Impact on Morphological Characterization and Emulsion Stability of Lactoferrin–Beet Pectin Electrostatic Complexes

Interfacial protein–polysaccharide complexes can be utilized in emulsion-based delivery system and contained functional component or medical ingredient. In the present work, the interaction of lactoferrin (LF, 0.2 wt%) with beet pectin (BP, 0–0.15 wt%) was researched in aqueous solutions at different pH (2–9) and ionic strength (0–800 mM) to provide the information about properties of complexes. A simulative environment was created to explore the optimal concentration of BP to formulate LF-coated stabilized emulsion and how the emulsion responded to the changing environmental pH (2–9) and ionic strength (0–500 mM). Particle size, particle distribution index, zeta-potential, turbidity, Turbiscan stability index,, and peak thickness were used to characterize the physical stability of emulsions. The confocal laser scanning microscopy was used to derive the microscopy images of droplets. The results indicated that 0.4 wt% was the optimal concentration to formulate emulsions, and the LF-BP-coated bilayer emulsion has a preferable stability in more extensive range than the pure LF-stabilized emulsions under the environmental stresses through electrostatic interactions. The results of this study will play an important role in facilitating the utilization of LF-BP complexes as an emulsifier in the development of incorporating functional component or medical ingredient into commercial products.     

Formation of ring calcium oxalate patterns induced by domains in DPPC Langmuir-Blodgett films

The ring patterns of calcium oxalate crystals were induced by domains in Langmuir-Blodgett （LB） films of dipalmitoylpho- sphatidylcboline （DPPC）. The result was explained by the defects at the ring boundaries of liquid condensed （LC） and liquid expanded （LE） phases of LB film. These boundaries could provide less free energy and much more nucleating sites for COM crystals.     

胆酸钠与支撑磷脂双层膜作用的电化学研究

采用电化学方法研究胆酸钠(NaC)与s-BLM的相互作用, 并结合实验结果对NaC与s-BLM的作用机理进行了讨论.     

羟自由基对支撑磷脂双层膜的破坏及水溶性抗氧化剂保护作用的电化学研究

以支撑磷脂双层膜(supported bilayer lipid membrane, s-BLM)作为生物膜模型, 利用Fenton体系产生羟自由基(hydroxyl free radical, •OH), 采用循环伏安法研究了s-BLM与•OH之间的相互作用. 结果表明: •OH通过与磷脂发生化学反应, 诱发s-BLM上形成孔洞或缺陷, 这种作用对时间、FeSO₄和H₂O₂的浓度具有依赖性, 且不可恢复. 具有还原性基团的抗氧化剂维生素C, 还原型谷胱甘肽和L-半胱氨酸, 通过与•OH发生氧化还原反应, 可抑制•OH与s-BLM的相互作用, 降低•OH对s-BLM结构的破坏程度.     

Solvothermal Synthesis and Crystal Structure of a Layered Thioantimonate(Ⅲ) [C4H9NH3]2Sb4S7

An inorganic-organic hybrid thioantimonate(Ⅲ) [CH3(CH2)3NH3]2Sb4S7 1 with layered structure was synthesized by solvothermal method.1 crystallizes in the triclinic system, space group P with a = 7.0124(11), b = 11.919(2), c = 14.879(3) (A), α = 108.791(3), β = 102.441(3), γ = 92.846(2)o, V = 1140.1(3) (A)3, Mr = 859.71, Z = 2, Dc = 2.504 g/cm3, μ= 5.324 mm-1, F(000) = 804, S = 1.013, the final R = 0.0297 and wR = 0.0618 for 3534 observed reflections with I＞2σ(I). 1 consists of [C4H9NH3] cations and two-dimensional [Sb4S7]n2n-anion which is composed of three SbS3 trigonal pyramids and one SbS4 unit joined by sharing common corners. The anionic layers are stacked perpendicularly to the c axis of the unit cell forming two-dimensional channels between the layers. The [C4H9NH3] cations interdigitate in a bilayer and reside in the 2D channels leading to a sandwich-like arrangement of the anion and cations.     

囊泡表面分子间通讯交流体系的构建: 利用受体的分子识别行为调控酶的活性

在人工双层膜囊泡表面, 构建了一个通过人工受体的分子识别行为控制酶反应活性的超分子体系. 体系以生物体细胞信号转导系统为模拟原型, 由作为受体的烷基胺、被受体识别的信号分子吡哆醛衍生物、乳酸脱氢酶、受体和酶之间的媒介物Cu^2＋以及作为体系载体的合成肽脂囊泡五个成分构成．通过UV-vis光谱法及动态光散射测定对体系进行了评价, 结果表明: 随着受体疏水参数增大, 其对信号分子的识别能力增强, 二者呈良好的线性关系; 通过信号分子与囊泡表面静电相互作用的研究表明信号分子具有选择性; 媒介物与信号分子–受体可形成化学计量比为1∶2的配合物, 其形成能力比媒介物与酶的结合能力更强．作为结论, 体系中烷基胺受体对磷酸吡哆醛信号分子的识别有效控制了处于囊泡表面的乳酸脱氢酶的活性．     

荧光性自组装双层膜的制备及其性能研究

借助Au-S化学键的作用,在金基底上组装DL-半胱氨酸,利用DL-半胱氨酸与1-萘胺乙酸(NAA)的静电吸引作用在金表面间接组装荧光试剂NAA,从而构建了双层自组装膜NAA/Cys/Au.该自组装膜有较强的荧光信号,能被Cu²⁺猝灭,并具有较好的可逆再生性能,可用于超痕量铜离子的界面荧光测定,对Cu²⁺的检出下限为7.87×10^-11mol/L.同时采用电化学、荧光光谱及电子能谱等方法表征自组装膜的结构,并采用电化学阻抗谱技术和循环伏安法研究自组装膜在K₃[Fe(CN)₆]/K₄[Fe(CN)₆]溶液中的电化学行为研究.结果表明,金表面组装的单层膜具有良好的“针孔”效应,组装上荧光试剂之后形成的无“针孔”缺陷的自组装双层膜对溶液与基底间的界面电子转移有强烈的阻碍作用.     

Assessing the Apparent Effective Thickness of the Supported Hybrid Bilayer Membranes Consisting of Octadecanethiol and Phospholipid by ac Impedance Spectroscopy

The electrochemical behavior of the gold electrode modified by hybrid bilayer membranes in different concentrations of Fe(CN)₆^3?/Fe(CN)₆^4? was investigated by electrochemical impedance spectroscopy and cyclic voltammetry technology. The electron transfer between gold and the redox species separated by the hybrid bilayers assembly was completed by an electron tunneling process. A detailed equivalent circuit for electron transport across the HBMs is proposed. It was found that the apparent effective thickness of the hybrid bilayer membranes was lower than that of the sum of the chain length of octadecanethiol and phospholipid so some possible collapsed sites might exist at the hybrid bilayer membranes.     

Uncompensated magnetization and exchange-bias field in La0.7Sr0.3MnO3/YMnO3 bilayers: The influence of the ferromagnetic layer

We studied the magnetic behavior of bilayers of multiferroic and nominally antiferromagnetic o-YMnO₃ (375 nm thick) and ferromagnetic La_0.7Sr_0.3MnO₃ and La_0.67Ca_0.33MnO₃ (8…225 nm), in particular the vertical magnetization shift M_E and exchange-bias field H_E for different thickness and magnetic dilutions of the ferromagnetic layer at different temperatures and cooling fields. We have found very large M_E shifts equivalent to up to 100% of the saturation value of the o-YMO layer alone. The overall behavior, including XMCD magnetization shift measured at the Mn-L edge of the LSMO layer only, indicates that the properties of the ferromagnetic layer contribute substantially to the M_E shift and that this does not correlate straightforwardly with the measured exchange-bias field H_E.     

The Impact of an Anchoring Layer on the Formation of Tethered Bilayer Lipid Membranes on Silver Substrates

Tethered bilayer lipid membranes (tBLMs) have been known as stable and versatile experimental platforms for protein–membrane interaction studies. In this work, the assembly of functional tBLMs on silver substrates and the effect of the molecular chain-length of backfiller molecules on their properties were investigated. The following backfillers 3-mercapto-1-propanol (3M1P), 4-mercapto-1-butanol (4M1B), 6-mercapto-1-hexanol (6M1H), and 9-mercapto-1-nonanol (9M1N) mixed with the molecular anchor WC14 (20-tetradecyloxy-3,6,9,12,15,18,22 heptaoxahexatricontane-1-thiol) were used to form self-assembled monolayers (SAMs) on silver, which influenced a fusion of multilamellar vesicles and the formation of tBLMs. Spectroscopic analysis by SERS and RAIRS has shown that by using different-length backfiller molecules, it is possible to control WC14 anchor molecules orientation on the surface. An introduction of increasingly longer surface backfillers in the mixed SAM may be related to the increasing SAMs molecular order and more vertical orientation of WC14 at both the hydrophilic ethylenoxide segment and the hydrophobic lipid bilayer anchoring alkane chains. Since no clustering of WC14 alkane chains, which is deleterious for tBLM integrity, was observed on dry samples, the suitability of mixed-component SAMs for subsequent tBLM formation was further interrogated by electrochemical impedance spectroscopy (EIS). EIS showed the arrangement of well-insulating tBLMs if 3M1P was used as a backfiller. An increase in the length of the backfiller led to increased defectiveness of tBLMs. Despite variable defectiveness, all tBLMs responded to the pore-forming cholesterol-dependent cytolysin, vaginolysin in a manner consistent with the functional reconstitution of the toxin into phospholipid bilayer. This experiment demonstrates the biological relevance of tBLMs assembled on silver surfaces and indicates their utility as biosensing elements for the detection of pore-forming toxins in liquid samples.