聚丙烯微孔膜表面肝素化及其对低密度脂蛋白的吸附特性

为了赋予聚丙烯微孔膜(PPMM)选择性吸附低密度脂蛋白(LDL)的能力,发展了一种有效的PPMM表面共价固定肝素的方法.基于紫外引发丙烯酸的接枝聚合,通过碳二亚胺活化,以乙二胺为间隔臂,将肝素共价固定于PPMM表面,获得表面肝素化的PPMM.ATR-FTIR和XPS分析确证了修饰过程中膜表面基团及化学成分的变化.采用静...     

交联结构对肝素/壳聚糖层层组装多层膜内皮细胞相容性的影响

采用1-乙基-(3-二甲基氨基丙基)碳酰二亚胺交联技术对具有抗凝血抗菌作用的肝素/壳聚糖多层膜进行交联, 研究了交联结构对多层膜稳定性和血管内皮细胞亲和性的影响. QCM-D结果显示, 交联可有效地提高多层膜的稳定性, 在模拟人体血液流速(3.0 cm/s)下保持良好的稳定. 体外内皮细胞的研究结果显示, 多层膜的交联可有效地调节肝素/壳聚糖多层膜表面粘弹性, 并显著增加内皮细胞的粘附与生长. 交联的肝素/壳聚糖多层膜有望成为理想的心血管功能界面涂层材料.     

共价键合多层肝素薄膜修饰涂有硅橡胶的人工血管

报道一种采用医用硅橡胶涂层作软支撑共价键合多层肝素薄膜修饰人工血管等生物医学装置使其表面具有抗凝血性能的方法. 该项技术首先在人工血管的表面上涂上医用硅橡胶作为软支撑, 再在硅橡胶涂层的表面上涂上全氟磺酸(Nafion), 为接下来的层层静电组装提供活性基团. 然后将带正电荷的二苯胺重氮树脂(PA)和带负电荷的肝素分子(Hep)通过静电吸引作用交替沉积到全氟磺酸涂层的表面上. 紫外可见吸收光谱和傅立叶红外光谱数据表明, 在紫外光照射下, 重氮树脂的重氮基团与肝素的硫酸基团之间发生光化学反应, 生成硫酸酯, 使膜内层间离子键转变成共价键, 从而使肝素多层膜的稳定性大大提高. 研究表明经层层自组装和光化学反应后肝素分子呈现良好的抗凝血性能. 人工血管肝素化表面中的肝素分子以壁面结合的方式存在, 在人工血管表面固化肝素和抗凝血酶-III (AT-III)形成的络合物显示出较好的抗凝血性. 硅橡胶涂层使肝素分子与人工血管表面有一定距离, 有利于提高抗凝血性能. 在四个双层之内, 肝素对凝血酶失活的影响随着PA/Hep双层数目增加而增加, 说明了只有最外层的肝素才对凝血酶失活有直接影响. 该方法操作工艺简单, 重复性好, 可较广泛地适用于在多种生物医用装置和多孔组织工程支架材料的表面制备稳定的抗凝血涂层, 具有良好的应用前景.     

磷酯酰乙醇胺与硬脂酸和十八醇二元混合体系单层膜的热力学特性和AFM观测

利用表面压力-平均分子面积(π-A)曲线的关系, 分别研究了在水/空气界面上形成的磷酯酰乙醇胺(PE)与硬脂酸(SA)和十八醇(OD)二元混合体系的热力学特性. 根据对弹性模量(C_S^-1)、过量分子面积(A_ex)以及表面过量吉布斯自由能(ΔG_ex)等热力学参数的数据计算, 定量分析了混合单层膜分子之间的相互作用. 实验结果表明, PE/SA和PE/OD单层膜两种组分之间摩尔比对其热力学参数有影响. 热力学分析表明, 在X_SA=0.2, 0.8和X_OD=0.8处, PE/SA和PE/OD二元混合体系的热力学参数[过量分子面积(A_ex)和表面过量吉布斯自由能(ΔGex)]相对理想状态均表现为负偏差作用, 说明分子之间的作用为引力作用. 相反, PE/OD二元体系在X_OD=0.2, 0.4, 0.6处, 表现为正偏差作用, 这说明分子之间的作用为斥力作用. AFM观测为PE/SA和PE/OD单层膜热力学特性的理论分析提供了有力的支持.     

(肝素/壳寡糖/Pluronic(R))静电组装多层膜的构建

以壳寡糖/Pluronic(R)聚合物纳米聚集体(COPNs)、肝素为组装基元构建仿(肝素/壳聚糖)多层膜,验证多层膜负载疏水药物的可行性.Pluronic(R)P123与1,3-丙烷磺内酯反应合成末端磺酸化的Pluronic(R)聚合物,其与Pluronic(R)F127在水溶液中自组装形成表面带负电荷的混合胶束.利用壳寡糖与混合胶束的静电作用,获得COPNs,粒径与表面电位分析、透射电镜表征COPNs为直径(27.61±2.46) nm、表面zeta电位(6.12±1.82)mV、稳定的球形结构.石英晶体微天平(QCM)跟踪检测证明COPNs与肝素可在基材表面实现交替沉积;原子力显微镜(AFM)表征多层膜表面拓扑形貌,证明COPNs在表面沉积过程中稳定.将疏水的荧光探针芘载入COPNs参与多层膜的构建,荧光光谱实验结果表明多层膜可成功包载芘,且多层膜内芘的载入量与组装层数相关.以葛根素为模型药物,载药量测定与体外释药实验结果表明多层膜具有包载和缓释疏水药物的能力.     

亲水膜的表面改性及在膜蒸馏中的应用

膜的微孔性和疏水性是水溶液膜蒸馏的两个基本条件,迄今人们均采用疏水性高分子材料制成疏水微孔膜用于膜蒸馏研究。本文采用辐照接枝聚合和等离子体表面聚合的方法,将亲水的醋酸纤维素微孔膜和硝酸纤维素微孔膜表面疏水化改性,成功地用于膜蒸馏研究,大大扩展了疏水微孔膜的材料来源。实验结果表明,亲水膜表面改性得到的疏水膜,其膜蒸馏性能不低于疏水材料制成的膜,尤其是等离子体聚合法可以实现多种特殊单体在多孔的材料表面聚合,成为制备高性能疏水微孔膜的有效手段,为膜蒸馏的深入发展和实用化创造了有利条件。     

基于多巴胺自聚合及肝素固定改善钛的血液相容性

利用多巴胺自聚合及肝素固定的方法对纯钛进行表面修饰, 以改善其血液相容性. 采用水接触角测量、 X射线光电子能谱(XPS)和甲苯胺蓝法(TBO)等方法对所修饰的材料进行了表征. 采用溶血实验检测了材料的溶血性能, 并结合活化部分凝血活酶时间(APTT)测试和血小板黏附实验对所修饰材料的血液相容性进行了评价. 结果表明, 多巴胺能够在钛表面实现自聚合, 肝素可以共价接枝在聚多巴胺层上, 经肝素修饰后的材料的表面亲水性显著提高, 而且具有较低的溶血率, APTT时间显著延长, 血小板的黏附数量和被激活程度也显著降低. 因此, 纯钛经多巴胺自聚合以及肝素接枝修饰后的血液相容性得到了显著改善, 有望成为具有抗凝血功能的新型心血管植入材料.     

聚乙烯表面接枝聚合改性及抗凝血性的研究

聚乙烯(PE)膜经Ar等离子体预处理,无光引发剂紫外光照接枝甲基丙烯酸缩水甘油酯(GMA),然后进行肝素化处理,以改善PE的抗凝血性能。用正交实验确定接枝反应的最优条件。通过X-射线光电子能谱(XPS)、衰减全反射红外光谱(ATR-FTIR)、扫描电子显微镜(SEM)和接触角测定PE膜接枝GMA前后表面性能和表面形貌。用复钙时间、凝血酶原时间、部分凝血活酶时间、凝血酶时间和血小板粘附实验对其抗凝血性能进行评价,结果表明,被修饰PE膜的抗凝血性能显著提高。     

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.     

聚全氟乙丙烯中空纤维膜研究

以聚全氟乙丙烯(FEP)为成膜聚合物,复合无机粒子为成孔剂,邻苯二甲酸二辛酯(DOP)为稀释剂,采用熔融纺丝工艺制备得到FEP中空纤维膜.分析和讨论了不同成膜体系对FEP中空纤维膜热性能、动态力学性能和力学性能的影响,并对膜的纯水通量和孔径分布进行表征.用扫描电子显微镜(SEM)观察了膜的横断面和表面形貌.结果表明,所得FEP中空纤维膜为由溶出微孔和界面微孔组成的海绵状孔结构.随着成孔剂含量的增加,成孔剂在成膜体系中分散程度变差,容易发生团聚,最终导致膜孔径变大,孔径分布变宽.成孔剂和稀释剂对FEP中空纤维膜的热性能和动态力学性能影响较小.当FEP含量增加到70 wt％时,膜表面容易形成一层致密层,降低了膜的通透性.     

Immobilization of bovine serum albumin onto porous polyethylene membranes using strongly attached polydopamine as a spacer

Based on the self-polymerization and strong adhesion characteristics of dopamine in aqueous solution, a novel and convenient approach was developed to immobilize protein onto porous polyethylene (PE) membranes. A thin polydopamine (pDA) layer was formed and tightly coated onto PE membrane by dipping simply the membrane into dopamine aqueous solution for a period of time. Subsequently, bovine serum albumin (BSA) was bound onto the obtained PE/pDA composite membranes via the coupling between BSA and the reactive polydopamine layer. The firm immobilization of polydopamine layer and BSA was verified by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results of water contact angle measurement showed that the hydrophilicity of PE membrane was significantly improved after coating polydopamine and binding BSA. The experiments of blood platelet adhesion indicated that BSA-immobilized PE membrane had better blood compatibility than the unmodified PE and the PE/pDA composite membranes. The investigations on hepatocyte cultures and cell viability revealed that the polydopamine coating endowed PE membrane with significantly improved cell compatibility. Compared to BSA surface, polydopamine surface is more favorable for cell adhesion, growth, and proliferation.     

HYDROPHILIC MODIFICATION OF PPESK POROUS MEMBRANES VIA AQUEOUS SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

Hydrophilic surface modification of poly(phthalazinone ether sulfone ketone)(PPESK) porous membranes was achieved via surface-initiated atom transfer radical polymerization(ATRP) in aqueous medium.Prior to ATRP.chloromethyl groups were introduced onto PPESK main chains by chloromethylation.Chloromethvlated PPESK(CMPPESK) was fabricated into porous membrane through phase inversion technique.Hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate)(P(PEGMA)) brushes were grafted from CMPPESK membra...     

Mussel adhesive protein mimetic polymers for the preparation of nonfouling surfaces

A new biomimetic strategy for modification of biomaterial surfaces with poly(ethylene glycol) (PEG) was developed. The strategy exploits the adhesive characteristics of 3,4-dihydroxyphenylalanine (DOPA), an important component of mussel adhesive proteins, to anchor PEG onto surfaces, rendering the surfaces resistant to cell attachment. Linear monomethoxy-terminated PEGs were conjugated either to a single DOPA residue (mPEG-DOPA) or to the N-terminus of Ala-Lys-Pro-Ser-Tyr-Hyp-Hyp-Thr-DOPA-Lys (mPEG-MAPD), a decapeptide analogue of a protein found in Mytilus edulis adhesive plaques. Gold and titanium surfaces were modified by adsorption of mPEG-DOPA and mPEG-MAPD from solution, after which surface analysis by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy confirmed the presence of immobilized PEG on the surface. The ability of modified surfaces to resist cell attachment was examined by culturing 3T3 fibroblasts on the surfaces for up to 14 days. Quantitative image analysis revealed that cell adhesion to mPEG-DOPA and mPEG-MAPD modified surfaces decreased by as much as 98% compared to control surfaces. Modified Ti surfaces exhibited low cell adhesion for up to 2 weeks in culture, indicating that the nonfouling properties of mPEG-DOPA and mPEG-MAPD treated surfaces persist for extended periods of time. This strategy paradoxically exploits the strong fouling characteristics of MAP analogues for antifouling purposes and may be broadly applied to medical implants and diagnostics, as well as numerous nonmedical applications in which the minimization of surface fouling is desired.     

Photoinduced graft polymerization of 2-methacryloyloxyethyl phosphorylcholine on polyethylene membrane surface for obtaining blood cell adhesion resistance

Phospholipid polymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)], was grafted with polyethylene (PE) membrane using photoinduced polymerization technique to make the membrane resistant to cell adhesion. The water contact angle on the PE membrane grafted with poly(MPC) decreased with an increase in the photopolymerization time. This decrease corresponded to the increase in the amount of poly(MPC) grafted on the PE surface. The same graft polymerization procedure was applied using other hydrophilic monomers, such as acrylamide (AAm), N-vinylpyrrolidone (VPy) and methacryloyl poly(ethylene glycol) (MPEG). These monomers were also polymerized to form grafted chains on the PE membrane, and the grafting was confirmed with X-ray photoelectron spectroscopy. Analysis of amount and distribution of plasma proteins at the plasma-contacting surface of the original and the modified PE membranes were analyzed using immunogold assay. The grafting of poly(MPC) and poly(VPy) on PE membrane reduced the plasma protein adsorption significantly compared with that on the original PE membrane. However, the PE membranes grafted with poly(AAm) or poly(MPEG) did not show any effects on protein adsorption. Platelet adhesion on the original and modified PE membranes from platelet-rich plasma was also examined. A large number of platelets adhered and activated on the original PE membrane. Grafting with poly(AAm) did not suppress platelet adhesion, but grafting with poly(MPC) or poly(VPy) on the PE membrane was effective in preventing platelet adhesion. It is concluded that the introduction of the phosphorylcholine group on the surface could decrease the cell adhesion to substrate polymer.     

LLDPE/SMA共混膜表面接枝PEG的研究

聚乙烯综合性能优良且价格低廉,但由于较低的表面能和惰性化学结构,其着色性、生物相容性及制品表面涂饰性能差,与各种涂饰剂的粘结强度很低,限制了其用途的拓展,须进行表面改性.聚乙烯制品的表面改性方法已有不少研究报道[1~4],相对而言,采用添加表面改性剂的方法在工艺上仍最     

Separation of planar chiral ferrocene derivatives on beta-cyclodextrin-based polymer supports prepared via ring-opening metathesis graft-polymerization

A plastic microfluidic system, containing porous poly(vinylidene fluoride) (PVDF) membranes adsorbed with bovine serum albumin (BSA), is demonstrated for high resolution chiral separation of racemic tryptophan and thiopental mixtures. Microfluidic networks on poly(dimethylsiloxane) (PDMS) substrates are fabricated by capillary molding technique. This miniaturized chiral separation system consists of two layers of PVDF membranes which are sandwiched between two PDMS slabs containing microchannels facing the membranes. On-line adsorption of BSA onto the membranes is employed for the preparation of chiral stationary phase and the evaluation of solution conditions in an effort to achieve maximum protein adsorption. Variations in the mobile phase conditions, including solution pH and ammonium sulfate concentration, are studied for their effects on chiral separation. Based on the large surface area to volume ratio of porous membrane media, adsorbed BSA onto the PVDF membranes enables high resolution separation of racemic mixtures with sample consumption of sub-nanogram or less in the integrated microfluidic networks. In addition, the membrane pore diameter in the submicron range eliminates the constraints of diffusional mass-transfer resistance during protein adsorption and chiral chromatographic processes.     

MOLECULAR ENGINEERING STUDIES ON NONTHROMBOGENIC BIOMATERIALS--A NOVEL CLASS OF NONTHROMBOGENIC BIOMATERIALS WITH ZWITTERIONIC STRUCTURE OF CARBOXYBETAINES

N,N-dimethyl-N-methacryloyloxyethyl-N-carboxyethyl ammonium (DMMCA) was graft-copolymerized onto the surface of segmented poly(ether urethane) (SPEU) and PE film. The carboxybetaine structure on SPEU and PE film surfaces was confirmed by ATR-FTIR, XPS and water contact angle measurements. Through the experiments with platelet adhesion and protein adhesion assay in vitro, the two materials studied, including poly-DMMCA gel, all show excellent nonthrombogenicity. This confirms once again that the zwitterionic molecular structure on the surfaces of materials is essential for improving their nonthrombogenicity and biocompatibility.     

Effect of positively charged short peptides on stability of cubic phases of monoolein/dioleoylphosphatidic acid mixtures

To elucidate the stability and phase transition of cubic phases of biomembranes with infinite periodic minimal surface is indispensable from biological and physicochemical aspects. In this report, we investigated the effect of positively charged peptide-3K (LLKKK) and poly(L-lysine) on the phase stability of monoolein (MO) membranes containing negatively charged dioleoylphosphatidic acid (DOPA) (i.e., DOPA/MO membranes) using small-angle X-ray scattering. At first, the effect of peptide-3K on 10% DOPA/90% MO membrane in excess water, which is in the Q229 phase, was investigated. At 3.4 mM peptide-3K, a Q229 to Q230 phase transition occurred, and at >3.4 mM peptide-3K, the membrane was in the Q230 phase. Poly(L-lysine) (M(w) 1K-4K) also induced the Q230 phase, but peptide-2K (LLKK) could not induce it in the same membrane. We also investigated the effect of peptide-3K on the multilamellar vesicle (MLV) of 25% DOPA/75% MO membrane, which is in L(alpha) phase. In the absence of peptide, the spacing of MLV was very large (11.3 nm), but at > or = 8 mM peptide-3K, it greatly decreased to a constant value (5.2 nm), irrespective of the peptide concentration, indicating that peptide-3K and the membranes form an electrostatically stabilized aggregation with low water content. Poly(L-lysine) also decreased greatly the spacing of the 25% DOPA/75% MO MLV, indicating the formation of a similar aggregation. To compare the effects of peptide-3K and poly(L-lysine) with that of osmotic stress on stability of the cubic phase, we investigated the effect of poly(ethylene glycol) with molecular weight 7500 (PEG-6K) on the phase stability of 10% DOPA/90% MO membrane. With an increase in PEG-6K concentration, i.e., with an increase in osmotic stress, the most stable phase changed as follows; Q229 (Schwartz's P surface) --> Q224 (D) --> Q230 (G). On the basis of these results, we discuss the mechanism of the effects of the positively charged short peptides (peptide-3K) and poly(L-lysine) on the structure and phase stability of DOPA/MO membranes.     

聚乙烯在羟基化β-石英(100)表面上的有序吸附

利用分子动力学模拟方法研究了聚乙烯链在羟基化β-石英(100)表面上的吸附. 结果表明, 吸附基底上的规则图案起到模板的作用, 无论是真空还是溶液环境, 都会引导聚乙烯链在表面形成二维沿着[110]方向取向的折叠构型. 为了与聚乙烯的吸附相比较, 进一步研究了聚氧化乙烯链在相同表面上的吸附情况. 结果表明, 极性链与非极性链在极性表面上的吸附情况完全不同.