肝素化聚氨酯表面血小板粘附研究

作者通过表面活化点放大和引入侧链间隔来增加聚氨酯（ＰＵ）表面共价结合的肝素量与生物活性，用固－液接触角分析所得样品表面性质，同时进行肝素浓度测定及血小板粘附实验，结果证明，与肝素直接接枝到ＰＵ表面相比，本文方法表面接枝肝素量和生物活性均得到较大提高，其血小板粘附程度大为降低。     

聚乙烯醇缩丁醛接枝丙烯酰胺共聚物的生物医学性能研究

本文用实验方法测定了聚乙烯醇缩丁醛接枝前后的吸水率、接触角、蛋白吸附特性,表明接枝后由于吸水率加大,白蛋白吸附量提高,与水界面接触角下降,初步认为它的血液相容性将随之改善。以全凝血时间、复钙时间、血液灌流血小板下降率作为表征指标,测定了接枝前后材料抗凝血性能的变化。实验结果表明:接枝后全凝血时间、复钙时间明显加长,血小板下降率降低。实验还测定了接枝前后材料对血细胞作用以及对尿毒素的渗透性能,实验表明接枝后材料对血细胞不产生明显的影响,有效地改善了材料的渗透性能。 在此基础上,为确定适宜的亲疏水比例,实验还测定了接枝率对抗凝血性能的影响,结果表明在实验范围内接枝率12—25％较宜。实验还同时测定了接枝链长对抗凝血性能的影响,结果表明:接枝链长Mn>4×10~4时抗凝血性能较优。     

纳米碳改性聚氨酯复合材料的表面抗凝血性能

研究纳米碳改性聚氨酯聚合材料表面的血液相容性。将经过表面处理的纳米碳分散到聚氨酯体系中，制成聚氨酯／纳米碳复合薄膜。通过血小板荧光标记人全血灌注实验和羊全血体外循环等实验，观察和测定血小板在材料表面的粘附作用以及血液中血红蛋白浓度、纤维蛋白原浓度的变化，探讨纳米碳对聚氨酯抗凝血性能的影响。实验结果显示聚氨酯／纳米碳表面血小板的粘附明显低于单纯聚氨酯对照组：体外循环4h后，血液中血红蛋白浓度、纤维蛋白原浓度的变化程度减小。表明纳米碳与聚氨酯的复合可以提高材料的血液相容性。     

肝素涂层体外循环管道的制备及生物学性能评价

通过离子键方式将肝素分子结合于体外循环医用聚氯乙烯管道中 ,进行了体外转流抗凝血性能测定和细胞毒性、肌肉植入等生物学性能评价 ,结果显示肝素分子结合于聚氯乙烯材料表面 ,同时筛选出具有抗凝血活性和良好生物相容性的聚乙烯亚胺 肝素涂层方法。     

新型醛基化海藻酸钠-肝素复合涂层的制备及性能评价

研制一种新型基于多醛基海藻酸钠和肝素的复合涂层,并就其生物相容性和血液相容性进行实验和评价.通过高碘酸钠氧化海藻酸及重氮化处理肝素获得多糖分子片段,多糖分子片段通过共价交联固定于体外循环管路表面.通过红外及紫外扫描对固定的多糖分子片段进行定性及定量分析;通过血小板粘附实验及蛋白粘附实验对涂层管道的血液相容性进行评价;通过表面接触角实验评价涂层管路的亲水活性;通过凝血功能检测评价管路表面的抗凝血活性.结果显示:氧化海藻酸及重氮化处理后肝素在在管道表面固定确实;涂层组与未涂层组相比,血小板粘附量及血栓形成量均显著减少(P＜0.05);肝素涂层组(LMNH)组与空白对照(C)组相比,蛋白粘附量无显著差异(P＞0.05);海藻酸钠涂层(OSA)组、双涂层(OSA.LMNH)组与LMNH组相比,蛋白粘附量均显著减少(P ＜0.05);LMNH组、OSA.LMNH组APTT及TT时间均显著延长(P＜0.05),抗凝血性能优良;OSA组与C组相比,APTT时间显著延长(P＜0.05)具有一定的抗凝血性能;OSA组、OSA.LMNH组与C组相比,表面接触角明显减小(P ＜0.05);LMNH组与C组相比,表面接触角无显著差异(P＞0.05).实验结果表明,OSA涂层物具有更优的亲水性和抗蛋白粘附性,LMNH涂层物具有更优的抗凝血性能,多糖片段复合涂层综合了单涂层的优点,生物相容性和血液相容性较单涂层均明显改善.     

PEU/LCP生物材料抗凝血特性研究

针对研制的PEU/LCP生物材料,测定并计算了其表面张力和界面张力,结果显示PEU/LCP材料的界面张力近视为0 N/m.抗凝血实验表明,PEU/LCP材料表面亲水性的提高可以减少血小板的黏附,对延长凝血时间有一定的帮助,肝素化的PEU/LCP材料提高了其抗凝血性能.     

多嵌段聚氨酯材料的表面结构与生物相容性

人工心脏隔膜用的聚氨酯材料至少应具有抗凝和耐挠曲的性能。通常提高聚氨酯的耐挠曲性多从调整其本体结构来考虑。由于聚氨酯的本体结构与表面结构不同,在挠曲过程中本体的相分离变化会影响表面软段的取向行为。因此为了知道挠曲对聚氨酯抗血凝性能的影响,作者从1983年起通过自制的耐疲劳试验代,利用XPS,FT-ATR-IR,WAXD,SAXS,SALS和血小板粘附试验等方法,测得在疲劳过程中聚氨酯表面的微相分离程度下降,聚醚软段含量减少,并导致其抗凝血性能下降。这样作者便把聚氨酯在反复变形过程中的本体形态,表面结构和生物相容性间的关系联系起来了。     

肝素化医用高分子抗凝管的研究

肝素经低温等离子体接枝处理固定在医用高分子管内壁，获得了内壁光滑的且具有抗凝血功能的新颖材料。经凝血时间（ＣＴ）和凝血因子（ＫＰＴＴ、ＰＴ、ＴＴ）时间的测定，这种抗凝管具有显著的抗凝血功能，并且管壁上固定着的肝素不脱落，鼠血流经抗凝管后２４小时以上仍不会形成血栓，切口处也不渗血。经接触角测定和复钙时间测得，氩等离子体轰击并完成肝素接枝上高分子表面的最佳合成时间是１２秒。     

001 聚氨酯表面接枝左旋-丙交酯以改善细胞粘附性

[英]/Hsu Shan-Hui… //Biomaterials. - 2000, 21(4).-359～367 聚氨酯具有良好的生物相容性和力学性能,在心血管材料及其它生物医用材料领域得到广泛应用,但其表面的细胞粘附性较差,本文研究了运用等离子体引发表面接枝方法改善聚氨酯表面的细胞粘附性.市售聚氨酯溶于四氢呋喃铸成膜,用氩等离子体处理后在空气中放置一定时间,浸入溶有左旋丙交酯的甲苯中,脱气封管在70℃反应5h,得到表面接枝左旋丙交酯的PU膜.接触角测量显示等离子体处理后水接触角由73°下降到36.,接枝使接触角略有上升,但仍比未处理聚氨酯及聚左旋乳酸表面亲水性好.只用等离子体处理而未进行表面接枝的聚氨酯膜接触角会逐渐升高,原因是表面亲水基团的重新分布.表面接枝后即无此现象.ESCA分析显示处理后表面基团发生变化,O/C比上升,有新的表面基团形成,且结构也不同与本体聚合的聚左旋乳酸.经过如此表面接枝处理的聚氨酯膜对成纤维细胞的粘附性较未处理聚氨酯膜有了成倍增长,也优于仅用等离子体处理的聚氨酯膜,对上皮细胞的粘附情形也类似.SEM观察显示粘附在接枝处理后的聚氨酯膜表面的细胞更为伸展.而血小板在接枝处理过的聚氨酯膜表面的粘附量及活性明显下降.总之,运用等离子体引发聚氨酯表面接枝左旋丙交酯获得了更好的血液相容性,具有潜在的广泛应用前景. (陈晓东摘朴东旭校)     

聚氨酯—聚硅氧烷共聚物的表面性质与抗凝血性

本文通过衰减全反射红外光谱,透射电镜,扫描电镜,固-液接触角等分析测试研究了聚氨酯-聚硅氧烷共聚物的表面微观形态和表面性质,同时使用Lee White凝血时间测定和血小板扩张试验评价了聚合物的抗凝血性。实验结果表明,聚氨酯-聚硅氧烷共聚物具有硬段微区(30～60(?))-聚醚软段相的微相分离结构以及聚二甲基硅氧烷-聚氨酯基体的微相分离结构,同时聚氨酯-聚硅氧烷共聚物的临界表面张力在24～27达因/厘米,共聚物的抗凝血性既优于聚氨酯。又优于聚硅氧烷。     

Poly(DL-lactic acid) film surface modification with heparin for improving hemocompatibility of blood-contacting bioresorbable devices

This work describes a simple method to immobilize heparin by covalent bonding to the surface of poly(lactic acid) film with the aim of showing improved hemocompatibility. Carboxyl groups present in heparin molecules were activated by reaction with N-hydroxy-succinimide and allowed to react with free amino groups created at the surface of poly(DL-lactic acid) films by controlled aminolysis. Contact angle measurements and XPS analysis confirmed the binding. Quantification was determined by radioactivity using heparin labeled with tritium. The surface exhibited anti factor Xa activity, thus confirming the presence of bounded heparin that kept some biological activity. Finally platelets adhesion showed less platelet adhesion on heparin modified films as well as preserved morphology.     

Hemocompatibility of surface-modified, silicon-incorporated, diamond-like carbon films

The hemocompatibility of plasma-treated, silicon-incorporated, diamond-like carbon (Si-DLC) films was investigated. Si-DLC films with a Si concentration of 2at.% were prepared on Si (100) or Nitinol substrates using a capacitively coupled radiofrequency plasma-assisted chemical vapor deposition method using a mixed gas of benzene (C(6)H(6)) and diluted silane (SiH(4):H(2)=10:90). The Si-DLC films were then treated with O(2), CF(4) or N(2) glow discharge for surface modification. The plasma treatment revealed an intimate relationship between the polar component of the surface energy and its hemocompatibility. All in vitro characterizations, i.e. protein absorption behavior, activated partial thromboplastin time measurement and platelet adhesion behavior, showed improved hemocompatibility of the N(2-)- or O(2)-plasma-treated surfaces where the polar component of the surface energy was significantly increased. Si-O or Si-N surface bonds played an important role in improving hemocompatibility, as observed in a model experiment. These results support the importance of a negatively charged polar component of the surface in inhibiting fibrinogen adsorption and platelet adhesion.     

Surface characterization and platelet adhesion studies on polyurethane surface immobilized with C60.

Due to its distinctive molecular configuration, C60 and its derivatives have been the research focus in exploring its electrical, mechanical, optical, and even biological applications during the past decades. In this investigation, C60 molecules are grafted onto the polyurethane surface, which is pretreated with oxygen plasma activation, through amine-terminated silane coupling agents. ESCA analysis indicates that the C60 molecules spontaneously grafted onto the amine-terminated PU substrate through nucleophilic additions to the fullerene double bonds which fuse two six-membered rings. More amine functional groups are formed on the PU surface if 4-aminobutyldimethylmethoxysilane is used as the coupling agent. In vitro platelet adhesion assay shows the C60 grafted PU are more platelets activating than the nontreated PU control. This might be attributed to the synergistic effect of the grafted C60 molecules and the few residual amine functional groups which are left after the C60 grafting reaction. Further applications using these C60 grafted polyurethane surfaces as the cell adhesion and cell growth substrates are currently under exploration.     

In vitro study of blood-contacting properties and effect on bacterial adhesion of a polymeric surface with immobilized heparin and sulphated hyaluronic acid

The blood-contacting properties and the effect on bacterial adhesion of a material based on polyurethane and poly(amido-amine) (PUPA), both in its native form and with the anticoagulant molecules heparin or sulphated hyaluronic acid (HyalS3.5) electrostatically bonded to its surface, were evaluated and compared in vitro. The presence of the biological molecules on the surface was revealed by a dye test and ATR/FTIR analysis. Bound heparin was found to maintain its physiological action, in terms of thrombin inactivation, as well as did free heparin. Moreover, it reduced the degree of platelet adhesion. On the contrary, bound HyalS3.5 lost its anticoagulant activity, though it reduced platelet adhesion. The number of platelets on both modified surfaces was low. Their shape distribution, as determined by SEM, did not differ significantly on the two modified surfaces or with respect to the bare PUPA surface. HyalS3.5 and heparin also inhibited adhesion of Staphylococcus epidermidis to the material. A possible relationship between the platelet and bacterial adhesion is ascribed to the mediating role of plasma proteins.     

Adhesion and stability of blood cells onto polymer substrates: effect of glow discharge

The adhesion of platelets, red blood cells, and lymphocytes onto various polymer substrates, hydrophobic to hydrophilic in nature, has been studied. Cell adhesion is found to be higher on hydrophilic substrates. The stability of these adhered cells has also been studied under a flow rate of 20 ml/min. Further the effect of glow discharge treatment onto various substrates is investigated. It seems the stability is more on glow discharge treated substrates due to increased surface free energy.     

Platelet adhesion to heparin coated oxygenator fibers under in vitro static conditions: impact of temperature

Heparin coating of cardiopulmonary bypass (CPB) circuitry may attenuate the platelet consumption associated with CPB. We investigated the effect of temperature on the interaction between platelet and heparin coated surfaces under in vitro static conditions. Heparin coated and non coated oxygenator fibers were incubated with heparinized whole blood at 37 degrees C and 22 degrees C. The incubation time was set at 30, 60, 180, and 300 minutes. The number of platelets adhering to each fiber was assessed with enzyme immunoassay using monoclonal antibody against platelet receptor protein CD 61(GPIIbIIIa). As an index of platelet activation, plasma soluble(s) P-selectin levels were measured by enzyme-linked immunosorbent assay. Under normothermia, the number of adherent platelets on the non coated surface increased significantly after 300 min of incubation. Platelet adhesion was reduced significantly by heparin coating of the surface and was kept constant after 300 min. Under hypothermia, heparin coating was also associated with significant reduction of platelet adhesion. The levels of sP-selectin did not correlate with the extent of platelet adhesion. Our results suggest that heparin coating is effective in decreasing platelet adhesion to the synthetic surface tested regardless of the temperature under static conditions. Inhibition of platelet activation on the heparin coated surface may be masked by standard dose heparinization.     

Synthesis and antithrombogenicity of heparinized polyurethanes with intervening spacer chains of various kinds

Heparin was immobilized to polyetherurethaneurea membrane by covalent or ionic bondings with intervening spacer chains having different lengths and different terminal functional groups. The amount of immobilization of heparin and the release rate of immobilized heparin were controlled by the nature and the mode of bonding of spacer chains. The heparinized polyetherurethaneurea membranes became more in vitro antithrombogenic and suppressed more strongly the adhesion and activation of platelets, as the amount of immobilization increased. It was also shown that the membrane to which the low-molecular-weight fraction of heparin was immobilized was less stimulating to platelets.     

In vitro study of blood-contacting properties and effect on bacterial adhesion of a polymeric surface with immobilized heparin and sulphated hyaluronic acid

The blood-contacting properties and the effect on bacterial adhesion of a material based on polyurethane and poly(amido-amine) (PUPA), both in its native form and with the anticoagulant molecules heparin or sulphated hyaluronic acid (HyalS3.5) electrostatically bonded to its surface, were evaluated and compared in vitro. The presence of the biological molecules on the surface was revealed by a dye test and ATR/FTIR analysis. Bound heparin was found to maintain its physiological action, in terms of thrombin inactivation, as well as did free heparin. Moreover, it reduced the degree of platelet adhesion. On the contrary, bound HyalS3.5 lost its anticoagulant activity, though it reduced platelet adhesion. The number of platelets on both modified surfaces was low. Their shape distribution, as determined by SEM, did not differ significantly on the two modified surfaces or with respect to the bare PUPA surface. HyalS3.5 and heparin also inhibited adhesion of Staphylococcus epidermidis to the material. A possible relationship between the platelet and bacterial adhesion is ascribed to the mediating role of plasma proteins.     

Glow discharge plasma treatment of polyethylene tubing with tetraglyme results in ultralow fibrinogen adsorption and greatly reduced platelet adhesion

Previous studies from our lab have shown that fibrinogen adsorption (Gamma(Fg)) must be reduced below 10 ng/cm(2) to significantly reduce platelet adhesion, and that radio frequency glow discharge (RFGD) treatment of polymeric films in the presence of tetraethylene glycol dimethyl ether (tetraglyme) can reduce Gamma(Fg) to the desired ultralow value. In this report, the effects of RFGD coatings of tetraglyme on the lumenal surface of PE tubing on Gamma(Fg) and on blood interactions both in vitro and ex vivo are described. Gamma(Fg) on the tetraglyme-coated PE tubing was reduced to the desired ultralow level (<10 ng/cm(2)), and we also observed a significant decrease in adsorption of von Willebrand's factor. In vitro platelet adhesion from washed platelet suspensions, platelet rich plasma, or whole blood to tetraglyme-coated PE tubing was decreased compared to PE, polyurethane, or silicone rubber tubes. In addition, thrombin generation by platelets adherent to tetraglyme-coated PE was also much less than by platelets adherent to PE. When inserted in an ex vivo carotid artery-carotid artery shunt in sheep, the RFGD tetraglyme-coated PE exhibited a very low number of adherent platelets compared to heparin-coated, chromic acid-etched, or plain PE. The RFGD tetraglyme-coated PE tubes exhibited high protein and platelet resistance in vitro, and high platelet resistance ex vivo. The improved hemocompatibility is attributed to the unique chemical structure of RFGD tetraglyme that makes it highly protein resistant.     

Adsorption of baboon fibrinogen and the adhesion of platelets to a thin film polymer deposited by radio-frequency glow discharge of allylamine.

Platelet adhesion under static and flow conditions from a washed platelet suspension containing albumin to a polymer deposited by radio-frequency glow discharge of allylamine vapour on a poly(ethylene terephthalate) substrate was measured. Electron spectroscopy for chemical analysis was used to characterize the surface. Fibrinogen adsorption from a series of dilute plasma solutions to radio-frequency glow discharge/allylamine, measured using 125I radiolabelled baboon fibrinogen, increased with decreasing plasma dilution to a level much higher than that previously observed on polyurethanes. Elutability by sodium dodecyl sulphate of fibrinogen adsorbed from dilute plasma also increased with increasing plasma concentration, but fibrinogen preadsorbed from plasma became non-elutable when surfaces were stored in buffer for 5 d before contact with sodium dodecyl sulphate. Platelet adhesion to substrates which had been pre-adsorbed with dilute plasma was measured using baboon platelets radiolabelled with 111In. Adhesion greatly decreased as the plasma concentration used for preadsorption increased, suggesting that non-specific platelet binding to the bare surface occurs when protein coverage is incomplete. Non-specific platelet binding was inhibited to varying degrees by preadsorption of different proteins to the surface. Platelet adhesion to surfaces preadsorbed with dilute (1.0%) baboon and human plasmas lacking fibrinogen (i.e. serum, heat-defibrinogenated plasma and congenitally afibrinogenemic plasma) was diminished compared with normal plasma. Addition of exogenous fibrinogen to the deficient plasma partially restored platelet adhesion to normal levels. Adhesion to surfaces preadsorbed with human plasma deficient in von Willebrand factor was comparable to that observed with normal plasma. The plasma preadsorption studies with fibrinogen deficient media suggested that adsorbed fibrinogen is necessary for platelet adhesion to the radio-frequency glow discharge/allylamine substrate at high protein coverage. However, since adhesion was greatly reduced when the plasma preadsorbed substrate was stored in buffer before platelet contact, the conformation of adsorbed fibrinogen is also important in mediating platelet adhesion to radio-frequency glow discharge.