锚定的磷脂双层膜的制备及其形貌结构

利用表面硅烷化方法对化学氧化的单晶硅表面进行修饰,成功地将抗生物素蛋白固定在表面上,并且用囊泡融合法成功得到了大面积、连续的磷脂双层膜。由于成功地在基底与磷脂膜间引入了5nm左右的水层,原子力显微镜观察表明这种锚定的磷脂双层膜(tethered bilayer lipid membrane, tBLM)表现出与磷脂支持膜不同的相形为。两种膜相形为的不同可以用磷脂分子与基底间相互作用的不同来解释。     

多孔硅中金属钯的电沉积与表征

采用电沉积法对自制大深径比盲孔(直径7.7~7.8μm,深度78μm)多孔硅进行金属钯填充。镀液组成和工艺条件为:PdCl2 8.8 g/L,KCl 15.0 g/L,NH3·H2O 50 mL/L,乙醇和水各50%(体积分数),pH 8~9,电压15 V,电流1.5 mA,惰性气体搅拌,时间17 h。采用扫描电镜和能谱仪分析了钯在多孔硅中的填充情况。结果表明,金属钯在多孔硅盲孔中实现了满载填充,并在孔的外表面也有沉积。本工艺镀液组成简单,为制备三维硅基氚电池提供了技术基础。     

化学腐蚀法制备纳米多孔硅及其表面形貌表征

采用化学腐蚀法制备了纳米多孔硅粉.利用扫描电子显微镜对多孔硅粉的表面形貌进行了表征.结果表明,在HNO3浓度、反应时间和HNO3滴加时间3种因素中,HNO3浓度对硅粉的腐蚀效果影响最大;浓度过高或者较低时,均不能获得良好的硅粉形貌.HNO3质量分数以20％～25％为宜.反应时间对硅粉结构和形貌的影响比硝酸的滴加速率大.在较低HNO3浓度条件下,延长反应时间对硅粉进行腐蚀更为有效.     

多孔硅的形貌、制备和应用

介绍了近年来制备多孔硅的主要方法,以及多孔硅在光电传感器、发光器件、电池、生物技术等新领域的应用。     

硅基底自组装双层膜制备与摩擦磨损性能研究

用自组装方法在羟基化硅基底表面制备十八胺／环氧硅烷双层膜,采用接触角测定仪、椭圆偏光仪、红外光谱仪、原子力显微镜、X射线光电子能谱（XPS）和UMT-2MT型摩擦试验机,评价了薄膜结构和摩擦磨损特性。结果表明：自组装双层膜对水的接触角为100°,膜厚3．2nm,双层膜中烷基链呈现较好的有序性;其表面均方根粗糙度为0．241nm;分子内存在C—N化学键,分子间存在氢键;十八胺／环氧硅烷自组装双层膜能够有效把基底的摩擦系数从0．6降低到0．08,0．5N载荷下,摩擦系数随速度增加而增加,在0．5N、1．5N和3N载荷下,耐磨寿命分别为17800个循环以上,2400个循环和1600个循环,呈现良好的耐磨性。     

用STM研究电化学阳极氧化制备的多孔硅

本文利用扫描隧道显微镜（ＳＴＭ）并辅以快速富立叶变换（ＦＦＴ）和数据拟合等数学方法对电化学极氧化法制备的多孔硅（ＰＳ）的微结构及形貌进行了研究。同时研究了多孔硅的微结构与其发生性质和电化学性质的相互关系。研究表明，在其他条件不变情况下，随阳极氧化电流密度的增大，所形成的多孔硅的微孔向纵深延伸，多孔硅层增厚，微孔相连后形成的硅柱变细，发光强度增大，发光峰位明显蓝移，与单晶硅相比，多孔硅电极的平带电位     

镁热还原法制备多孔硅碳复合负极材料

分别以介孔二氧化硅(SBA-15和 MCM-48)和硅藻土为硅源,通过镁热还原制备多孔硅,然后向多孔硅中注入有机碳前躯体,经过高温碳化处理得到多孔Si/C复合负极材料。采用X射线衍射仪、Raman光谱仪、场发射扫描电子显微镜和N2吸附脱附测试仪对合成的材料分别进行了表征,研究了多孔 Si/C 复合材料的电化学性能。结果表明：镁热还原介孔二氧化硅可以得到多孔硅材料,碳加入到多孔硅材料中可以有效提高材料的电子电导率,可明显改善材料的循环稳定性。同时多孔结构可以有效缓解硅基材料充放电过程中的体积应力,提高材料的循环稳定性。以SBA-15、MCM-48和硅藻土为硅源制备得到的3种多孔Si/C复合材料在200 mA/g电流密度下循环30次之后的可逆容量分别为712、664、463 mA·h/g。     

多孔氧化铝支撑体的制备与表征

以α-Al2O3粉末为骨料,采用塑性挤压成型技术和固态粒子烧结法制备Al2O3多孔陶瓷支撑体。研究了粘结剂和成孔剂的种类对支撑体性能的影响。研究结果表明:通过选用合适的粘结剂和成孔剂,可制得孔径分布窄、孔隙率高的支撑体。     

光伏硅线切割固体废料制备多孔SiC陶瓷

以光伏硅线切割固体废料为主要原料,外加胶体石墨粉和碳化硅粉采用固相烧结法制备SiC多孔陶瓷。研究了烧成制度、石墨的加入量等对SiC多孔陶瓷性能的影响。结果表明:采用炭黑埋烧工艺可得到性能较好的多孔SiC陶瓷。在1400℃时,切割回收废料直接炭黑填埋烧制,试样的体积密度为1.65g/cm3,吸水率为26.92%,显气孔率43.96%;在1600℃时,当配方中加入石墨,使得Si和C的摩尔比为1∶6时,试样的吸水率为15.65%,体积密度为1.84g/cm3,显气孔率为38.25%。     

采用石墨电极制备多孔硅工艺研究

采用石墨电极作为阴极,通过向腐蚀溶液中添加适量65％(质量分数wt％,下同)浓硝酸,以电化学腐蚀法在单晶硅片表面制备出多孔硅微结构.实验表明,随着腐蚀时间的增加,衡量多孔硅表面形貌的粗糙度和颗粒度指标值呈周期性增减变化;在电流密度为10 mA/cm2的阳极腐蚀参数下,将单晶硅片腐蚀1875秒制备的多孔硅样品的粗糙度和颗粒度值相对较大,原子力显微镜(AFM)和扫描电子显微镜(SEM)检测结果表明其硅柱最大高度、颗粒最大直径和平均直径分别达到470 nm、1693.590nm、489.954nm.     

Preparation of DOPC and DPPC Supported Planar Lipid Bilayers for Atomic Force Microscopy and Atomic Force Spectroscopy

Cell membranes are typically very complex, consisting of a multitude of different lipids and proteins. Supported lipid bilayers are widely used as model systems to study biological membranes. Atomic force microscopy and force spectroscopy techniques are nanoscale methods that are successfully used to study supported lipid bilayers. These methods, especially force spectroscopy, require the reliable preparation of supported lipid bilayers with extended coverage. The unreliability and a lack of a complete understanding of the vesicle fusion process though have held back progress in this promising field. We document here robust protocols for the formation of fluid phase DOPC and gel phase DPPC bilayers on mica. Insights into the most crucial experimental parameters and a comparison between DOPC and DPPC preparation are presented. Finally, we demonstrate force spectroscopy measurements on DOPC surfaces and measure rupture forces and bilayer depths that agree well with X-ray diffraction data. We also believe our approach to decomposing the force-distance curves into depth sub-components provides a more reliable method for characterising the depth of fluid phase lipid bilayers, particularly in comparison with typical image analysis approaches.     

多孔N-乙酰化壳聚糖超滤膜的制备及表征

以相转化法制备了N-乙酰化壳聚糖超滤膜,探讨了不同的致孔剂和蒸发条件对膜孔结构的影响,并用扫描电镜对其表面形貌进行了分析,并对膜的机械性能和对染料溶液酸性红B的分离性能进行了考察。分析结果表明:以乙醇为致孔剂、红外蒸发干燥10min制备的多孔壳聚糖膜孔径均匀,孔隙率高;膜的机械性能好,膜在干、湿态下的最大抗张强度分别达到445.4Kg/m2和182.4Kg/m2;膜的分离性能好,渗透通量达到2.1ml/cm2.h,截留率达到96.3%。     

硅锆复合膜的制备与表征

以硝酸锆为前驱体,二氧化硅为晶型稳定剂,采用溶胶-凝胶法在多孔氧化铝载体上制备了无缺陷的硅锆复合膜.借助TG-DTA、XRD、BET、SEM、TEM和AFM等测试手段对膜的表面形貌、孔径分布以及热稳定性进行了分种析和表征.实验结果表明,硝酸锆比氧氯化锆更适合作前驱体,可获得均匀分布的稳定溶胶;当二氧化硅含量为25%(摩尔百分数)时,可以得到平整无缺陷的硅锆复合膜;焙烧过程中,不同升温区间须采用不同的升温速率,以防止膜的开裂;由于二氧化硅与氧化锆间的相互作用,抑制了氧化锆晶型的转变,同时也提高了二氧化硅的晶化温度.硅锆复合膜在700～900℃范围内保持单一的氧化锆四方晶型,晶粒大小几乎不随温度变化,具有良好的热稳定.     

Engineering Lipid Bilayer Membranes for Protein Studies

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques.     

SPG膜乳化与界面聚合法制备单分散多孔微囊膜

小粒径单分散中空储库结构微囊膜的制备具有重要学术意义和实用价值。为此采用了SPG(Shirasu-Porous-Glass)膜乳化法和界面聚合法，对小粒径单分散多孔微囊膜的制备进行了较系统的实验研究，以期为进一步制备多孔内接枝环境感应型功能凝胶开关的小粒径单分散微囊型靶向式药物载体提供基体。研究结果表明，采用SPG膜乳化法可制得单分散性良好的乳液液滴，进而采用界面聚合法可得到单分散微囊。用膜乳化方法易于控制乳液液滴及微囊的大小，在研究中SPG膜乳化法制备的乳液液滴及微囊的平均粒径大约是所用膜孔径的3．6倍。微囊膜的多孔性可以靠改变溶剂和单体的成分来进行控制，扫描电镜检测结果表明所制备出的不同粒径级别的单分散微囊膜均具有良好的多孔结构。     

AFM and Multiple Transmission-Reflection Infrared Spectroscopy (MTR-IR) Studies on Formation of Air-Stable Supported Lipid Bilayers

Supported lipid bilayers (SLBs) were prepared by deposition of unilamellar vesicles on a silicon substrate. Atomic force microscopy (AFM) and a new Multiple Transmission-Reflection Infrared Spectroscopy (MTR-IR) developed by us were used to trace the dynamic formation of lipid bilayers on the silicon surfaces. The evolution from deformation of vesicles to formation of bilayers can be distinguished clearly by AFM imaging. MTR-IR provided high quality infrared spectra of ultrathin lipid bilayers with high sensitivity and high signal to noise ratio (SNR). The structural and orientational changes during vesicle’s fusion were monitored with MTR-IR. MTR-IR shows superiority over other infrared approaches for ultrathin films on standard silicon wafers in view of its economy and high sensitivity. Both MTR-IR and AFM results were consistent with each other and they provided more information for understanding the self-assembling procedure of SLBs.     

加压和超临界流体在多孔膜中的渗透

考察加压和超临界流体在多孔膜中渗透过程的各种影响因素并进行模型分析,对深入认识过程的传质机理、开发普遍适用的数学模型有重要意义。首先实验测定了不同温度、压力和压差条件下,He、N2和CO2在多孔陶瓷膜中的渗透率,考察了各主要影响因素。以二项尘气模型为基础,考虑到流体枯度随压力的变化,特别是近临界区流体枯度可能出现的突变,对模型进行了修正,建立了新的模型表达式。理论分析与实验结果表明,加压和超临界条件下,由于He的粘度变化甚微,其渗透过程仍然符合二项尘气模型,而对于N2需要考虑粘度随压力变化对渗透率计算结果的影响。由于近临界区相交的作用,CO2在多孔膜中的渗透过程出现奇异现象;而在低压和高压条件下,本研究建立的渗透模型与实验结果十分吻合。     

Trichogin GA IV Alignment and Oligomerization in Phospholipid Bilayers

Trichogin GA IV is a short peptaibol with antimicrobial activity. This uncharged, but amphipathic, sequence is aligned at the membrane interface and undergoes a transition to an aggregated state that inserts more deeply into the membrane, an assembly that predominates at a peptide-to-lipid ratio (P/L) of 1:20. In this work, the natural trichogin sequence was prepared and reconstituted into oriented lipid bilayers. The ¹⁵N NMR chemical shift is indicative of a well-defined alignment of the peptide parallel to the membrane surface at P/Ls of 1:120 and 1:20. When the P/L is increased to 1:8, an additional peptide topology is observed that is indicative of a heterogeneous orientation, with helix alignments ranging from around the magic angle to perfectly in-plane. The topological preference of the trichogin helix for an orientation parallel to the membrane surface was confirmed by attenuated total reflection FTIR spectroscopy. Furthermore, ¹⁹F CODEX experiments were performed on a trichogin sequence with ¹⁹F-Phe at position 10. The CODEX decay is in agreement with a tetrameric complex, in which the ¹⁹F sites are about 9–9.5 Å apart. Thus, a model emerges in which the monomeric peptide aligns along the membrane surface. When the peptide concentration increases, first dimeric and then tetrameric assemblies form, made up from helices oriented predominantly parallel to the membrane surface. The formation of these aggregates correlates with the release of vesicle contents including relatively large molecules.     

以多孔金属钛片为载体的SiO2膜的制备和表征

采用溶胶－凝胶法，用正硅酸乙酯为原料，以多孔金属钛片为载体，制备了担载型多孔ＳｉＯ２复合膜。探讨了制备过程参数对膜性能的影响。建立了基于Ｋｅｌｖｉｎ方程，以流动法测定了无机微孔膜的活性孔径分布的装置，检测了膜的活性孔孔径分布。     

Functional Investigations of Thromboxane Synthase (CYP5A1) in Lipid Bilayers of Nanodiscs

CYP5A1 is a membrane‐associated cytochrome P450 that metabolizes the cyclooxygenase product prostaglandin (PGH₂) into thromboxane A₂ (TXA₂), a potent inducer of vasoconstriction and platelet aggregation. Although CYP5A1 is an ER‐bound protein, the role of membranes in modulating the thermodynamics and kinetics of substrate binding to this protein has not been elucidated. In this work, we incorporated thromboxane synthase into lipid bilayers of nanodiscs for functional studies. We measured the redox potential of CYP5A1 in nanodiscs and showed that the redox potential is within a similar range of other drug‐metabolizing P450 enzymes in membranes. Further, we showed that binding of substrate to CYP5A1 can induce conformational changes in the protein that block small‐molecule ligand egress by measuring the kinetics of cyanide binding to CYP5A1 as a function of substrate concentration. Notably, we observed that sensitivity to cyanide binding was different for two substrate analogues, U44069 and U46619, thus indicating that they bind differently to the active site of CYP5A1. We also characterized the effects of the different lipids on CYP5A1 catalytic activity by using nanodiscs to create unary, binary, and ternary lipid systems. CYP5A1 activity increased dramatically in the presence of charged lipids POPS and POPE, as compared to the unary POPC system. These results suggest the importance of lipid composition on modulating the activity of CYP5A1 to increase thromboxane formation.