Biocompatibility of poly(carbonate urethane)s with various degrees of nanophase separation

Nanophase separation has been suggested to influence the biological performance of polyurethane. In a previous work, six different 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethane)s (PCUs) that exhibited various degrees of nanophase separation were synthesized and characterized. In the present work, these PCUs were used as a model system to study the effect of nanometric structures on the biocompatibility of polyurethane. Human blood platelet activation, monocyte activation, protein adsorption, and bacterial adhesion on PCU were investigated in vitro. It was found that human blood platelets as well as monocytes were less activated on the PCU surfaces with a greater degree of nanophase separation in general. This phenomenon was closely associated with the lower ratio of human fibrinogen/albumin competitively adsorbed on these surfaces. Bacterial adhesion was also inhibited in some nanophase-separated PCUs. [diagram in text].     

Amphiphilic segmented polyurethanes as surface modifying additives

Amphiphilic segmented polyetherurethanes were prepared from methylene diphenylene diisocyanate (MDI), poly(ethylene glycol) 1500 (PEG), and a fatty acid monoglyceride as a chain extender. The polymers were not soluble in water or methanol, but dissolved readily in organic solvents. The amphiphilic properties were demonstrated as a large hysteresis in the water contact angles, exceeding 110°. The amphiphilic polymers were shown to modify the surface properties of a poly(ether urethane) (PEU) and a poly(ether urethane urea) (PEUU) when added in 1–10 wt %, presumably due to migration of the additive to the surface. The surfaces of particularly the PEU blends became highly amphiphilic, exhibiting contact angles hystereses up to 90–100°. A surface saturation effect was observed at 5% added amphiphilic polymer. A difference in the behavior of PEU and PEUU was ascribed to differences in solubility of the additive in the matrix. On long-term exposure to water the PEUU blends increased their amphiphilic behavior.     

RGD改性聚醚氨酯及其内皮细胞相容性的研究

利用氢键稳定的溶液互穿技术对聚醚氨酯(PEU)进行改性.用ATR-FTIR对十八烷基-聚氧乙烯-4,4'-二苯甲烷二异氰酸酯-聚氧乙烯-十八烷基(MSPEO)与PEU共混膜表面进行研究,结果表明,MS-PEO中的氨基甲酸酯链段与PEU基材之间发生了氢键缔合的作用.通过水化处理PEO及十八烷基自发地富集在基材表面.根据氢键缔合和表面自迁移原理,设计了两种RGD改性聚醚氨酯的方法:(1)将含RGD端基的聚氧乙烯-4,4'-二苯甲烷二异氰酸酯-聚氧乙烯偶联物(MPEO-RGD)与PEU进行共混改性,利用RGD端基及PEO的自迁移特性获得RGD富集的表面;(2)将含甲磺酸酯端基的聚氧乙烯-4,4'-二苯甲烷二异氰酸酯-聚氧乙烯偶联物(MPEO-mesyl)与PEU共混成膜,并对膜片进行水化处理,使甲磺酸酯端基富集在PEU表面,浸泡于RGD的PBS溶液中,在膜片表面成功地原位接枝了RGD.对两种RGD改性方法获得的表面进行了内皮细胞的培养,结果表明,两种改性方法均大大提高了PEU的细胞相容性,其中方法(1)共混改性的表面细胞相容性略优于方法(2)的接枝改性表面.     

LARGELY IMPROVED BLOOD COMPATIBILITY OF POLYURETHANE BY BLENDING WITH FLUORINATED PHOSPHATIDYLCHOLINE POLYURETHANE

The improvement of biocompatibility of polyurethanes was investigated.The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatidylcholine poly(carbonate urethane)s(FPCPCUs).The solution blending was done by mixing poly(ether urethane)(PEU)with FPCPCU in different compositions.An increased blood compatibility of the blend films was observed with the increase of FPCPCU content,and when FPCPCU content reached to 40 wt%(...     

Biocompatibility and biostability of a series of poly(carbonate)urethanes

In this work, we synthesized several MDI-based poly(carbonate)urethanes (PCU) by using four different soft segments, including two aliphatic macrodiols (poly(hexyl, ethyl)carbonate diols, MW 2017 and 865, respectively) and two aromatic macrodiols (MW approximately 2000 and 1000, respectively), in different molar ratios to MDI. We demonstrate that these polymers exhibited various degree of micro-phase separation that further influenced their surface protein adsorption, platelet activation as well as cellular attachment and growth. Polyurethanes based on poly(hexyl, ethyl)carbonate diol with MW 2017 in a molar ratio MDI/macrodiol/chain extender of either 3/2/1 or 4/3/1 resulted in greater micro-phase separation as well as superior biocompatibility and biostability.     

New fluorinated oxazoline block copolymer lowers the adhesion of platelets on polyurethane surfaces

We have prepared an amphiphilic oxazoline block copolymer of hydrophilic poly(2-methyl-2-oxazoline) and hydrophobic poly[2-(2-perfluorooctyl)ethyl-2-oxazoline] chains. By controlling the length and composition of polymer chains, we found that this fluorinated block copolymer can be readily dissolved in water. Furthermore, we can achieve a stable surface coating of the fluorinated block copolymer by dissolving the copolymer in water, then coating the aqueous copolymer solution onto surfaces of nonwater-soluble polymers. This is a simple and useful method of modifying the surface character of polymer substrates. We have found that the polyether urethane (PEU) coated by block copolymer has a different surface chemistry and biological reactivity than the uncoated PEU. From XPS analysis, we found the fluorinated copolymer was coated on PEU (atomic % of F: 31.3 on coated PEU, 0.3 on uncoated). The two surfaces have different affinities for biological molecules. Specifically, the fibrinogen adsorption on the fluorinated copolymer-coated PEU was 62 ± 39 ng/cm², compared to a value of 156 ± 99 ng/cm² for uncoated PEU. In an ex vivo evaluation of platelet adhesion, the surface of coated PEU attached a few white cells while uncoated PEU was covered with activated platelets. © 1994 John Wiley & Sons, Inc.     

Novel silver/polyurethane nanocomposite by in situ reduction: Effects of the silver nanoparticles on phase and viscoelastic behavior

A novel silver/poly(carbonate urethane) nanocomposite was prepared through in situ reduction of a silver salt (AgNO₃) added to a solution consisting of a commercial poly(carbonate urethane) dissolved in N,N‐dimethylformamide (DMF). In this system, the presence of the poly(carbonate urethane) was proved to protect the silver nanoparticles, whose formation was confirmed by means of UV–vis spectroscopy, from aggregation phenomena. The silver morphology developed in the solid state after DMF casting was imaged by FESEM. Homogeneous dispersion of silver nanoprisms in the poly(carbonate urethane) matrix was clearly observed. The effects of dispersion of silver nanoparticles within the poly(carbonate urethane) matrix were investigated by means of ATR‐FTIR and multifrequency dynamic mechanical thermal analyses. The obtained results revealed that the presence of silver nanoparticles modifies both the phase and the viscoelastic behaviors of poly(carbonate urethane). As a matter of fact, the hydrogen bond formation in the hard and soft segments was found to be hindered and the molecular motions of the soft segments were restricted, because a comparatively higher activation energy was required for the related α‐relaxation process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 344–350, 2008     

Cell attachment and proliferation on poly(carbonate urethanes) with various degrees of nanophase separation

In this work, we synthesized six 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethanes) (PCU) by using the macrodiol poly(1,6-hexyl, 1,2-ethyl carbonate) diol (MW = 2,017) in different molar ratios to MDI. The bulk and surface properties of cast PCU films were analyzed. The glass transition temperatures measured by dynamic mechanical analysis (DMA) and surface images obtained from atomic force microscopy (AFM) indicated that these PCU had various degrees of nanophase separation that changed with the time and film casting temperatures. The degree of nanophase separation correlated very well with endothelial cell attachment and proliferation on PCU.     

Synthesis and properties of cationic ionomers from poly(ester‐urethane)s based on polylactide

l ‐Lactide (l ‐LA) was polymerized in the presence of N‐methyldiethanolamine as an initiator and Sn(Oct)₂ as a catalyst to give hydroxy‐telechelic poly(l ‐lactide) (PLLA‐diol) bearing a tertiary amine group at the center of the polymer chain. Successive chain extension of the PLLA‐diol with hexamethylene diisocyanate afforded PLLA‐based poly(ester‐urethane)s (PEU) with equally spaced tertiary amine groups. Treatment of the PEU with iodomethane converted tertiary amine groups to quaternary ammonium groups to give cationic ionomers (PEU‐MeI). The thermal, mechanical, hydrophilic, and biodegradation properties of the obtained polymers were investigated. The thermal properties of the PEUs and the PEU‐MeIs were similar each other. The PEU‐MeIs exhibited higher tensile modulus than those of the starting PEUs. The contact angles of water on the PEU‐MeIs were lower than those of the PEUs with similar NMDA content indicating their higher hydrophilicity. In compost degradation tests, the PEU‐MeIs showed slower degradation than those of the PEUs. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4423–4428     

铈盐引发聚醚氨酯膜上丙烯酰胺接枝聚合反应

由聚四亚甲基醚二醇、4,4′-二苯基甲烷二异氰酸酯与乙二胺或丁二醇扩链剂合成的聚醚氨酯薄膜,可顺利地在室温下用硝酸铈铵引发接枝丙烯酰胺共聚合反应,这可以从反应后的薄膜由起始时是透明的而变为不透明,也可以从接枝后的薄膜比基膜有较大的吸水率,以及从扫描电子显微镜观察到薄膜表面上有凸起图象的高分子链所证实,由于先发生接枝共聚合而后才是均聚反应,因而保证了接枝后的薄膜几乎不附着聚丙烯酰胺。     

HDI作为扩链剂合成含PLLA和PBS链段的聚酯氨酯

以数均分子量为6350g/mol端羟基聚L-乳酸(PLLA-OH)与10500g/mol端羟基聚丁二酸丁二酯(PBS-OH)为预聚物,六亚甲基二异氰酸酯(HDI)为扩链剂,通过熔融反应制备了分子量高达30×104g/mol的可完全生物降解聚酯氨酯(PEU).研究了异氰酸根(NCO)与羟基比例对扩链反应的影响.结果表明,当[NCO]/[OH]=1∶1时,扩链效果最好,PEU分子量最大;PEU分子量随着预聚物中PBS含量增大而提高.通过核磁共振谱(1H-NMR)确定了PEU的结构与组成,并对聚酯氨酯进行了凝胶渗透色谱(GPC)、差示扫描量热(DSC)、热重分析(TGA)以及拉伸性能测试.DSC结果显示,扩链后PEU的结晶主要由PBS链段产生,而PLLA链段几乎不结晶;TGA结果表明,PEU的热降解分两步进行,第一步为PEU中PLLA链段的热降解,第二段为其中PBS链段的降解;拉伸测试结果表明,PBS与PLLA的共聚能够制备拉伸强度与断裂伸长率优异的聚合物材料.     

Degradation of poly(carbonate urethane) by gamma irradiation

Poly(carbonate urethane) (PCU), is a valuable commercial engineering polymer. In order to understand the possible use of PCU in radioactive waste management as a solidifying agent or as a disposal container, radiation stability of the PCU is studied by Co-60 gamma irradiations at two different dose rates of 1540 and 82.8 Gy/h. The total dose of irradiation was up to 6.24 MGy. Degradation nature was tested by studying the changes in mechanical and thermal properties with rate and total dose of irradiation. Ultimate tensile strength and toughness first increased and then decreased with the irradiation dose. Half value dose (HVD) for elongation was 4010 kGy and for tensile strength 6010 kGy at the dose rate of 1540 Gy/h. The non-irradiated PCU transparent color changed to yellow and then brown with increased irradiation dose. The FTIR spectral analysis showed a random scission of polymer with irradiation. From the experimental observation, it was shown that PCU can be used for embedding radioactive waste for about 300 years.     

Synthesis and properties of poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties

Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate‐urethane). The hydrolysis and thermal behaviors of poly(HC‐MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND‐MDI)) prepared from MDI and 1,9‐nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC‐MDI) is less crystalline than poly(ND‐MDI). Poly(HC‐MDI) is more susceptible to hydrolysis than poly(ND‐MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802–2808, 2006     

Monitoring protein distributions based on patterns generated by protein adsorption behavior in a microfluidic channel

We report a unique monitoring technique of protein distributions based on distinctive patterns generated by protein adsorption behavior on a solid surface in a microfluidic channel. Bare gold and COOH-modified self-assembled monolayer (SAM) sensing surfaces were pre-adsorbed with one of four different proteins: lysozyme, albumin, transferrin, or IgG. Each surface provides a thermodynamically governed platform for immobilizing proteins and generates analyte-specific response patterns. Each surface has its own thermodynamic energy governing pre-adsorbed protein behaviors, so that sample proteins react with the pre-adsorbed ones to different extents depending on their sizes, isoelectric points (pI), and characteristics of the sensing surfaces. Modified surfaces were mounted and monitored in real time using surface plasmon resonance (SPR). Buffer-prepared sample matrices (α1-antitrypsin, haptoglobin, C-reactive protein (CRP), and IgM) characterized protein response patterns. Each surface generated distinctive patterns based on individual SPR angle shifts. We classified each sample with 95% accuracy using linear discriminant analysis (LDA). Our method also discriminated between different concentrations of CRP in the cocktail sample, detecting concentrations as low as 1 nM with 91.7% accuracy. This technique may be integrated with a microfluidic lab-on-a-chip system and monitor the distribution of a specific group of proteins in human serum.     

Surface modification of polycarbonate urethane by grafting polyethylene glycol and bivalirudin drug for improving hemocompatibility

As the clinical demand for blood-contacting materials increases, higher requirements are placed on their physicochemical properties, durability and hemocompatibility in vivo. In this work, a multiple functionalized material was developed through a facile modification process. Herein, polycarbonate urethane (PCU) surface was co-modified with polyethylene glycol (PEG) and bivalirudin (BVLD). PCU provides excellent physical and mechanical properties, PEG and BVLD, especially BVLD, enable the surface with outstanding anticoagulant capacity. Specifically, PCU surface was first treated with hexamethylene diisocyanate to introduce active isocyanate groups onto the surface, followed by hydroxy-PEG grafting to improve the hydrophilicity. Finally, BVLD was immobilized on the surface via Michael addition reaction to improve antithrombotic properties. Attenuated total reflection Fourier transforms infrared spectroscopy and UV spectrophotometers were used to confirm the modified surfaces. The hydrophilicity was characterized by static water contact angle measurement, the morphology of the modified surfaces was observed by scanning electron microscopy. Blood compatibility of the modified surfaces was characterized by the hemolysis rate, platelet adhesion assay and cell culture test. The results showed that the BVLD immobilized surface has excellent anticoagulant properties, good fibrin-bound thrombin inhibition, and good resistance against non-specific adhesion of proteins. Hence, the co-modification with PEG and BVLD was proved an encouraging strategy for improving hemocompatibility.     

Swelling of interpenetrating polymer networks

We have studied the densities, kinetics, and equilibrium degree of swelling in a number of different solvents of poly(carbonate urethane)/poly(methyl methacrylate) and poly(carbonate urethane)/poly(vinyl pyridine) interpenetrating polymer networks (IPN's). The kinetics of solvent uptake are often anomalous. The equilibrium extent of swelling reflects, among other factors, the number of phases present. © 1993 John Wiley & Sons, Inc.     

A multitechnique surface analytical study of a segmented block copolymer poly(ether-urethane) modified through an H2O radio frequency glow discharge

Recent work in our laboratories has fully characterized the surface region of a segmented poly(ether-urethane) (PEU) extending from the air/polymer interfacial region through bulk depths in the micron range. This characterization utilized energy and angle dependent Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR–FTIR), and Comprehensive Wettability Profiling (contact angle using a homologous series of liquids) as defined by Zisman. In this study this same multi-analytical-technique approach is used to elucidate changes in these PEU surfaces induced through an H₂O Radio Frequency Glow Discharge (RFGD) plasma. This investigation reports both qualitative and quantitative changes due to the modification treatments as well as the permanency of the changes effected on these surfaces through the plasma treatment. From our analyses, the amount of surface residing polyurethane (hard segment) is observed to increase due to a proposed plasma etching mechanism. Further, the addition of oxygen containing functionality is detected at the modified surfaces unique with respect to the unmodified PEU. These surface modifications which show large increases in wettability, are finally observed to be semi-permanent over a time period of 6 months.     

Surface modification and characterization of microfabricated poly(carbonate) devices: manipulation of electroosmotic flow

Poly(carbonate), PC, surfaces are chemically modified by treatment with sulfur trioxide gas. Sulfur trioxide gas sulfonates the aromatic rings of the poly(carbonate) surfaces, making the surfaces more hydrophilic. Sulfonation of the poly(carbonate) surface is confirmed by infrared spectroscopy. The modified polymer surfaces are found to be smoother in comparison to their unmodified counterparts, as noted by scanning force microscopy. The effects of the surface modification on electroosmotic flow are studied at a pH range of 4-10. The electroosmotic flow in sulfonated poly(carbonate) microchannels was found to be significantly higher than that in unmodified poly(carbonate) microchannels at pH values below 8.     

Thermal Properties and Morphology of Poly(Ester-Urethanes) Prepared from Polycaprolactone-Diol

The soft segment crystallinity and morphology of poly(ester-urethanes) (PEUs) based on poly(ε-caprolactone) (PCL) as a soft segment and an aliphatic diisocyanate in the hard segment were studied. It was found that the restriction of the crystallization of the PCL soft segment depends on the hard segment concentration, the length of the soft segment, and the total molecular mass of the PEUs. The PEU based on a low molecular mass PCL (M=2000) is an amorphous elastic material during a long time after casting from solution or after melt crystallization. A soft-hard segment endothermal mixing transition (T_mix) of about 70-80°C is observed in the DSC curves of this PEU sample. This revised version was published online in August 2006 with corrections to the Cover Date.     

Fibronectin adsorption on titanium surfaces and its effect on osteoblast precursor cell attachment

The objective of this study was to investigate the adsorption of fibronectin on titanium (Ti) surfaces and the effect of pre-adsorbed fibronectin on osteoblast precursor cell attachment in vitro. Two different concentrations of bovine fibronectin were used in this study. Protein adsorption on Ti surfaces was analyzed using the micro bicinchoninic acid (BCA) protein assay. Cell concentration on Ti and fibronectin pre-adsorbed Ti surfaces after 3 h incubation was analyzed using the Vybrant™ cell adhesion assay. Cell morphology on Ti and fibronectin pre-adsorbed Ti surfaces was observed using scanning electron microscopy (SEM). After 180 min incubation, maximum adsorption of bovine fibronectin on Ti surfaces was observed. Fibronectin adsorption on Ti surfaces was observed to be significantly dependent on the initial concentration and the amount of incubation time. In the presence of 1 mg/ml fibronectin pre-adsorbed on Ti surfaces after 15 min, osteoblast precursor cell attachment on Ti surfaces was observed to be enhanced compared with control Ti surfaces, Ti surfaces pre-adsorbed with 1 mg/ml fibronectin for 180 min, and Ti surfaces pre-adsorbed with 0.1 mg/ml fibronectin for 15 and 180 min. No significant difference in cell attachment was observed between control Ti surfaces, Ti surfaces pre-adsorbed with fibronectin for 180 min, and Ti surfaces pre-adsorbed with 0.1 mg/ml fibronectin for 15 and 180 min. In addition, no differences in cell morphology of the attached osteoblast precursor cells on control Ti surfaces and Ti surfaces pre-adsorbed with fibronectin were observed in this study. It was concluded that an optimum concentration of adsorbed fibronectin on Ti surfaces plays an important role in governing cell attachment.