Influence of solution conditions on formation of amphiphilic hyperbranched polyanion/linear polycation multilayer films

Amphiphilic hyperbranched polyester (P2) consisting of a hydrophobic core, surrounded by aromatic carboxylic acids, is self-assembled into aggregates in aqueous solution at pH region of 3.8–4.7 and in THF–water mixed solution at THF/water volume ratio of 1/100–1/10. With P2 in both aqueous and THF–water mixed solution as polyanion and linear poly(diallydimethylammonium chloride) (PDAC) as polycation, self-assembled films were successfully formed by layer-by-layer dipping. The solution condition of P2, including the pH of aqueous solution and the THF/water volume ratio, affected not only the absorption behavior of P2 but also the surface morphology and hydrophilicity of the films with P2 as the outmost layer. At lower pH or higher THF/water volume ratio the aggregation of P2 in solution was enhanced, thus resulting in higher adsorption rate for P2, more rough and less hydrophilic surface for the films.     

Poly(N-vinylpyrrolidone)-modified surfaces repel plasma protein adsorption

The present work aimed to study the interaction between plasma proteins and PVP-modified surfaces under more complex protein conditions.In the competitive adsorption of fibrinogen(Fg) and human serum albumin(HSA),the modified surfaces showed preferential adsorption of HSA.In 100%plasma,the amount of Fg adsorbed onto PVP-modified surfaces was as low as 10 ng/cm~2,suggesting the excellent protein resistance properties of the modified surfaces.In addition, immunoblots of proteins eluted from the modified surfaces after plasma contact confirmed that PVP-modified surfaces can repel most plasma proteins,especially proteins that play important roles in the process of blood coagulation.     

聚二甲基硅氧烷/玻璃微流控芯片永久性粘合方法及其微通道表面改性研究及其应用

近年来,聚二甲基桂氧烷[Poly(dimethylsilloxane),PDMS]基质微流控芯片因其透光性能好,价格便宜,加工容易,适合大规模生产,成为微全分析系统(Micro total analysis system,μ-TAS)发展的一个热点^[1].PDMS易于复制微通道形状,且具有较高的保真度,省去了玻璃芯片刻蚀的复杂过程;而玻璃具有易于集成功能单元,散热性能好的优点,PDMS-玻璃杂合微流控芯片同时结合了PDMS和玻璃的优点,具有良好的发展前景^[2].     

Modulation of the functions of osteoblast-like cells on poly(allylamine hydrochloride) and poly(acrylic acid) multilayer films

Deposition of layer-by-layer polyelectrolyte multilayer (PEM) films has been a widely applied surface modification technique to improve the biocompatibility of biomaterials. The objective of this study was to investigate the impact of the deposition of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) multilayer films on adhesion, growth and differentiation of osteoblasts-like MG63 cells. PAH and PAA were deposited sequentially onto tissue culture polystyrene at either pH 2.0 or pH 6.5 with 4-21 layers. While the MG63 cells attached poorly on the PAH/PAA multilayer films deposited at pH 2.0, while the cells adhered to the PEM films deposited at pH 6.5, depending on layer numbers. Cell adhesion, proliferation and osteogenic activities (alkaline phosphatase activity, expression of osteogenic marker genes and mineralization) were highest on the 4-layer PAH/PAA film and decreased with increasing layer numbers. On the other hand, the behavior of MG63 cells did not show any difference on the adjacent even and odd layers, except PEM4 and PEM5, i.e. the surface charges of the PAH/PAA multilayer films with over ten layers seem indifferent to osteoblastic functions. The results in this study suggested that the mechanical properties of PEM films may play a critical role in modulating the behavior of osteoblasts, providing guidance for application of PEM films to osteopaedic implants.     

Influence of polyelectrolyte multilayer adsorption on the temperature sensitivity of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) (PNiPAM) microgels

The electrophoretic mobility and temperature-dependent particle size of poly(N-isopropylacrylamide) (PNiPAM) microgels after alternating adsorption of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) have been determined. First a PNiPAM-co-acrylic acid (AAc) shell was added to the PNiPAM microgel, then PDADMAC and PSS were adsorbed alternately. The studies of the electrophoretic mobility revealed charge reversal when a polyelectrolyte (PE) layer was adsorbed. Particle size measurements revealed a strong influence of polyelectrolyte adsorption on the temperature-dependent particle swelling. The strong influence of the adsorbed polyelectrolyte on the particle size is in contrast to polyelectrolyte multilayer adsorption on rigid particles.     

Poly(ethyleneimine) as reducing and stabilizing agent for the formation of gold nanoparticles in w/o microemulsions

This paper is focused on the use of branched poly(ethyleneimine) (PEI) as reducing as well as stabilizing agent for the formation of gold nanoparticles in different media. The process of nanoparticle formation was investigated, in the absence of any other reducing agents, in microemulsion template phase in comparison to the nucleation process in aqueous polymer solution.

On the one hand, it was shown that the polyelectrolyte can be used for the controlled single-step synthesis and stabilization of gold nanoparticles via a nucleation reaction and particles with an average diameter of 7.1 nm can be produced.

On the other hand, it was demonstrated that the polymer can also act as reducing and stabilizing agent in much more complex systems, i.e. in water-in-oil (w/o) microemulsion droplets. The reverse microemulsion droplets of the quaternary system sodium dodecylsulfate (SDS)/toluene–pentanol (1:1)/water were successfully used for the synthesis of gold nanoparticles. The polymer, incorporated in the droplets, exhibits reducing properties, adsorbs on the surface of the nanoparticles and prevents their aggregation. Consequently, nanoparticles of 8.6 nm can be redispersed after solvent evaporation without a change of their size.

Nevertheless, the polymer acts already as a “template” during the formation of the nanoparticles in water and in microemulsion, so that an additional template effect of the microemulsion is not observed.

The particle formation for both methods is checked by means of UV–vis spectroscopy and the particle size and size distribution are investigated via dynamic light scattering and transmission electron microscopy (TEM).     

Poly(ethylene glycol)-coated microfluidic devices for chip electrophoresis

Herein, we report on a strategy for durable modification of the channel surface in microfluidic glass chips with the neutral hydrophilic-coating material poly(ethylene glycol) PEG-1M-100. Applied in microchip electrophoresis such PEG-coated devices exhibit a suppressed electroosmotic flow and reduced analyte adsorption. The PEG-coated chips were successfully applied in chip electrophoresis of FITC-labelled amines and amino acids and native proteins as well as in chiral separations. The performance of the coated chips was found to be superior compared with uncoated microchips. The coated chips exhibited high stability and the relative standard deviation of migration times in PEG-coated devices was less than 2%.     

Synthesis of amphiphilic tri-block copolymerpoly(vinylpyrrolidone)-b-poly(methyl methacrylate)-b-poly(vinylpyrrolidone) for the modification of polyethersulfone membrane

Well-defined amphiphilic tri-block copolymer PVP-b-PMMA-b-PVP was prepared for the first time via successive reversible addition fragmentation chain transfer(RAFT) polymerization using carboxyl-terminated trithiocarbonate as the RAFT agent.The structure of the copolymer was characterized using FTIR,GPC and ~1H NMR.The block copolymer could be directly blended with polyethersulfone(PES) as a macromolecule additive using N-methyl-2-pyrrolidone(NMP) as the solvent to prepare membranes. The water contact angles for the modified membranes decreased obviously,and therefore,the protein adsorption amount on the membrane surface decreased.     

Adsorption of cationic polyelectrolyte onto a model carboxylic latex and the influence of adsorbed polycation on the charge regulation at the latex surface

 Adsorption of a well-characterized cationic polyacrylamide (CPAM) onto the surface of a model colloid (monodisperse polystyrene latex with carboxylic functional groups) was studied over a wide range of pH (4–9) and KCl concentration (c _s =10^-3–0.3 M). The surface charge density of the latex particles with and without adsorbed CPAM was also measured over the same range of electrolyte compositions. The adsorbed amount of CPAM increases with increase in c _s and pH. The polyelectrolyte adsorption alters substantially the surface charge density of the latex particles as compared to the polymer-free case. A large overcompensation of the surface charge by the adsorbed polyelectrolyte is established at high c _s and low pH. A qualitative explanation of the observed features is put forward. Received: 3 December 1996 Accepted: 20 January 1997     

Poly(methylglutamate)-coated surfaces in HPLC and CE

Summary Thermal polymerization of the N-carboxyanhydride of glutamic acid-5-methylester was used to coat microparticulate silica and the surface of capillaries with poly(methylglutamate) (PMG). By increasing the thickness of the PMG layer the hydrophobicity of the stationary phases could be increased. However, total shielding of surface silanols was not achieved. The PMG-coated silicas for HPLC showed unexpected and strange behavior in the chromatography of proteins. Nevertheless, capillaries coated with PMG proved to be excellent for highly efficient CE separations of proteins at medium pH values.     

氩等离子体后辉光区对聚四氟乙烯膜表面的优化改性

在理想管式反应器中, 采用Langmuir双电子探针和电子自旋共振(ESR)诊断技术分别定量测定了氩等离子体场中各活性物种的轴向分布, 并利用氩等离子体放电区及后辉光区对聚四氟乙烯(PTFE)进行了表面改性. 通过接触角测量、扫描电子显微镜和X 射线光电子能谱分析比较了改性前后常规及后辉光氩等离子体对PTFE表面结构及性能的影响. 结果表明, 氩等离子体中电子及离子浓度随轴向距离的增大迅速降低, 30 cm后接近于0, 而自由基浓度则降低缓慢, 40 cm处仍为初始浓度的96%. 氩等离子体放电功率、处理时间和气体流量强烈影响着PTFE表面润湿性的改善效果. 后辉光区因抑制电子和离子的刻蚀作用, 强化自由基反应, 使改性效果远优于常规氩等离子体. 经氩等离子体后辉光区短时间(30 s)处理后, PTFE表面化学成分发生了变化, F/C原子比从3.27降至2.30, O/C原子比从0.02增至0.09. 脱氟作用和含氧基团(如CO)的引入是有效改善PTFE表面润湿性的关键因素.     

超支化聚胺-酯改性聚二甲基硅氧烷微流控芯片的紫外检测应用

采用超支化聚胺-酯对经过氧气氛处理的PDMS微流控芯片表面进行改性.成功地将超支化聚胺-酯涂覆到PDMS表面,使其表面的接触角由108°±1°降到32°±20°,改善了其亲水性;改性过后通道内的电渗流得到了有效抑制,远低于未改性通道内的电渗流.同时,将芯片通过专门设计的通道与毛细管连接在一起,在紫外检测波长214nm,...     

Poly(Organophosphazenes): Use in the Improvement of Standard Materials. Application to the Modification of Surface Properties of Poly(Vinyl Alcohol)

Abstract

Modification of surface properties of poly(vinyl alcohol) by grafting of poly(organophosphazenes).     

以PEG为间隔基固定赖氨酸制备血液相容的聚氨酯材料

通过多步表面改性方法制备了血液相容性好的聚氨酯材料. 以PEG为间隔基将ε-赖氨酸通过Schiff碱反应和进一步的还原反应连接于聚氨酯表面. 该表面的水接触角和XPS结果表明, PEG和ε-赖氨酸成功接枝. 用蛋白质吸附和血栓溶解实验对材料的血液相容性进行了研究. 蛋白质吸附结果表明, 相对于改性前的聚氨酯, ε-赖氨酸改性后的表面能减少纤维蛋白原的吸附量近80%. 血栓溶解测试结果显示, ε-赖氨酸改性后的表面能够在13 min内使初生的血栓溶解. 这些结果证实, 改性后的表面不仅能抑制非特异性蛋白质的吸附, 而且在测试条件下能溶解初生的血栓.     

改性羟基磷灰石/聚乳酸纳米复合材料的结晶行为

利用溶剂复合的方法制备了具有良好生物相容性的表面接枝聚(γ-苄基-L-谷氨酸)的改性羟基磷灰石/聚乳酸纳米复合材料, 并研究了其熔融与结晶行为. 结果表明, 聚乳酸的玻璃化转变温度为60.3 ℃, 而复合材料的玻璃化转变温度达到65.8 ℃, 不同样品在140 ℃等温结晶后, 改性羟基磷灰石/聚乳酸复合材料的球晶直径仅为聚乳酸(PLLA)球晶直径的16.7%~66.7%. 复合材料的熔点提高到184.4 ℃.     

Poly(N‐vinylpyrrolidone)‐Modified Surfaces for Biomedical Applications

Poly(N‐vinylpyrrolidone) (PVP), an important water soluble synthetic polymer, has many desirable properties including low toxicity, chemical stability, and good biocompatibility. Since PVP is hemocompatible and physiologically inactive, it has been used as a blood plasma substitute. Surface modification with PVP has been investigated extensively over the past few years as a means of preventing nonspecific protein adsorption. PVP may therefore be seen as a promising antifouling surface modifier comparable to poly(ethylene glycol) (PEG). In this review, various approaches for the design and preparation of PVP‐modified surfaces are summarized and potential biomedical applications of these PVP‐modified materials are indicated. Finally, some perspectives on future research on PVP for surface modification are discussed.

     

Surface modification of poly(tetramethylene adipate-co-terephthalate) membrane via layer-by-layer assembly of chitosan and dextran sulfate polyelectrolyte multiplayer

The improvement of hydrophilicity and hemocompatibility of poly(tetramethylene adipate-co-terephthalate) (PTAT) membrane was developed via polyelectrolyte multilayers (PEMs) immobilization. The polysaccharide PEMs included chitosan (CS, as a positive-charged and antibacterial agent) and dextran sulfate (DS, as a negative-charged and anti-adhesive agent) were successfully prepared using the aminolyzed PTAT membrane in a layer-by-layer (LBL) self-assembly manner. The obtained results showed that the contact angle of as-modified PTAT membranes reached to the steady value after four bilayers of coating, hence suggesting that the full coverage was achieved. It could be found that the PTAT–PEMs membranes with DS as the outmost layer could resist the platelet adhesion and human plasma fibrinogen (HPF) adsorption, thereby prolonging effectively the blood coagulation times. According to L929 fibroblast cell growth inhibition index, the as-prepared PTAT membranes exhibited non-cytotoxic. Overall results demonstrated that such an easy, valid and shape-independent processing should be potential for surface modification of PTAT membrane in the application of hemodialysis devices.     

聚酰亚胺硅氧烷/聚酰亚胺两面异性复合膜的制备及性能研究

以氨丙基封端的聚二甲基硅氧烷(PDMS)、 4,4'-二氨基二苯醚(4,4'-ODA)和3,4,3',4'-联苯四酸二酐(s-BPDA)为原料, 合成了聚酰胺酸硅氧烷嵌段共聚物. 将此嵌段共聚物和聚酰胺酸(s-BPDA/4,4'-ODA)共混, 通过控制制膜条件, 利用各组分在不同溶剂中的溶解度的差别, 使聚酰亚胺硅氧烷富集在膜的上表面. 因为两相在结构和性质上的相似性, 当聚酰胺酸硅氧烷和聚酰胺酸混合时, 具有很好的相容性, 消除了两相间的界面, 从而制备了优异的聚酰亚胺硅氧烷/聚酰亚胺两面异性的复合膜材料. 利用X射线光电子能谱(XPS)和水滴接触角对此复合膜进行了表征, 证明了此复合膜的两面异性, 并对此复合膜进行了热性能和机械性能研究, 发现此薄膜保持了聚酰亚胺优异的性能.     

Stability and ageing of plasma treated poly(tetrafluoroethylene) surfaces

In this study CO₂, H₂/H₂O and H₂O low pressure plasma treatment of poly(tetrafluoroethylene) (PTFE) foils and of thin plasma deposited fluorocarbon polymer (PDFP) films with a structure close to PTFE was investigated. The properties of the plasma were analyzed by mass spectroscopy (MS) and optical emission spectroscopy (OES). The modified fluorocarbon surfaces were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy, spectroscopic ellipsometry, electrokinetic measurements and dynamic contact angle measurements in order to find optimized treatment conditions. The results of the surface modification were compared with respect to the efficiency of the plasma treatment and the stability of the modification effect at different ambient conditions. It was shown that the H₂O plasma treatment is the most effective process for the intended modification. The hydrophobic PTFE surface was converted into a more hydrophilic one. The introduced radicals after the H₂O plasma treatment can be utilized subsequently for post plasma reactions such as grafting processes.     

Some High Molecular Weight Phthalate Plasticizers for Poly (Vinyl Chloride) Resins

Naphthenic acids and alcohols were prepared by oxidation of naphthenes. Four different high molecular weight phthalates of the types bis-2-naphthene carboxyethyl phthalate and ethylene glycol bis(naphthenyl phthalate). These high molecular weight phthalates and di-n-octyl phthalate (DNOP), as a reference commercial plasticizer, were compounded with poly (vinyl chloride) (PVC) and evaluated as plasticizers. The high molecular weight phthalates were more sensitive to soapy water than DNOP. Volatility and resistance to kerosene extraction studies were markedly better than for DNOP. The new plasticizers have good compatibility with PVC resin.