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.     

壳聚糖/液晶复合水凝胶的制备及细胞相容性研究

 目的：基于仿生理念构建壳聚糖/液晶(CS/LC)复合水凝胶体系,通过观察复合水凝胶表面形貌和相分离结构、评价细胞相容性,探讨复合水凝胶体系中液晶微区结构形态对细胞行为的影响。方法：以CS为基底材料,复合具有一定流动和取向的羟丙基纤维素酯类LC,制备具有类生物膜结构的CS/LC复合基质,采用扫描电镜、X射线衍射等手段对复合材料进行表征分析,并进一步观察复合水凝胶对成纤维细胞活性的影响。结果：CS/LC复合水凝胶主要呈现非晶态,LC相以“岛屿”状态均匀分布于CS水凝胶基材中,与CS构成两相分离结构;细胞相容性实验表明复合水凝胶中嵌有连续分布的流动性LC畴有利于细胞的初始黏附与生长。结论：复合水凝胶的仿生结构及类组织黏弹性使其表现出良好的细胞相容性。     

液晶/聚氨酯复合基底影响rBMSCs成骨分化的研究

目的:模拟体内组织弹性微环境,构建液晶(OPC/PU)复合基底,探究复合基底弹性模量及液晶相区尺寸对大鼠骨髓间充值干细胞(rBMSCs)成骨分化的影响。方法:通过调节复合膜中液晶含量,制备不同弹性模量的液晶复合基底。采用偏光显微镜观察复合基底表面液晶相区结构;万能测试仪测量复合基底弹性模量;激光共聚焦显微镜观察rBMSCs的铺展、极化和骨架排列;CCK-8法检测rBMSCs的增殖速率;real-time PCR检测复合膜上的成骨分化标记物Ⅰ型胶原和骨桥蛋白的mRNA表达。结果:(1)复合基底中液晶含量增加,液晶相区数量及尺寸增加,复合基底的弹性模量降低,但仍保持在MPa数量级。(2)rBMSCs在液晶含量较低的OPC10-PU和OPC30-PU表面呈现较好的初始黏附、铺展和增殖。(3)成骨诱导初期及中期,rBMSCs在OPC10-PU上展示较高的Ⅰ型胶原和骨桥蛋白基因表达;诱导培养后期,rBMSCs在OPC30-PU和OPC50-PU上呈现出Ⅰ型胶原和骨桥蛋白基因的高表达,成骨分化的基因表达重点也从早中期的Ⅰ型胶原主要表达转变为后期的骨桥蛋白主要表达。结论:复合基底中液晶含量较低时,rBMSCs主要响应于基底弹性诱发的力学刺激产生细胞行为的变化;基底中液晶含量增加,rBMSCs能够感知到液晶的黏弹特性并与其发生强烈的相互作用,此时基底的弹性和液晶相区的黏弹特性可能均对rBMSCs的成骨分化产生重要影响。     

Aggregation and electro-optical effects in a ferroelectric (side-chain liquid crystalline polymer/low molecular weight liquid crystal) composite system

Aggregation and electro-optical effects in the binary mixture containing ferroelectric side chain liquid crystalline polymer (FLCP) and low molecular weight liquid crystal (FLC) have been investigated. The FLCP is miscible with FLC having a spiral texture. The binary mixture exhibits a smectic A, a smectic C, and a chiral smectic C phase. The pitch length in the chiral smectic C phase of the binary mixture increases with increasing weight fraction of FLC. The d-spacing of the smectic layer decreases slightly with increasing weight fraction of FLC. A reversible transparent-opaque (light scattering) change was observed in the chiral smectic C state upon application of positive and negative DC electric fields, respectively. Transparent and opaque states are stable when the applied electric field is removed.     

Anisotropic binders for polymer/liquid crystal dispersions

The synthesis and phase behavior of linear and crosslinked side-group epoxy polymers are described. These polymers are used in dispersons with low-molecular-weight liquid crystals, and the observation of phase separation in these systems is demonstrated.     

Interfacial agents for polymer/liquid crystal dispersions

Liquid crystals (LC) were covalently and ionically bonded to one (or both) end(s) of polystyrene chains. These compounds were tested as interfacial agents in polystyrene/liquid crystal dispersions. In case of covalent bonding, the additive is too much “soluble” in polystyrene and no interfacial activity is observed. Ionic bonding of the LC to polystyrene chains deeply changes the situation, all the other conditions being the same. The dipolar interactions of the ion pairs are clearly favorable to the localization of the additive at the polymer/LC interface. The higher polarity of the ammonium sulfonate pairs compared to the parent ammonium carboxylate ion pairs accordingly accounts for a higher interfacial activity.     

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.     

Chitosan/bioactive glass nanoparticle composite membranes for periodontal regeneration

Barrier membranes are used in periodontal applications with the aim of supporting periodontal regeneration by physically blocking migration of epithelial cells. The present work proposes a combination of chitosan (CHT) with bioactive glass nanoparticles (BG-NPs) in order to produce a novel guided tissue and bone regeneration membrane, fabricated by solvent casting. The CHT/BG-NP nanocomposite membranes are characterized in terms of water uptake, in mechanical tests, under simulated physiological conditions and in in vitro bioactivity tests. The addition of BG-NPs to CHT membranes decreased the mechanical potential of these membranes, but on the other hand the bioactivity improved. The membranes containing the BG-NPs induced the precipitation of bone-like apatite in simulated body fluid (SBF). Biological tests were carried out using human periodontal ligament cells and human bone marrow stromal cells. CHT/BG-NP composite membranes promoted cell metabolic activity and mineralization. The results indicate that the CHT/BG-NP composite membrane could potentially be used as a temporary guided tissue regeneration membrane in periodontal regeneration, with the possibility to induce bone regeneration.     

Preparation and antibacterial test of chitosan/PAA/PEGDA bi-layer composite membranes

Chitosan/poly(acrylic acid)/poly(ethylene glycol) diacrylate (PEGDA) composite membranes with a bi-layer configuration were prepared and their potential application as an antibacterial material was examined. A two-step process was adopted. A dope consisting of PEGDA, acrylic acid (AA) and a photoinitiator was cast and then UV-cured on a glass substrate to form a mechanically strong, dense membrane. Subsequently, the membrane was coated with a layer of solution composed of chitosan, AA and water. As the majority of AA diffused downwards into the supporting layer underneath, chitosan coagulated with residual AA to form a nano-layer on the top surface by means of UV irradiation. Low-voltage field-emission scanning electron microscopy was used to observe the membrane morphology and to measure the thickness of the top layer. Contact angle measurements indicated a top layer mixed with chitosan and poly(acrylic acid), which was confirmed by chemical composition analysis of X-ray photon spectroscopy. The antibacterial activities of the formed membranes were tested both with respect to a Gram-negative (Escherichia coli) and a Gram-positive (Staphylococcus aureus) bacteria.     

Preparation and antibacterial test of chitosan/PAA/PEGDA bi-layer composite membranes

Chitosan/poly(acrylic acid)/poly(ethylene glycol) diacrylate (PEGDA) composite membranes with a bi-layer configuration were prepared and their potential application as an antibacterial material was examined. A two-step process was adopted. A dope consisting of PEGDA, acrylic acid (AA) and a photoinitiator was cast and then UV-cured on a glass substrate to form a mechanically strong, dense membrane. Subsequently, the membrane was coated with a layer of solution composed of chitosan, AA and water. As the majority of AA diffused downwards into the supporting layer underneath, chitosan coagulated with residual AA to form a nano-layer on the top surface by means of UV irradiation. Low-voltage field-emission scanning electron microscopy was used to observe the membrane morphology and to measure the thickness of the top layer. Contact angle measurements indicated a top layer mixed with chitosan and poly(acrylic acid), which was confirmed by chemical composition analysis of X-ray photon spectroscopy. The antibacterial activities of the formed membranes were tested both with respect to a Gram-negative (Escherichia coli) and a Gram-positive (Staphylococcus aureus) bacteria.     

Peripheral blood cell separation through surface-modified polyurethane membranes

Cell separation from peripheral blood was investigated using surface-modified polyurethane (PU) membranes with different functional groups. Both red blood cells and platelets could pass through unmodified PU and PU-SO(3)H membranes, whereas the red blood cells preferentially passed through PU-N(C(2)H(5))(2) and PU-NHC(2)H(4)OH membranes. The permeation ratio of T and B cells was <25% for the surface-modified and unmodified PU membranes. CD34(+) cells have been recognized as various kinds of stem cells including hematopoietic and mesenchymal stem cells. The adhesiveness of CD34(+) cells on the PU membranes was found to be higher than that of red blood cells, platelets, T cells, or B cells. Overall, the adhesiveness of blood cells on the PU membranes increased in the following order: red blood cells 相似文献   

Nonporous polyurethane membranes as islet immunoisolation matrices--biocompatibility studies

Novel elastomeric nonporous polyurethane membranes were synthesised with differing hard segment contents for evaluation as possible islet encapsulation matrices. Physico-chemical properties of these membranes were reported earlier by authors and have been found suitable for immunoisolation. In the present study, membranes were evaluated for their in vitro biocompatibility. Membranes T1, T4, T5 and T6 did not show toxicity in direct cell contact study towards L929 fibroblasts. However, T2 and T3 were found cytotoxic and were excluded from further testing. NIH3T3 cells when exposed to leach out products of T4, T5 and T6 showed no cytotoxicity, while T1 decreased cellular viability as confirmed by MTT assay. T4 and T5 alone were seen to be compatible with mouse islets while T6 was incompatible to the mouse islets. Digital image analysis (DIA) studies showed intact morphology of islets cultured on the T4 and T5 with viability (88.4 and 91% respectively) comparable to islets on tissue culture polystyrene (TCPS) control. Islets on T4 and T5 also retained their functionality, as judged by insulin secretion in response to in vitro glucose challenge (16.0 mM). These studies point out the crucial role of surface free energy and hydrophilicity in deciding compatibility of polyurethane membranes with islets of Langerhans. Studies indicate that polyurethane membranes T4 and T5 could be potential candidates for islet immunoisolation.     

Antibacterial nanohydroxyapatite/polyurethane composite scaffolds with silver phosphate particles for bone regeneration

Solving the issue of infection associated with implanted bone substitutes is one of the modern challenges of the biomedical engineering field. The purpose of this study was to develop a novel porous scaffold with sufficient antibacterial activity for bone repair or regeneration. Porous nanohydroxyapatite/polyurethane (n-HA/PU) composite scaffolds containing different amounts of silver phosphate particles were prepared through the in situ foaming method. Subsequently, their physicochemical properties, antibacterial abilities, and preliminary cytocompatibilities were evaluated. The results indicated that the porosity and mechanical properties of the n-HA/PU scaffolds incorporated with Ag₃PO₄ did not change significantly compared to n-HA/PU scaffold without Ag₃PO₄. The release of Ag⁺ was time and concentration dependent, increasing with the immersion time and Ag₃PO₄ percentage in the scaffolds. A continuous Ag⁺ release can last more than 3 weeks. The antibacterial tests and cytocompatibility evaluation revealed that n-HA/PU scaffolds with 3 wt% Ag₃PO₄ (n-HA/PU3) exhibit stronger antimicrobial effects as well as satisfactory cytocompatibility. The n-HA/PU3 scaffolds may hold great potential for application in the field of bone regeneration, especially for infection-associated bone defect repair.     

Surface and hemocompatibility studies of bi-soft segment polyurethane membranes

Cross-linked urethane/urea membranes with two soft segments were prepared by extending a poly(propylene oxide) based tri-isocyanate-terminated prepolymer (PUR) with polybutadiene diol (PBDO). The ratio of prepolymer and polybutadiene diol was varied to yield cross-linked membranes with different compositions, exhibiting different degrees of phase-separation of the PBDO segments in the bulk and of surface enrichment in PUR. In this work, surface energy and hemocompatibility aspects (hemolysis and thrombosis) of the PUR/PBDO membranes were evaluated. The results showed that the membrane surface energy increased with the PBDO content until 25% of PBDO, and decreased thereafter. The introduction of the second, more hydrophobic, soft segment (PBDO) in the PUR membranes turned hemolytic into non-hemolytic membranes and, for a blood-material contact time of 10 minutes, decreased the thrombogenicity significantly. The 10% PBDO membrane was the least thrombogenic and was also non-hemolytic. The hemolysis degree did not vary significantly with the PBDO content while, for blood-material contact times of 10 minutes, the thrombogenicity increased with an increase in PBDO content above 10%. Membrane thrombogenicity varied with the blood-material contact time. For blood contact times of 10 minutes, all membranes tested were less thrombogenic than glass.     

Preparation and characterization of alpha-amylase-immobilized thermal-responsive composite hydrogel membranes.

Composite hydrogel membranes of crosslinked poly(N-isopropylacrylamide-co-N-acryloxysuccinimide-co-2-hydroxyet hyl methacrylate) [P(NIPAAm-NAS-HEMA)] with starch, as a macropore forming agent, on nonwoven polyester was prepared. The membranes could swell and de-swell around the characteristic lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAAm). It was demonstrated that the presence of macropores in the membranes could improve the immobilization efficiency as well as lead to a short responding time upon temperature change across the LCST. Immobilized alpha-amylase could retain as high as 33% of the activity of the free enzyme with a loading level of 0.60-0.65 mg/cm2 when the membrane preparation and enzyme immobilization conditions were optimized. The half time (T0.5) for the swelling or de-swelling response of the gel phase within the membranes was less than 2 min, and the 90% time (T0.9) was less than 6 min. The permeability for maltose through the membranes could change as much as 4.9-fold when the temperature was raised above or reduced below the LCST.     

Cell separation of hepatocytes and fibroblasts through surface-modified polyurethane membranes

The separation of fibroblast cells (L929 cells) and hepatocytes was investigated by using unmodified and surface-modified polyurethane (PU) foaming membranes (pore size of 12 microm) by the incorporation of various functional groups. L929 cells permeated more readily than hepatocytes, and very few populations of hepatocytes (<5%) permeated through the membranes. This result was thought to be due to the smaller cell size of the L929 cells (5-10 microm) relative to the hepatocytes (15-30 microm). The larger hepatocytes were thought to plug the pores of the membranes. A good cell separation between L929 cells and hepatocytes was achieved when the cell mixture permeated through the negatively charged PU membranes. The negatively charged membranes were thought to enhance the permeation of L929 cells because of the electrostatic repulsion between the membranes and negatively charged cells. On the other hand, the hepatocytes were unable to permeate through the membranes because of the sieve effect caused by their large cell size. The separation of hepatocytes isolated from mice at different ages was also accomplished by permeating the cell mixture through unmodified and surface-modified PU membranes.     

Chitosan/nanohydroxyapatite composite membranes via dynamic filtration for guided bone regeneration

Chitosan/hydroxyapatite (HA) composite membranes were prepared by the coprecipitation method and a subsequent dynamic filtration and freeze-drying process. The influences of the HA content of the membranes on their phase and morphology, mechanical properties, and bioactivity were investigated. FTIR analysis revealed that chitosan and HA had good miscibility over a wide range of compositions. Needle-like HA nanocrystals with low crystallinity were uniformly embedded in the chitosan matrix. As the HA content was increased, the tensile strength of the membranes exhibited a steady decrease, while the elastic modulus increased by a factor of 2 when 20% HA was added. The results of the in vitro cell culture showed that the highest alkaline phosphatase level was achieved when 30% HA was contained in the composites.     

Anion permeation behavior of polypyrrole/regenerated cellulose composite membranes under applied potential

Composite membranes were prepared by combination of polypyrrole and a porous material of regenerated cellulose, and the permeation characteristics of a variety of anion species through the composite membranes were investigated under different potentials applied. The composite membranes work effectively as a functional membrane to control the permeation flux of anions by application of a potential. The anion permeation flux increases constantly as the potential is raised, except for the anions with extremely low molecular weight. This is explained by a permeation model in which the ion-exchanging migration of the anions through the positive sites of the polypyrrole layer contributes largely to their permeation. The main factors dominating the permeation characteristics are the molecular weight of the anions and the morphology of the polypyrrole layer. Permselectivity, i. e., separation of specific anions with a certain molecular weight, is expected for the composite membranes.     

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.