Kinetic and Structural Aspects of Glycosaminoglycan–Monkeypox Virus Protein A29 Interactions Using Surface Plasmon Resonance

Monkeypox virus (MPXV), a member of the Orthopoxvirus genus, has begun to spread into many countries worldwide. While the prevalence of monkeypox in Central and Western Africa is well-known, the recent rise in the number of cases spread through intimate personal contact, particularly in the United States, poses a grave international threat. Previous studies have shown that cell-surface heparan sulfate (HS) is important for vaccinia virus (VACV) infection, particularly the binding of VACV A27, which appears to mediate the binding of virus to cellular HS. Some other glycosaminoglycans (GAGs) also bind to proteins on Orthopoxviruses. In this study, by using surface plasmon resonance, we demonstrated that MPXV A29 protein (a homolog of VACV A27) binds to GAGs including heparin and chondroitin sulfate/dermatan sulfate. The negative charges on GAGs are important for GAG–MPXV A29 interaction. GAG analogs, pentosan polysulfate and mucopolysaccharide polysulfate, show strong inhibition of MPXV A29–heparin interaction. A detailed understanding on the molecular interactions involved in this disease should accelerate the development of therapeutics and drugs for the treatment of MPXV.     

疏水界面上标准蛋白质吸附等温线的研究

测定了几种具有代表性的标准蛋白质在疏水色谱填料上的吸附等温线.除溶菌酶和牛血清白蛋白的吸附近似呈线性外,细胞色素-c、肌红蛋白、胰岛素、α-淀粉酶和卵清蛋白均呈凸型吸附.用Langmuir、计量置换吸附模型(SDM-A)、BET和Jovanovic吸附模型对这些蛋白的吸附等温线拟合后发现,SDM-A关系式能够良好描述这7种蛋白的吸附,Langmuir关系仅能较好地描述后5种蛋白质的吸附.而Jovanovic和BET关系式对上述两类蛋白质吸附的描述欠妥.实验发现对于不同盐浓度条件下卵清蛋白的吸附,用SDM-A和Langmuir公式拟合所得的参数与盐浓度之间呈现出一定的规律性.     

Plasma Treatment of Polymers to Generate Stable,Hydrophobic Surfaces

Tailoring of polymers for multifaceted applications is an increasing field, whereby most often the surface properties must be adjusted. Therefore, the coating of common polymers by plasma polymerization is a promising way to modify the surface and meet the demands. Beside the tuning of the required surface properties, good adhesion and stability of the films is essential. This work investigates the plasma deposition of pp-HMDSO films on PC and PC/ABS to generate stable, hydrophobic surfaces. By examining the plasma conditions—deposition rate, energy range, and surface topography—ultrathin, stable films with advancing contact angles up to 110° and receding angles exceeding 90° can be designed. Storage of the siloxane films for 1 year in air at ambient conditions exhibits almost no aging. Thus, these films are superior to fluorocarbon films deposited for comparison.     

疏水高分子单链在疏水表面上吸附和扩散过程的分子动力学模拟

采用分子动力学模拟方法研究不同聚合度(N)的聚乙烯(PE)单链在Si(111)表面上的吸附和扩散行为. 分别设置相对介电常数为1和78模拟无溶剂和不良溶剂环境. PE单链的平衡吸附构象均呈现为二维吸附构象, 但在这两种截然不同的环境中呈现不同的构象和动力学特征, 说明溶剂环境对于疏水高分子单链在疏水表面上的吸附和扩散起到了很大的作用. 吸附能与聚合度呈线性关系, 单位链长的平均吸附能是-0.38 kJ·mol^-1. 另外, 扩散系数(D)与聚合度之间的标度关系是D~N^-3/2.     

两性离子聚合物的抗蛋白质吸附机理及其应用

两性离子聚合物是一类同时带有阴、阳离子基团的聚合物。依据分子结构,它主要包括磷酰胆碱型、磺基甜菜碱型、羧基甜菜碱型以及混合型两性离子聚合物等。两性离子聚合物溶液性质可以通过调节溶液的pH值来实现近似阳离子或阴离子聚电解质。两性离子聚合物又具有特殊的“反聚电解质效应”。另外,两性离子聚合物还具有极强的亲水性、优良的热和化学稳定性、优异的生物相容性以及良好的抗污染性能等特性。本文着重介绍了两性离子聚合在抗蛋白质吸附机理的研究进展,同时针对近年来两性离子聚合物在抗污染材料、药物及基因的运输载体、物质检测与分离材料等领域的应用进行了简要的概述。并且,就两性离子聚合物在这几个应用领域的发展前景进行了展望。     

不同表面性质聚电解质多层膜的制备及蛋白质吸附和血液相容性能

利用层层自组装方法制备了聚烯丙基铵盐酸盐(PAH)/聚苯乙烯磺酸钠(PSS)多层膜. 通过吸附或共价偶联, 在多层膜表面修饰了聚乙二醇(PEG)、牛血清白蛋白(BSA)或肝素, 通过石英晶体微天平(QCM)、椭圆偏振光谱和原子力显微镜(AFM)研究了多层膜的表面形貌及修饰方法对各种蛋白的吸附性能. 经修饰后的多层膜较基底膜的厚度均有所增大; 最外层经修饰后的多层膜吸附的BSA、纤维蛋白原及血浆蛋白的量较未修饰多层膜均有所减少. 采用SEM观察了血小板在多层膜上的黏附情况和形态变化, 计算了血小板的黏附率. 比较各多层膜的凝血酶原时间(PT), 发现修饰后的多层膜的凝血酶原时间均有所延长, 但各组间无显著性差异.     

Simultaneous Assessment of Kinetic,Site‐Specific,and Structural Aspects of Enzymatic Protein Phosphorylation

Protein phosphorylation is a widespread process forming the mechanistic basis of cellular signaling. Up to now, different aspects, for example, site‐specificity, kinetics, role of co‐factors, and structure–function relationships have been typically investigated by multiple techniques that are incompatible with one another. The approach introduced here maximizes the amount of information gained on protein (complex) phosphorylation while minimizing sample handling. Using high‐resolution native mass spectrometry on intact protein (assemblies) up to 150 kDa we track the sequential incorporation of phosphate groups and map their localization by peptide LC‐MS/MS. On two model systems, the protein kinase G and the interplay between Aurora kinase A and Bora, we demonstrate the simultaneous monitoring of various aspects of the phosphorylation process, namely the effect of different cofactors on PKG autophosphorylation and the interaction of AurA and Bora as both an enzyme–substrate pair and physical binding partners.     

蛋白质在羟基磷灰石界面吸附的研究

考察了酪蛋白酸钠(sodium caseinate,SC)和乳清分离蛋白(whey protein isolate,WPI)在表面性质不同的3种羟基磷灰石(hydroxyapatite,HA)颗粒上的界面吸附,分析了蛋白质的分子构型和HA颗粒的表面性质等因素对蛋白质在HA界面吸附的影响,重点讨论了SC和WPI肽链上磷酸化丝氨酸基团(phosphorylated serine residues,Ser-P)的数量和分布对吸附差异的影响.通过傅里叶变换红外光谱和表面电位分析发现SC和WPI无法被比表面积较小的HA颗粒有效吸附,但是在有效吸附面积较高的球状纳米HA和棒状微米HA上能够被吸附.Ser-P的存在使得SC在HA界面的吸附量更高、吸附能力更强.Ser-P数量和分布的不同则导致了SC中不同的蛋白组分在HA界面的竞争性吸附:β-酪蛋白在2μmHA界面始终存在优先吸附性;当纳米HA的浓度低于15 mg/mL时,纳米HA界面会优先吸附αs-酪蛋白.     

Modification of Active Carbon by Hydrophobic Plasma Polymers: II Fabric Substrates

Active carbon, used in various types of chemical protection devices, can absorb an extremely wide range of hazardous compounds. Unfortunately, this universal absorption includes ubiquitous water molecules, which can result in saturation and premature loss of efficacy. The purpose of this work has been to treat active carbon-impregnated fabric with appropriate low-pressure plasmas, so as to render the carbon surface hydrophobic, while minimally affecting its ability to absorb toxic gases or vapors (simultated here by CCl₄). The best results have been achieved using plasma polymerization of organosilicon (PP-HMDSO) thin films onto the fabric surface: This has been done in a pilot-scale microwave plasma reactor system, designed for treating continuously-moving flexible web materials up to 30 cm in width. Under optimal treatment conditions, a plasma exposure duration of 10 s (PP-HMDSO film thickness, d 40 nm) is found to be sufficient to reduce water absorption by 85%, while the corresponding reduction in CCl₄absorption is small (<20%). The treatment demonstrates long-term stability, and it holds promise for commercial implementation on existing roll coaters.     

Adhesion Aspects of Plasma Polymerized Acetonitrile and Acrylonitrile on Polypropylene Surface

Acetonitrile and acrylonitrile were plasma polymerized on Polypropylene (PP) surface. Surface modifications were characterized by surface energy measurements and ATR-FTIR spectroscopy. Surface energy measurement showed incorporation of hydrophilic groups along with deposition of cross-linked network of plasma-polymerized product. ATR-FTIR analysis of modified films showed incorporation of conjugated imine and amine groups. Using change in the relative intensities of C—H stretch bands of polypropylene surface, site of attachment of hydrophilic group and most predominant surface chemical reaction could be inferred. Chemical nature of plasma polymerized product was studied using FTIR by KBr disc method. Adhesion test was performed on modified surface by peel test method. Surface energy and peel strength measurements were performed for the samples aged for 2 months in order to check the durability of surface modification.     

蛋白质在固体表面吸附的研究进展

蛋白质在固体表面的吸附有多种理论模型和实验分析.蛋白质吸附主要包括分子传递、吸附、重排、交换、解吸等步骤.蛋白质在表面的状态由表面性能、静电作用及蛋白质自身性质等因素决定.蛋白质分子在界面吸附后发生构象改变,引起熵增.     

十八烷基聚氧乙烯表面空间结构和蛋白质吸附行为研究

为探讨聚合物-水界面十八烷基聚氧乙烯链(SPEO)空间结构和白蛋白选择性吸附行为的内在联系,本文采用聚甲基丙烯酸甲酯接枝十八烷基聚氧乙烯(PMMA-g-SPEO),通过不同热处理方式获得了具有“环形链”(A)和“尾形链”(B)结构的两种模型表面.在A表面,水相接触角随水化时间的延长而迅速降低,最终亲水性的界面可同时有效阻抗白蛋白和纤维蛋白原的吸附,但不呈现对白蛋白的选择性吸附;而在B表面,水相接触角随水化时间的延长变化不大,最终疏水性的界面可在有效阻抗纤维蛋白原的吸附同时,有效诱导白蛋白的选择性吸附,具有聚氧乙烯(PEO)阻抗非特异性吸附和十八烷基选择性吸附协同作用的特点.     

Atmospheric Pressure Plasma Surface Treatment of Polymers and Influence on Cell Cultivation

Atmospheric plasma treatment is an effective and economical surface treatment technique. The main advantage of this technique is that the bulk properties of the material remain unchanged while the surface properties and biocompatibility are enhanced. Polymers are used in many biomedical applications; such as implants, because of their variable bulk properties. On the other hand, their surface properties are inadequate which demands certain surface treatments including atmospheric pressure plasma treatment. In biomedical applications, surface treatment is important to promote good cell adhesion, proliferation, and growth. This article aim is to give an overview of different atmospheric pressure plasma treatments of polymer surface, and their influence on cell-material interaction with different cell lines.     

Surface Interactions of Radicals During Plasma Processing of Polymers

Surface interactions of radical species were investigated using the imaging of radicals interacting with surfaces (IRIS) technique during plasma surface modification of polymers. Three plasma systems were investigated by spatially probing the laser induced fluorescence of individual radical species and determining their surface scattering coefficients, S. The behavior of CF₂ moieties on polymer surfaces was studied using the fluorocarbon plasmas C₂F₆ and hexafluoropropylene oxide (HFPO). Three types of surface interactions were observed, surface generation of CF₂ (S > 1), surface loss of CF₂ (S < 1), and unit scattering (S = 1). Surface loss of CF₂ was seen in HFPO plasmas, while CF₂ was generated in C₂F₆ systems. The differences between these systems is believed to be the result of different overall surface interactions, specifically film deposition in the HFPO system and etching in the C₂F₆ system. Using NH₃ plasmas, the surface interactions of NH₂ radicals with polymers was also investigated. Here, NH₂ is generated at the surface of polyethylene and polytetrafluoroethylene substrates, but is consumed on polyimide substrates. Ion effects were also investigated by placing a grounded mesh in the path of the molecular beam to remove charged species.     

Adsorption of Some Surfactants onto Polyvinyl Alcohol as Hydrophobic Polymer Surface

The adsorption of different types of nonionic and anionic surfactants from aqueous solutions onto polyvinyl alcohol has been studied at different temperatures using surface tension measurements. The nonionic surfactants show Langmuirian L-shape isotherms whereas the adsorption isotherms of the anionic surfactants exhibit segmoidal shape. The experimental adsorption isotherms could be fitted to the Langmuir equation and the values of Γ_max and A_min have been calculated. The effect of temperature on the adsorption process as well as on both efficiency and effectiveness of adsorption has been studied.     

Kinetic Aspects of the Adsorption on Aluminum Oxide Drying Agents Doped with Alkali Metal Ions

Fundamental dynamic (kinetic) aspects of the process in which water vapor interacts with the surface of drying agents that are synthesized on the basis of low-temperature modification of aluminum oxide produced from a pseudoboehmite-containing hydroxide and are modified (doped) with alkali atoms (K, Na). It is shown that the kinetics of adsorption on the samples under study, formed from the fine fraction (0.5–1.0 mm) of aluminum oxide adsorbents, can be described with the Glueckauf equation, which rather well describes the dynamics of water vapor absorption in the course of time. The equation parameters were determined: adsorption rate constants and the equilibrium adsorption capacities (a*). It was found that the alkaline modification of the surface of aluminum oxide adsorbents results in that a* increases (by ~40%) as compared with the unmodified drying agent. A correlation is observed between the equilibrium adsorption capacity of the samples under study and the acid-base properties of the surface.     

Plasma Surface Modification of Biomedical Polymers: Influence on Cell-Material Interaction

Polymers are commonly used in industry because of their excellent bulk properties, such as strength and good resistance to chemicals. Their surface properties are for most application inadequate due to their low surface energy. A surface modification is often needed, and plasma surface modification is used with success the past decades. In the past few years, also plasma surface modification for biomedical polymers has been investigated. For biomedical polymers, the surface properties need to be altered to promote a good cell adhesion, growth and proliferation and to make them suitable for implants and tissue engineering scaffolds. This review gives an overview of the use of plasma surface modification of biomedical polymers and the influence on cell-material interactions. First, an introduction on cell-material interaction and on antibacterial and antifouling surfaces will be given. Also, different plasma modifying techniques used for polymer surface modification will be discussed. Then, an overview of literature on plasma surface modification of biopolymers and the resulting influence on cell-material interaction will be given. After an overview of plasma treatment for improved cell-material interaction, plasma polymerization and plasma grafting techniques will be discussed. Some more specialized applications will be also presented: the treatment of 3D scaffolds for tissue engineering and the spatial control of cell adhesion. Antibacterial and antifouling properties, obtained by plasma techniques, will be discussed. An overview of research dealing with antibacterial surfaces created by plasma techniques will be given, antifouling surfaces will be discussed, and how blood compatibility can be improved by preventing protein adhesion.     

Tuning the Surface Properties of Oxygen-Rich and Nitrogen-Rich Plasma Polymers: Functional Groups and Surface Charge

Controlling the concentration and nature of functional groups in plasma polymer films by adjusting the flow ratio of constituent precursor gases can be exploited to tune the surface charge of the resulting coating. Plasma polymer films containing various concentrations of nitrogen and oxygen functional groups were deposited in a low-pressure capacitively-coupled glow discharge reactor by plasma polymerization of binary gas mixtures of a hydrocarbon (ethylene or butadiene) and a heteroatom source gas (ammonia and/or carbon dioxide). Increasing the flow ratio of heteroatom to hydrocarbon gases increased the concentration of bonded nitrogen or oxygen, including that of primary amine or carboxylic groups as determined by X-ray photoelectron spectroscopy and chemical derivatization procedures. The zeta potential of samples was measured using an electro-kinetic analyser in a diluted sodium chloride solution. The deposition parameters controlled the composition of the coatings, allowing to tune the surface charge to either positive (ammonia based films)—or negatively (carbon dioxide base films) values at physiological pH.     

疏水性聚丙烯酸酯人工晶状体的低温等离子体改性

通过低温等离子体表面改性技术对疏水性聚丙烯酸酯人工晶状体进行表面改性, 并对改性前后材料的表面结构、形貌和光学性能进行了表征. 静态水接触角结果显示, 经过氨等离子体处理后的人工晶状体亲水性效果最好, 同时最佳的改性时间为120 s, 改性功率为150 W. XPS分析结果进一步证实, 经等离子体处理后, 在人工晶状体表面引入了极性基团. 原子显微镜观察结果显示, 改性后材料表面更加凹凸不平, 粗糙度显著增加而透光率变化很小, 但过大功率改性的样品透光率明显下降. 时效性测试结果表明, 人工晶状体在改性14 d后疏水性恢复趋于稳定.