聚氨酯/液晶(PU/EBBA)复合膜的血液相容性研究

以聚氨酯弹性体为基质材料,与液晶化合物EBBA共混后,由溶剂蒸发法浇铸成膜.偏光显微镜观察证实了复合膜中液晶相的存在.用动态凝血实验、血小板粘附实验和扫描电镜观察的方法研究了复合膜中液晶含量对材料抗凝血性能的影响.结果表明,只有当液晶含量达到30%(wt)时,复合膜的血液相容性随着液晶含量的增加有明显改善,同时发现复合膜表面吸附的血小板随着液晶含量的增加而明显减少.     

聚氨酯/液晶复合膜的抗凝血性能研究

以聚醚型聚氨酯为基质材料 ,分别与向列型、胆甾型液晶化合物在适当溶剂中溶解共混后 ,利用溶剂蒸发法在聚四氟乙烯板上浇铸成膜。详细研究了液晶含量对复合膜动态凝血性能 ,血小板粘附性能以及溶血性能的影响。研究结果表明 :只有当复合膜中的液晶重量份数超过 30 %时 ,复合膜才表现出良好的抗凝血性能 ,且随液晶含量的增加 ,复合膜的抗凝血性能有明显的改善 ,尤其是复合膜表面吸附的血小板数量随液晶含量的增加而明显减少     

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。     

姜黄素/聚乳酸—乙醇酸共聚物复合薄膜的制备及抗凝血研究

血管支架内再狭窄是血管支架临床应用中最突出的问题,药物洗脱支架的问世成为冠心病介入治疗的一个重要里程碑。但是目前的药物洗脱支架还存在抗凝血不足的问题,药物洗脱支架植入晚期血栓形成的病例在临床上有所报道。姜黄素具有抗增生以及抗凝血等多种药理活性,有望成为药物洗脱支架的新颖药物。我们以可降解高分子材料聚乳酸-乙醇酸共聚物(PLGA)为载体分别制备了三种浓度(3wt%、5wt%、8wt%)的姜黄素复合薄膜。采用傅立叶变换红外光谱研究了复合薄膜的组成成分,结果显示:姜黄素与PLGA的特征峰在复合薄膜的红外图谱中均有出现;体外血小板黏附实验结果显示姜黄素复合薄膜表面的血小板黏附数量减少,较少团聚、变形和激活;复合薄膜的部分凝血活酶时间(APTT)长于纯PLGA薄膜的APTT,这都表明姜黄素/聚乳酸-乙醇酸共聚物复合薄膜的抗凝血性能得到改善,且复合薄膜的抗凝血性能在实验药物浓度范围内随着药物含量的增加,材料的抗凝血性能进一步提高。     

姜黄素/聚乳酸－乙醇酸共聚物复合薄膜的制备及抗凝血研究

血管支架内再狭窄是血管支架临床应用中最突出的问题,药物洗脱支架的问世成为冠心病介入治疗的一个重要里程碑.但是目前的药物洗脱支架还存在抗凝血不足的问题,药物洗脱支架植入晚期血栓形成的病例在临床上有所报道.姜黄素具有抗增生以及抗凝血等多种药理活性,有望成为药物洗脱支架的新颖药物.我们以可降解高分子材料聚乳酸-乙醇酸共聚物(PLGA)为载体分别制备了三种浓度(3wt%、5wt%、8wt%)的姜黄素复合薄膜.采用傅立叶变换红外光谱研究了复合薄膜的组成成分,结果显示:姜黄素与PLGA的特征峰在复合薄膜的红外图谱中均有出现;体外血小板黏附实验结果显示姜黄素复合薄膜表面的血小板黏附数量减少,较少团聚、变形和激活;复合薄膜的部分凝血活酶时间(APTT)长于纯PLGA薄膜的APTT,这都表明姜黄素/聚乳酸-乙醇酸共聚物复合薄膜的抗凝血性能得到改善,且复合薄膜的抗凝血性能在实验药物浓度范围内随着药物含量的增加,材料的抗凝血性能进一步提高.     

聚乳酸共混聚三亚甲基碳酸酯生物膜的生物性能表征及动物实验研究

聚乳酸是一种很好的生物材料，具有很好的生物相容性及可降解性。在第一代聚乳酸膜的基础上我们研制了聚乳酸共混聚三亚甲基碳酸酯（PTMC）生物软膜，并对该复合材料进行了一系列的生物性能表征，包括细胞毒性实验、急性毒性实验、皮肤刺激实验、致敏实验、溶血实验、微核实验及皮下植入实验。结果表明，共混膜无毒，无刺激，无致敏作用，不引起溶血，试验材料组微核率为1．3％士1．0％，小于3％，骨髓微核实验呈阴性。皮下植入后各个时期伤口无红肿、化脓、坏死等现象。在应用于家兔术后预防肠黏连的实验研究中，生物软膜表现出很好的实验效果。结论：聚乳酸共混聚三亚甲基碳酸酯软膜具有很好的生物相容性。     

液晶复合膜的表面形貌特征及其血液相容性研究

目的:模仿生物膜的表面结构形态,制备液晶/聚氨酯复合膜,作为抗凝血生物材料;材料和方法:将胆甾醇液晶引入到聚合物中,制成液晶复合材料,利用偏光显微镜观察复合材料的表面形貌特征,并通过溶血率测试,动态凝血试验及血小板粘附试验探究液晶/PU复合膜的血液相溶性;结果:在聚合物基材中加入亲水性的胆甾醇液晶可使复合材料表面呈现有液晶微区的有序结构特征,复合膜表面的抗凝血性能提高;结论:胆甾醇液晶能明显改善材料的血液相容性,改善的程度与液晶的组成及复合膜中液晶的含量相关.     

聚多巴胺辅助溶胶-凝胶TiO_2薄膜表面固定牛血清白蛋白

在钛表面涂覆溶胶-凝胶TiO2薄膜,再利用聚多巴胺薄膜结合牛血清白蛋白(BSA)分子,以改善血液相容性。X射线光电子能谱分析表明TiO2薄膜表面形成了聚多巴胺薄膜和BSA分子层。接触角测试结果表明聚多巴胺薄膜和BSA分子层使试样的接触角升高,但表面能和界面张力下降。血液相容性实验表明,与TiO2涂层试样相比,结合BSA分子的试样具有更好的抗凝血性能和抗血小板聚集性能。     

聚氨酯

以聚醚型聚氨酯为基质材料，分别与向列型、胆甾型液晶化合物在适当溶剂中溶解共混后，利用溶剂蒸发法在聚四氟乙烯板上浇铸成膜。详细研究了液晶含量对复合膜动态凝血性能，血小板粘附性能以及溶血性能的影响。研究结果表明只有当复合膜中的液晶重量份数超过     

利用等离子体表面接枝技术提高医用聚氨酯血液相容性的研究

目的：聚氨酯作为与血液接触的植入物和组织器官替代材料在心血管系统有重要而广泛的应用前景,本研究采用等离子体表面接枝技术,通过“空间桥梁”在聚氨酯材料表面引入具有抗凝血功能的肝素分子,对材料表面的微观化学组成、表面接触角等理化性能进行了测定分析,并通过测定血小板在材料表面的粘附数量,对改性表面的抗凝血性能做了评价。结果：聚氨酯表面接枝肝素分子后,表面的氧／氮元素比提高,水接触角减小。对血小板的吸附和活化性下降,抗凝血性能得到提高。     

Blood-compatibility of polyurethane/liquid crystal composite membranes.

Polyurethane/liquid crystal composite membranes were first suggested to be used as biomaterials. In our work, three series of polyurethane/liquid crystal composite membranes based on three different kinds of liquid crystal compounds [N-(-4-methyoxybenzylidene)-4'-heptylaniline, 4-pentyl-4'-nitrile-biphenyl and cholesteryl oleyl carbonate] were prepared by casting on glass plates from a tetrahydrofuran (THF) solution of polymer and liquid crystal at room temperature. In our opinion, the formation of liquid crystal phase on the composite membrane surface is the basic requirement for getting better biomaterial. The result of this work is in accordance with our opinion. The effect of liquid crystal content on the formation of liquid crystal phase was identified by the observation of optical polarization microscopy (OPM). The results showed that the content of liquid crystal in composite membrane must be more than 30% (wt) in order to form liquid crystal phase on the composite membrane surface. The blood-compatibility of the composite membranes was assessed from SEM observation of the platelet's adhesion to membrane's surface, blood clotting time and haemolysis ratio. The observation of platelet's adhesion showed that the platelets gathered together on the pure polyurethane films, but the amount of platelets which were adherent on the surface covered by the liquid crystal phase was fewer than that of pure polyurethane film when platelet-rich plasma was allowed to be in contact with the membranes for 1 h at room temperature. The determination of blood clotting time and haemolysis ratio showed that these polyurethane/liquid crystal composite membranes, in which the content of liquid crystal was more than 30% (wt), appear to be beneficial in improving the blood compatibility and reducing the thrombogenicity.     

Preparation and blood compatibility of polysiloxane/liquid-crystal composite membranes

Polysiloxane/liquid crystal composite membrane was first suggested to be used as biomaterials. In this work, the polydimethyl-methylhydrosiloxane and polydimethyl-methylethylenesilosiane, as a substrate, were blended with cholesteryl oleyl carbonate (COC) in tetrahydrofuran, and then crosslinked into membranes on glass plates by means of the platinum catalyst at 110 degrees C for 20 min. The effects of the liquid-crystal content in composite membranes on the formation of liquid-crystal phase were verified by the observation of optical polarization microscopy. The relationship between the morphology of the composite membranes and blood compatibility was identified by the dynamic blood-clotting tests, haemolysis ratio measurement, platelet adhesion and SEM observation. The results show that the blood-compatibility of composite membranes with the concentration of liquid crystal 20, 30% (wt) is more excellent than that of other composite membranes.     

Preparation and Characterization of a Porous Scaffold Based on Poly(D,L-Lactide) and N-Hydroxyapatite by Phase Separation

In this study, a series of porous scaffolds were prepared from poly(D,L-lactide) (PLA) and nanohydroxyapatite (HA) using the phase separation method. HA/PLA composite membranes and PLA membranes with a microporous structure (pore size around 10–20 μm) were observed by scanning electron microscopy and these micropores were well distributed throughout the PLA membranes. The surface morphology of HA/PLA composite membranes was significantly improved compared to pure PLA membrane. Also, the mechanical property and contact angle of composite membranes were different from that of pure PLA films. The immortalized rat osteoblastic ROS 17/2.8 cell line was used in this research to study the cell adhesion and proliferation behavior, and the results indicated that composite membranes had great cell affinity and good biocompatibility.     

Preparation and characterization of a porous scaffold based on poly(D,L-lactide) and N-hydroxyapatite by phase separation

In this study, a series of porous scaffolds were prepared from poly(D,L-lactide) (PLA) and nanohydroxyapatite (HA) using the phase separation method. HA/PLA composite membranes and PLA membranes with a microporous structure (pore size around 10-20 μm) were observed by scanning electron microscopy and these micropores were well distributed throughout the PLA membranes. The surface morphology of HA/PLA composite membranes was significantly improved compared to pure PLA membrane. Also, the mechanical property and contact angle of composite membranes were different from that of pure PLA films. The immortalized rat osteoblastic ROS 17/2.8 cell line was used in this research to study the cell adhesion and proliferation behavior, and the results indicated that composite membranes had great cell affinity and good biocompatibility.     

Preparation and properties of nano-hydroxyapatite/PCL-PEG-PCL composite membranes for tissue engineering applications

Nano-hydroxyapatite (n-HA)/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) composite membranes were prepared by solvent casting and evaporation method. The structure and properties of the membranes were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle measurements, in vitro hydrolytic degradation, mechanical test, and cell culture. The effect of n-HA content on physical-chemical properties of the n-HA/PCEC composite membranes was studied. The results showed that the shape and size of micropores of the composite membranes changed with n-HA content increased; the tensile strength decreased with the increase of n-HA content. The osteoblast cell was cultured on the membranes, good cell attachment and growth manner were observed after postseeding for 1 day. MTT assays showed that the n-HA/PCEC membranes had no negative effect on the cell viability and proliferation. These results suggested that the obtained n-HA/PCEC composite membranes in this study might have prospective applications in tissue engineering field.     

Poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymers as surface additives for promoting chondrocyte attachment and growth

The poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymer was explored to engineer poly(D,L-lactic acid) (PLA) material to promote chondrocyte attachment and growth. The poly(D,L-lactic acid)-block-poly(ethylene glycol) copolymer (PLE) was synthesized by a coupling reaction between PLA and poly(ethylene glycol) (PEG) (M(n) 1000, 2000, and 4000 respectively), with the use of 4,4'-methylenediphenyl diisocyanate (MDI). Then the PLE was activated by methyl sulfonyl chloride and the amino acids or arginine-glycine-aspartic acid tripeptide (RGD) was attached, which was verified by the ninhydrin-UV method. The modified PLA films were simply prepared by blending PLA with PLE derivatives. ATR-FTIR, XPS, contact angle, and AFM results clearly showed that the PEG chain stably enriched on the surface of PLE-modified PLA films. The chondrocyte cytocompatibility test showed the modified PLA films could significantly improve chondrocyte attachment and proliferation.     

Preparation and characterization of ibuprofen-loaded poly(lactide-co-glycolide)/poly(ethylene glycol)-g-chitosan electrospun membranes

Ibuprofen-loaded composite membranes composed of poly(lactide-co-glycolide) (PLGA) and poly(ethylene glycol)-g-chitosan (PEG-g-CHN) were prepared by electrospinning. The electrospun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), mechanical evaluation and contact angle measurements. Shrinkage behavior of the membrane in buffer at 37 degrees C was also evaluated. It was found that PLGA glass transition temperature (Tg) decreased with increasing PEG-g-CHN content in the composite membranes, which results in a decrease in tensile stress at break but an increase in tensile strain of the membranes. The degree of shrinkage of these composite membranes decreased from 76 to only 3% when the PEG-g-CHN content in the membranes increased from 10 to 30%. The presence of PEG-g-CHN significantly moderated the burst release rate of ibuprofen from the electrospun PLGA membranes. Moreover, ibuprofen could be conjugated to the side chains of PEG-g-CHN to prolong its release for more than two weeks. The sustained release capacity of the PLGA/PEG-g-CHN composite membranes, together with their compliant and stable mechanical properties, renders them ideal matrices for atrial fibrillation.     

Fabrication and characterization of hydrophilic electrospun membranes made from the block copolymer of poly(ethylene glycol-co-lactide)

To improve the hydrophilicity, pliability, and egradability of some biodegradable polymers such as polylactide (PLA), a triblock copolymer, and poly(ethylene glycol-co-lactide) (PELA) has been electrospun into fibrous membranes in the fiber sizes of 7.5 microm to 250 nm. The relationship between electrospinning parameters (such as voltage, concentration, and feeding rate) and the fiber diameters has been investigated. The characterizations for the structure and morphology of electrospun membranes were carried out using differential scanning calorimetry (DSC), (1)H NMR, and scanning electron microscopy (SEM). The hydrophilicity of the membrane was determined by contact angle measurements in bi-distilled water, and it was shown that the hydrophilicity of the copolymer could be adjusted by the content of the poly (ethylene glycol) (PEG) segment in the copolymer. The results of in vitro degradation study showed that the submicrostructure of the fibrous membrane and the incorporation of hydrophilic PEG into PLA block could accelerate the degradation of the membrane in regards to the changes of inherent viscosity, tensile strength, and weight loss.     

An amphiphilic degradable polymer/hydroxyapatite composite with enhanced handling characteristics promotes osteogenic gene expression in bone marrow stromal cells

Electrospun polymer/hydroxyapatite (HA) composites combining biodegradability with osteoconductivity are attractive for skeletal tissue engineering applications. However, most biodegradable polymers such as poly(lactic acid) (PLA) are hydrophobic and do not blend with adequate interfacial adhesion with HA, compromising the structural homogeneity, mechanical integrity and biological performance of the composite. To overcome this challenge, we combined a hydrophilic polyethylene glycol (PEG) block with poly(d,l-lactic acid) to improve the adhesion of the degradable polymer with HA. The amphiphilic triblock copolymer PLA–PEG–PLA (PELA) improved the stability of HA–PELA suspension at 25 wt.% HA content, which was readily electrospun into HA–PELA composite scaffolds with uniform fiber dimensions. HA–PELA was highly extensible (failure strain >200% vs. <40% for HA–PLA), superhydrophilic (～0° water contact angle vs. >100° for HA–PLA), and exhibited an 8-fold storage modulus increase (unlike deterioration for HA–PLA) upon hydration, owing to the favorable interaction between HA and PEG. HA–PELA also better promoted osteochondral lineage commitment of bone marrow stromal cells in unstimulated culture and supported far more potent osteogenic gene expression upon induction than HA–PLA. We demonstrate that the chemical incorporation of PEG is an effective strategy to improve the performance of degradable polymer/HA composites for bone tissue engineering applications.