负电荷的大分子共同作用于富钙离子的(101)晶面,使得COM的(101)晶面择优生长.C₄S,C₆S和SA的存在均能有效地抑制COM生长.     

Molar mass dependent growth of poly(epsilon-caprolactone) crystals in Langmuir films

Poly(epsilon-caprolactone) (PCL) samples with number average molar masses (Mn) ranging from 3.5 to 36 kg.mol-1 exhibit molar mass dependent nucleation and growth of crystals, crystal morphologies, and melting properties at a temperature of 22.5 degrees C in Langmuir films at the air/water (A/W) interface. At surface area per monomer, A, greater than approximately 0.37 nm2.monomer-1, surface pressure, Pi, and surface elasticity exhibit molar mass independent behavior that is consistent with a semidilute PCL monolayer. In this regime, the scaling exponent indicates that the A/W interface is a good solvent for the liquid-expanded PCL monolayers. Pi-A isotherms show molar mass dependent behavior in the vicinity of the collapse transition, i.e., the supersaturated monolayer state, corresponding to the onset of the nucleation of crystals. Molar mass dependent morphological features for PCL crystals and their subsequent crystal melting are studied by in situ Brewster angle microscopy during hysteresis experiments. The competition between lower segmental mobility and a greater degree of undercooling with increasing molar mass produces a maximum average growth rate at intermediate molar mass. This behavior is analogous to spherulitic growth in bulk PCL melts. The plateau regions in the expansion isotherms represent the melting process, where the polymer chains continuously return to the monolayer state. The magnitude of Pi for the plateau during expansion decreases with increasing molar mass, indicating that the melting process is strongly molar mass dependent.     

Growth and characterization of unidirectional (100) KDP single crystal by Sankaranarayanan-Ramasamy (SR) method

Unidirectional (100) potassium dihydrogen orthophosphate (KDP) single crystals were grown by Sankaranarayanan-Ramasamy (SR) method. The (100) oriented seed crystals were mounted at the bottom of the glass ampoules and the crystals of 20mm diameter, 30 mm height and 15 mm diameter, 65 mm height were grown by SR method. The grown crystals were characterized by high-resolution X-ray diffractometry anlaysis, UV-vis spectroscopy, dielectric and microhardness studies. The high-resolution X-ray diffractometry anlaysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. The SR method-grown unidirectional KDP has 15% higher transmittance compared to conventional method-grown crystals. The dielectric constant was higher and the dielectric loss was less in SR method-grown crystal. The crystals grown by SR method have much higher hardness value than conventional method-grown crystals. The quality of the crystal grown by SR method is better than conventional method-grown crystal.     

Brewster angle microscopy of calcium oxalate monohydrate precipitation at phospholipid monolayer phase boundaries

The precipitation of calcium oxalate monohydrate (COM) at phospholipid monolayers confined to the air/water interface is observed in situ with the aid of Brewster angle microscopy. COM crystals appear as bright objects that are easily identified and quantified to assess the effects of different conditions on crystallization. Crystal precipitation was monitored at monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in liquid condensed (LC) and liquid expanded (LE) phases. Within the LC phase, higher pressures reduce the incidence of crystallization at the interface, implying that within this phase precipitation is enhanced by higher compressibility or fluidity of the monolayer. Precipitation at biphasic LC/LE and LE/gas (G) monolayers was also studied. COM appears preferentially at phase boundaries of the DPPC LC/LE and LE/G monolayers. However, when an LC/LE phase boundary is created by two different phospholipids that are phase segregated, such as DPPC and 1,2-dimyristoyl-sn-glycero-3-phosphocholine, crystal formation occurs away from the interface within the DPPC LC phase. It is suggested that COM growth at phase boundaries is preferred only when there is molecular exchange between the phases.     

Growth, structural, optical and thermal properties of gamma-glycine crystal

Single crystals of gamma-glycine were grown from a mixture of glycine, water and lithium bromide. Single crystal X-ray diffraction analysis confirmed the growth of gamma-glycine phase. Presence of various functional groups of gamma-glycine was identified by FTIR spectrum. Optical absorbance spectrum recorded in the wavelength range of UV-vis-NIR revealed that this crystal has good optical transparency in the range 250-1500 nm. Vickers microhardness values were estimated on the prominent (100) face. Thermogravimetric and differential scanning calorimetric analyses were carried out to study the thermal properties of gamma-glycine. Second harmonic generation efficiency of the crystal measured by Kurtz's powder method using Nd:YAG laser is about three times that of KDP.     

Crystal nucleation, growth, and morphology of the synthetic malaria pigment beta-hematin and the effect thereon by quinoline additives: the malaria pigment as a target of various antimalarial drugs

The morphology of micrometer-sized beta-hematin crystals (synthetic malaria pigment) was determined by TEM images and diffraction, and by grazing incidence synchrotron X-ray diffraction at the air-water interface. The needle-like crystals are bounded by sharp {100} and {010} side faces, and capped by {011} and, to a lesser extent, by {001} end faces, in agreement with hemozoin (malaria pigment) crystals. The beta-hematin crystals grown in the presence of 10% chloroquine or quinine took appreciably longer to precipitate and tended to be symmetrically tapered toward both ends of the needle, due to stereoselective additive binding to {001} or {011} ledges. Evidence, but marginal, is presented that additives reduce crystal mosaic domain size along the needle axis, based on X-ray powder diffraction data. Coherent grazing exit X-ray diffraction suggests that the mosaic domains are smaller and less structurally stable than in pure crystals. IR-ATR and Raman spectra indicate molecular based differences due to a modification of surface and bulk propionic acid groups, following additive binding and a molecular rearrangement in the environment of the bulk sites poisoned by occluded quinoline. These results provided incentive to examine computationally whether hemozoin may be a target of antimalarial drugs diethylamino-alkoxyxanthones and artemisinin. A variation in activity of the former as a function of the alkoxy chain length is correlated with computed binding energy to {001} and {011} faces of beta-hematin. A model is proposed for artemisinin activity involving hemozoin nucleation inhibition via artemisinin-beta-hematin adducts bound to the principal crystal faces. Regarding nucleation of hemozoin inside the digestive vacuole of the malaria parasite, nucleation via the vacuole's membranous surface is proposed, based on a reported hemozoin alignment. As a test, a dibehenoyl-phosphatidylcholine monolayer transferred onto OTS-Si wafer nucleated far more beta-hematin crystals, albeit randomly oriented, than a reference OTS-Si.     

Effect of sunset yellow dye on morphological,optical, dielectric,thermal and mechanical properties of KDP crystal

Herein, we describe the growth and morphology of well-defined dyed crystals of KH₂PO₄ (potassium dihydrogen orthophosphate; KDP) containing organic azo (sunset yellow; SSY) dye in the {1 0 1} & {0 0 1} pyramidal growth sectors. An understanding on selective dye inclusion in various growth sector of host crystal is proposed, which will help in designing novel tailor-made dyed photonic crystals. The structural analysis and the identification of various functional groups present in as grown KDP crystals were carried out using powder XRD, FTIR and Raman studies. Solid state transmittance spectra for dyed KDP crystals displayed three absorption peaks at 230 nm, 311 nm and 477 nm, which were blue shifted for SSY dye in KDP crystal relative to neutral aqueous solution of SSY dye. These blue shifts in the absorption maxima confirm the successful incorporation of sunset yellow dye into the pyramidal growth sectors of dyed KDP crystals. The band around 409 nm in the photoluminescence emission spectrum indicates a violet emission. SSY dye doped KDP crystals showed enhanced dielectric properties and thermal stability as compared to pure KDP crystal. The mechanical strength of the KDP crystals estimated using Vickers microhardness test was found to decrease with the increase in SSY dye doping.     

亚相pH值对磷脂单层下甘氨酸结晶过程的影响

亚相pH值对磷脂单层下甘氨酸结晶过程的影响;Langmuir单分子层; 结晶; 取向; 形貌     

Effect of bicarbonate ions on the crystallization of calcite on self-assembled monolayers

We use molecular dynamics simulations to investigate the nucleation of calcite crystals on self-assembled monolayers. We show how the presence of bicarbonate ions adsorbed on the monolayer surface can both aid nucleation and control the orientation of the growth of the crystal. Using a simple model of the nucleation process and calculated interfacial energies, we calculate the enhancement (with respect to the homogeneous nucleation rate) of the nucleation of calcite on the (012) and (0001) faces. The calculations show clearly that the (012) face is favored over the (0001) face and that the nucleation rate is enhanced for self-assembled monolayers made from molecules containing an even number of carbon atoms in the alkyl chain over those containing an odd number.     

Action mechanism of water soluble ethanol on phospholipid monolayers using a quartz crystal oscillator

Interaction between phospholipid monolayers (dihexadecyl phosphate: DHP, dipalmitoyl phosphatidyl choline: DPPC) and water soluble ethanol has been studied using quartz crystal microbalance (QCM) method and quartz crystal impedance (QCI) method. The quartz crystal oscillator was attached horizontally on the DHP and DPPC monolayers that were formed on the water surface. At low concentration, increased ethanol concentration decreased the frequency for QCM and increased the resistance for QCI. Both frequency and resistance approached asymptotically to a saturation value. A further increase in ethanol concentration induced a sudden and discontinuous linear change (a decrease in frequency and an increase in resistance). Based on these results, we propose the following action mechanism of ethanol on phospholipid monolayers: at low concentration, the ethanol hydrates adsorb into the monolayer/water interface and saturate on the interface. The monolayer viscosity also increases with the adsorption of hydrates. A further increase in concentration causes multilayer formation of hydrates and/or penetration of hydrates into the monolayer core. The viscosity of the interfacial layer (monolayer and interfacial structured water) changes dramatically according to the action of ethanol hydrates.