壳聚糖静电吸附羧基磷酰胆碱聚合物的研究

采用饥饿法聚合合成了3种不同配比的甲基丙烯酰氧乙基磷酰胆碱-甲基丙烯酸二元共聚物(poly(MPC-co-MA),PMA),并将其静电吸附在壳聚糖表面(CS-PMA)。通过动态接触角(DCA)对影响静电吸附改性的盐及聚合物组成因素进行研究。用X-射线光电子能谱(XPS)、原子力显微镜(AFM)对改性壳聚糖膜的表面元素组成、形貌进行表征,并通过血小板黏附实验对其抗凝血性能进行评价。结果表明,这种利用静电吸附的方式将磷酰胆碱聚合物吸附在壳聚糖表面,可获得具有仿细胞外层膜结构的涂层表面。与壳聚糖相比,改性后壳聚糖可以显著降低对血小板的黏附,抗凝血性能显著提高。该研究为构建仿细胞外层膜结构改善材料血液相容性提供了一种简单、便捷的方法。     

仿细胞外层膜结构修饰壳聚糖涂层的研究

采用自由基聚合合成甲基丙烯酰氧乙基磷酰胆碱(MPC)-甲基丙烯酰氧丙基三甲氧基硅(TSMA)二元共聚物(poly(MPC-co-TSMA),PMT),将其涂覆在交联壳聚糖(CS-GA)表面通过三乙胺蒸汽或高温催化处理,使聚合物中的三甲氧基硅基团在交联的同时键合CS-GA表面的氨基或羟基。动态接触角(DCA)和X-射线光电子能谱(XPS)对改性后壳聚糖表面的结果表明,该聚合物可以在交联壳聚糖表面获得较为稳定的具有仿细胞外层膜结构的涂层表面(CS-GAPMT)。该方法简单实用,有望在生物材料表面改性、药物控释和组织工程等领域具有潜在的应用前景。     

磷酰胆碱共聚物的合成及膜的生物相容性

为了研究磷酰胆碱类聚合物的生物相容性,以偶氮二异丁腈(AIBN)为引发剂,采用自由基聚合制备了系列2-甲基丙烯酰氧乙基磷酰胆碱(MPC)与甲基丙烯酸丁酯(BMA)、甲基丙烯酸异辛酯(EHMA)的共聚物PMB、PMEH.用红外光谱、元素分析、核磁共振等方法对其结构进行了表征并探讨了其在不同溶剂中的溶解性,为该类物质的提纯提供依据;通过溶剂挥发法制备了共聚物薄膜,血小板黏附实验显示,含有MPC的聚合物薄膜比不含MPC的聚合物薄膜有更好的血液相容性;溶胀度测试显示MPC聚合物薄膜有非常好的吸收水的能力,且平衡含水量(EWC)会随着MPC在聚合物薄膜中含量的增加而增加,当MPC在PMB20中的摩尔含量为18%时,平衡含水量可以达到47%,这是磷酰胆碱类聚合物薄膜具有优良生物相容性的原因之一.     

改善生物医用高分子膜表面血液相容性的PC技术

为提供解决生物材料血液相容性的有效途径,介绍了起源于细胞膜模拟思想的磷酰胆碱(PC,phosphorylcholine)技术,以及用PC技术来改善生物医用高分子膜表面血液相容性的最新方法,包括属于物理方法的共混改性、表面涂层,属于化学方法的表面接枝、半贯穿聚合物网络.此外,还介绍了两种与PC技术并行的提高生物医用高分子膜血液相容性的方法.     

仿贻贝磷脂聚合物的合成及其仿生涂层的构建

为改善纯钛表面的抗凝血性能,合成了一系列磷酸胆碱仿生聚合物,并在其表面构建了稳定的仿生涂层,通过一系列实验、表征和评价优化出更有利于钛材表面改性的磷酸胆碱聚合物。首先采用简单的自由基聚合法和羧基与氨基的反应,分两步合成了5种不同比例的2-甲基丙烯酰氧乙基磷酰胆碱(MPC)、甲基丙烯酸(MA)和多巴胺(DA)的无规共聚(PMMDA3-Q、PMMDA3-T、PMMDA5-Q、PMMDA5-T、PMMDA7),并通过FTIR、1 H NMR、GPC以及UV-Vis等完成了定性、定量表征和分析。通过自组装的方式,将5种不同聚合物分别组装到钛表面,并采用QCM-D、AFM及血小板粘附实验考察了5种聚合物在钛表面的组装量、表面粗糙度以及改性后的钛表面抗血小板粘附及抑制血小板激活的能力。结果表明,聚合物PMMDA7更适合作为钛材表面改性聚合物,为构建磷酸胆碱仿生多功能涂层提供了实验基础和方法。     

磷酰胆碱类似物在有机硅材料表面的常压等离子体引发接枝改性研究

采用He常压辉光放电等离子体(APGDP)处理有机硅薄膜材料表面并引发2-甲基丙烯酰氧乙基磷酰胆碱(MPC)在其表面接枝聚合.通过ATR-FTIR对接枝前后膜表面的结构进行表征分析,确定MPC共价接枝到材料表面.改性后膜表面的接触角由101°下降到54°,在室温下保存15天后仍维持在58°左右,表明接枝MPC后有机硅材料获得高亲水性的表面,并能使这一性质较好地保持.接枝前后膜的力学性质变化不大.体外血小板粘附实验表明,接枝MPC后的材料表面能够显著抑制血小板的粘附和聚集,具有优良的血液相容性,可以作为一种新型医用生物弹性体.     

膜蒸馏脱盐用超疏水复合膜的研制

通过溶胶凝胶法和表面涂覆法,先后在PVDF中空纤维膜表面引入亲水SiO_2纳米粒子和低表面能PDMS涂层,构建具有高粗糙度、低表面能的超疏水复合膜,并探究SiO_2粒径、SiO_2溶液涂覆时间、PDMS涂覆时间等条件对复合膜性能的影响。SiO_2/PVDF复合膜接触角只有25.8°,而PDMS/SiO_2/PVDF复合膜接触角则达到162.3°,膜蒸馏通量约24.5 kg/(m~2·h);在60 h质量分数3.5%氯化钠盐溶液膜蒸馏测试中性能稳定,截留率始终保持在99.8%以上.     

水溶性壳聚糖衍生物在壳聚糖膜表面的化学固定及抗凝血性能研究

合成了N-双取代亚甲基磷酸壳聚糖,并且对其进行了表征。通过戊二醛交联的方法将N- 双取代亚甲基磷酸壳聚糖固定在壳聚糖薄膜表面。对接枝前后膜表面的结构性能和血液相容性进行表征,结果显示N -双取代亚甲基磷酸壳聚糖被有效地固定在壳聚糖膜表面,并且能够有效地抑制血小板在壳聚糖膜表面的粘附。     

磺化聚苯乙烯/聚乙烯醇交联膜的制备与性能

以磺化度为75%的磺化聚苯乙烯(SPS)和聚乙烯醇(PVA)为原料,按一定的配比共混后浇铸成膜,在程序升温的过程中进行热交联,通过控制不同交联时间得到不同交联密度的交联膜.考察了交联膜的离子交换容量(IEC)、吸水率、溶胀性和尺寸稳定性;利用原子力显微镜和交流阻抗仪对交联膜的表面形貌及电导率进行了表征.结果表明:交联膜的IEC值略有降低;吸水率和溶胀度得到了很好的控制,具有较好的尺寸稳定性;膜表面出现了明显的亲水相和憎水相相分离,且亲水相微区的聚集尺寸和连续性随交联时间的长短而变化;随交联时间的延长,交联膜的电导率值略有下降,但交联后膜的室温电导率仍高于0.01 S/cm.     

辉光放电电解等离子体法制备羧甲基纤维素/聚乙二醇/丙烯酸高吸水性复合材料及其溶胀性能

在水溶液中,以丙烯酸(AA)、羧甲基纤维素(CMC)和聚乙二醇(PEG)为原料,N,N’-亚甲基双丙烯酰胺(MBA)为交联剂,用辉光放电电解等离子体(GDEP)引发制备羧甲基纤维素/聚乙二醇/丙烯酸(CMC/PEG/AA)高吸水性复合材料。采用红外光谱、X射线衍射、扫描电镜和热重分析对复合材料的结构、形貌和热稳定性进行了表征;研究了复合材料在蒸馏水、雨水、0.9%NaCl溶液、黄河水和自来水中的溶胀行为。结果表明,CMC、PEG和AA发生接枝共聚形成高吸水性复合材料,组分间相容性好,表面出现深浅不均匀的沟壑、孔洞和凹槽,热稳定性能良好;复合材料在蒸馏水、雨水和0.9%NaCl溶液中的最大平衡溶胀率分别约为935 g/g、689 g/g、78 g/g;在黄河水和自来水中溶胀动力学行为表现出过溶胀平衡特性,即材料先发生溶胀,达最大值后再逐渐消溶胀到平衡。     

Wettable phosphorylcholine-containing polymers useful in blood filtration

The use of phosphorylcholine (PC)-containing polymers has long been acknowledged as a method to improve the haemocompatibility of blood contacting devices. Such polymers were investigated for coating leukocyte filters, as a means of preserving precious platelet numbers and function. It was demonstrated that by use of such coated filters, the platelet recovery could be significantly increased by some 30%. This was however, balanced by a decrease in the leukocyte removal efficiency of the filter. More problematic however, was the poor critical wetting surface tension (CWST) of the filter (45 mNm^–1). This was due to the surface expression of the hydrophobic groups of the polymer in air. In order to obtain a filter that could be immediately wetted by the blood and hence remove the need for any detrimental priming of the filter, the PC polymer was modified in order to reduce its hydrophobic content. A series of new cross-linkable polymers was developed that contained other hydrophilic monomers, yet could film-form to produce a coating stable to fluid contact. These materials demonstrated the required wetting characteristics (a CWST of >78mNm^–1), whilst retaining the excellent blood-contacting properties.     

MMA/MPEOMA/VSA copolymer as a novel blood-compatible material: ex vivo platelet adhesion study

MMA/MPEOMA/VSA copolymers with both pendant polyethylene oxide (PEO) side chains and negatively chargeable side groups were synthesized by random copolymerization of methyl methacrylate (MMA), methoxy PEO monomethacrylate (MPEOMA; PEO mol. wt, 1000), and vinyl sulfonic acid sodium salt (VSA) monomers with different monomer composition to evaluate their blood compatibility. MMA/MPEOMA copolymer (with PEO side chains) and MMA/VSA copolymer (with negatively chargeable side groups) were also synthesized for the comparison purpose. The synthesized copolymers were coated onto polyurethane (PU) tubes (inner diameter, 4.6 mm) by a spin coating. The platelet adhesion of the MMA/MPEOMA/VSA copolymer-coated tube surfaces was compared with that of tube surface coated with MMA/MPEOMA or MMA/VSA copolymer with similar MPEOMA or VSA composition, using an ex vivo canine arterio-artery shunt method. The platelet adhesion was evaluated by radioactivity counting of technetium (99mTc)-labeled platelets adhered on the surfaces after 30 and 120 min of blood circulation. The MMA/MPEOMA/VSA copolymer (monomer molar ratio 9/0.5/0.5 or 8/1/1) was better in preventing platelet adhesion on the surface than the MMA/MPEOMA or MMA/VSA copolymer with similar MPEOMA or VSA composition, probably owing to the combined effects of highly mobile, hydrophilic PEO side chains and negatively charged VSA side groups.     

Examination of 2-methacryloyloxyethyl phosphorylcholine polymer coated acrylic resin denture base material: surface characteristics and <Emphasis Type="BoldItalic">Candida albicans</Emphasis> adhesion

The aim of this study is to evaluate the effects of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer coating with various concentrations onto acrylic resin denture base material on surface characteristics such as contact angle and surface roughness and on Candida albicans adhesion which is the major factor of denture stomatitis. Specimens, prepared from heat-polymerized acrylic denture base material, were divided into control and three test groups, randomly. Surfaces of the specimens in test groups were coated with poly(MPC) (PMPC) by graft polymerization of MPC in different concentrations (0.25?mol/L; 0.50?mol/L and 0.75?mol/L), while no surface treatment was applied to the control group. Contact angles and surface roughness were examined, and chemical composition of the surfaces was analyzed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (FTIR) to verify the presence of PMPC coatings. Then, specimens were incubated with C. albicans for 18?h and the number of adhered cells was determined. Upon PMPC coating, the contact angle values statistically decreased, but no difference was found in surface roughness values. A statistically significant decrease was observed in C. albicans adhesion in parallel with the increase in the MPC polymer concentration. There was no significant difference between 0.50?mol/L and 0.75?mol/L groups in terms of adhesion. These findings indicated that graft polymerization of MPC on acrylic denture base material reduces the adhesion of C. albicans, and may be evaluated as a coating for prevention of denture stomatitis.     

高分子复合黏胶体系对CL-20包覆及性能的影响

为了降低CL-20的机械感度,选择聚丙烯酸酯橡胶（HyTemp）和聚氨酯（TPU）作为黏结剂,微晶蜡作为钝感剂,对CL-20晶体表面进行包覆,分别制备了CL-20/HyTemp/微晶蜡、CL-20/TPU/微晶蜡、CL-20/HyTemp复配TPU/微晶蜡3种样品。分别通过扫描电子显微镜（SEM）、X射线衍射仪（XRD）、X射线光电子能谱仪（XPS）、差示扫描量热仪（DSC）、机械感度仪来表征样品的表面包覆情况、晶体结构、热稳定性以及机械感度。结果显示:HyTemp、TPU和微晶蜡都能有效包覆CL-20;且3种样品中CL-20的晶型仍为ε型,未发生改变。与包覆前相比,3种样品中氮元素含量均有大幅度的降低,包覆程度较高。其中,高分子复合黏结剂（HyTemp复配TPU）包覆样品的表面更为紧凑密实。与原料CL-20相比,复合黏结剂包覆样品的表观活化能提高了164.45 kJ/mol,熵变和焓变也有较大提升,反应活性降低,热稳定性明显改善;临界载荷由原料CL-20的60 N提高到了288 N,撞击感度也比原料CL-20降低了3.6 J,降感效果显著。采用HyTemp复配TPU作为黏结剂包覆的样品综合性能最好。     

Polystyrene/wood composites and hydrophobic wood coatings from water-based hydrophilic-hydrophobic block copolymers

 The combination of synthetic thermoplastic polymers and wood is normally problematic because wood surfaces are hydrophilic while typical thermoplastic polymers are hydrophobic. A possible solution is to use block copolymer coupling agents. In this work we show the use of a potentially useful synthetic method of producing hydrophilic-hydrophobic block copolymers as hydrophobic coatings and coupling agents in polystyrene/wood flour composites. In particular, wood veneers are coated with water-based emulsions of hydrophilic-hydrophobic block copolymers from styrene and methacrylic acid. Dried coated surfaces are shown to become hydrophobic through dynamic contact angle measurements. When wood flour is coated with the hydrophilic-hydrophobic block copolymer based on styrene and acrylic acid, significant improvement in the ultimate tensile properties of composites formed from coated wood flour/polystyrene mixtures is realized. Since no volatile organic compounds (VOCs) are used in coating wood surfaces and subsequent composite production, improvement in mechanical properties of thermoplastic/wood flour composites are shown to occur in environmentally responsible formulations. Received: 13 May 1999 / Accepted: 5 February 2000     

Controlled release of levofloxacin sandwiched between two plasma polymerized layers on a solid carrier

Targeted delivery and controlled local release of drugs has a number of advantages over conventional systemic drug delivery approaches. Novel platforms for local delivery from solid drug carriers are needed to satisfy the requirements of various medical applications, in particular for the incorporation and release of hydrophilic drugs from a solid carrier material. We have utilized the plasma polymerization of n-heptylamine for the generation of two thin coated layers that serve two distinct purposes. First, an n-heptylamine plasma polymer layer is applied onto the surface of the solid carrier material in order to facilitate spreading of the drug, which is applied by solvent casting; levofloxacin in ethanol was used for this study. A second n-heptylamine plasma polymer coating then serves as a thin barrier coating to control the release. We show that the rate of release can be adjusted via the thickness of the plasma polymer overlayer. We also show that this modality of controlled release of levofloxacin completely inhibits Methicillin-resistant Staphylococcus aureus (MRSA) colonization and biofilm formation on and near the coated biomaterial surface.     

Plasma-treated polyethersulfone coated with crosslinked poly(vinyl alcohol): composite membranes for pervaporation dehydration of ethanol

Composite membranes with crosslinked poly(vinyl alcohol) matrix as selective layer coated on a polyethersulfone supporting porous layer were prepared aiming at separating ethanol/water mixtures by pervaporation. A polyethersulfone asymmetric microporous membrane was synthesized by the wet phase inversion process. The support membrane was then exposed to air plasma to activate the surface. The selective dense layer was obtained by coating of PVA and a crosslinking agent over the polyethersulfone substrate, followed by thermal treatment. The morphology was examined by scanning electron microscopy (SEM) for both, support membrane and the coated polymeric layers. Surface physicochemical properties were evaluated through measuring the contact angle (θ) and the estimation of surface free energy (γ_S) and adhesion work. The surface chemical composition of support membrane and coated hydrophilic layers were characterized by infrared spectra with horizontal attenuated total reflectance (FT-IR/HATR). The swelling degree of PVA dense membranes, and the pervaporation performance of the crosslinked PVA/PES composite membranes, manufactured with several coating steps, were evaluated with water/ethanol (20/80 wt%) mixtures at temperatures in the range of 30–60 C. Results of the effective pervaporation dehydration of ethanol are discussed in terms of membrane morphology and the solution-diffusion transport mechanism.     

自然对流下强吸水表面上结霜特性的研究

在自行研制的强吸水表面上进行了结霜实验研究,测得了其上的霜表面温度随时间的变化情况,并与普通金属表面上的进行了对比.进行了不同实验条件下吸水表面上霜厚的测量,与普通金属表面进行了对比,研究了涂层厚度对结霜的影响.结果表明,这种涂层在较易结霜的实验条件下可使初始霜晶出现时间延迟555分钟左右,在低于冰点的一定范围内,初始霜晶出现可延迟3小时以上;并且霜厚减少可达40%以上,霜层疏松,在外力的作用下很容易除去.涂层越厚,吸水能力越强,抑霜作用也就越明显.     

Controlled adhesion of human lymphocytes on electrically charged polymer surface having phosphorylcholine moiety

The human lymphocytes were interacted with polymer surfaces whose surface potential was controlled by the formation of a polyion complex (PIC) having a phosphorylcholine moiety. 3-(Methacryloyloxypropyl)-trimethyl ammonium iodide as the cationic unit or potassium 3-methacryloyloxypropyl sulfonate as the anionic unit was copolymerized with 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butyl methacrylate. PIC was made at the solid–liquid interface, that is, an aqueous solution containing an anionic polymer with different concentrations was contacted with a cationic polymer coated polymer membrane. The formation process of PIC was followed using a quartz crystal microbalance, and the PIC surfaces were analyzed by ζ-potential and X-ray photoelectron spectroscopy. The surface potential on the PIC was controllable from +20 to −16 mV, which increased in the amount of adsorbed anionic copolymer as the ζ-potential decreased toward the negative charge. The PIC surface in contact with human lymphocyte for 5 h was observed using a scanning electron microscopy and the density of the adherent human lymphocyte was determined by the lactate dehydrogenase method. The lymphocyte adhesion on the surface was gradually reduced with an increase in the negative value of the ζ-potential. The morphological change in the adherent lymphocytes was not observed on the polymer surfaces with MPC units. The adherent lymphocytes were not activated on the PIC surface. The lymphocyte adhesion with reduced activation could be controlled by changing the surface potential on the polymer with the MPC unit.