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ABSTRACT: A small-diameter vascular graft (inner diameter 4 mm) was fabricated from polyurethane (PU) and poly(ethylene glycol) (PEG) solutions by electrospinning technology. The fiber diameter decreased from 1023 +/-185 nm to 394 +/- 106 nm with increasing weight ratio of PEG in electrospinning solutions. The PU/PEG scaffolds showed randomly nanofibrous morphology and well-interconnected porous structure. The hydrophilicity of these scaffolds was improved significantly with increasing weight ratio of PEG. The mechanical properties of electrospun PU/PEG scaffolds were obviously different from that of pure PU scaffold, which was caused by plasticizing or hardening effect imparted by PEG composition. Under hydrated state, the PU/PEG scaffolds demonstrated low mechanical performance due to the hydrophilic property of materials. Compared with dry PU/PEG scaffolds with the same weight ratio of PEG, the tensile strength and elastic modulus of hydrated PU/PEG scaffolds decreased significantly, while the elongation at break increased. The results demonstrated that the electrospun PU/PEG hybrid tubular scaffolds are potential candidates for artificial blood vessels.
Journal of Nanoscience and Nanotechnology 02/2013; 13(2):1578-82. · 1.56 Impact Factor
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ABSTRACT: Poly(ethylene glycol) monoacrylates (PEGMAs) with a molecular weight between 400 and 1,000 g mol(-1) were grafted by ultraviolet initiated photopolymerization on the surface of polycarbonateurethane (PCU) for increasing its hydrophilicity and improving its hemocompatibility. The surface-grafted PCU films were characterized by Fourier transformation infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle, scanning electron microscopy (SEM) and atomic force microscopy measurements. The surface properties of the modified films were studied in dry and wetted state. Blood compatibility of the surfaces was evaluated by platelet adhesion tests and adhered platelets were determined by SEM. The results showed that the hydrophilicity of the films had been increased significantly by grafting PEGMAs, and platelets adhesion onto the film surface was obviously suppressed. Furthermore, the molecular weight of PEGMAs had a great effect on the hydrophilicity and hemocompatibility of the PCU films after surface modification and increased with increasing molecular weight of PEGMAs.
Journal of Materials Science Materials in Medicine 06/2012; · 2.32 Impact Factor
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ABSTRACT: In this paper, a scaffold, which mimics the morphology and mechanical properties of a native blood vessel is reported. The
scaffold was prepared by sequential bi-layer electrospinning on a rotating mandrel-type collector. The tubular scaffolds (inner
diameter 4 mm, length 3 cm) are composed of a polyurethane (PU) fibrous outer-layer and a gelatin-heparin fibrous inner-layer.
They were fabricated by electrospinning technology, which enables control of the composition, structure, and mechanical properties
of the scaffolds. The microstructure, fiber morphology and mechanical properties of the scaffolds were examined by means of
scanning electron microscopy (SEM) and tensile tests. The PU/gelatinheparin tubular scaffolds have a porous structure. The
scaffolds achieved a breaking strength (3.7±0.13 MPa) and an elongation at break (110±8%) that are appropriate for artificial
blood vessels. When the scaffolds were immersed in water for 1 h, the breaking strength decreased slightly to 2.2±0.3 MPa,
but the elongation at break increased to 145±21%. In platelet adhesion tests the gelatin-heparin fibrous scaffolds showed
a significant suppression of platelet adhesion. Heparin was released from the scaffolds at a fairly uniform rate during the
period of 2nd day to 9th day. The scaffolds are expected to mimic the complex matrix structure of native arteries, and to have good biocompatibility
as an artificial blood vessel owing to the heparin release.
Keywordselectrospinning–artificial blood vessels–scaffold–polyurethane–gelatin–nanofiber–hemocompatibility
05/2012; 5(3):392-400.
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ABSTRACT: Polycarbonate urethane (PCU) nano-fibers were fabricated via electrospinning using N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) as the mixed solvent. The effect of volume ratios of DMF and THF in the
mixed solvent on the fiber structures was investigated. The results show that nano-fibers with a narrow diameter distribution
and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1:1. When the proportion
of DMF was more than 75%in the mixed solvent, it was easy to form many beaded fibers. The applied voltage in the electrospinning
process has a significant influence on the morphology of fibers. When the electric voltage was set between 22 and 32 kV, the
average diameters of the fibers were found between 420 and 570 nm. Scanning electron microscopy (SEM) images showed that fiber
diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration.
When the concentration of PCU solution was 6.0 wt-%, a beaded-fiber microstructure was obtained. With increasing the concentration
of PCU solutions above 6.0 wt-%, beaded fiber decreased and finally disappeared. However, when the PCU concentration was over
14.0 wt-%, the average diameter of fibers became large, closed to 2 μm, because of the high solution viscosity. The average
diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution (10.0 wt-%)when the applied
voltage was 24 kV. The results show that the morphology of PCU fibers could be controlled by electrospinning parameters, such
as solution concentration, electric voltage and flow rate.
Keywordselectrospinning–polycarbonate urethane–process parameter–average diameter–morphology
04/2012; 5(1):11-18.
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ABSTRACT: Thrombus formation and blood coagulation are serious problems associated with blood contacting products, such as catheters,
vascular grafts, artificial hearts, and heart valves. Recent progresses and strategies to improve the hemocompatibility of
biomaterials by surface modification using photochemical immobilization and photograft polymerization are reviewed in this
paper. Three approaches to modify biomaterial surfaces for improving the hemocompatibility, i.e., bioinert surfaces, immobilization
of anticoagulative substances and biomimetic surfaces, are introduced. The biomimetic amphiphilic phosphorylcholine and Arg-Gly-Asp
(RGD) sequence are the most effective and most often employed biomolecules and peptide sequence for improving hemocompatibility
of material surfaces. The RGD sequence can enhance adhesion and growth of endothelial cells (ECs) on material surfaces and
increase the retention of ECs under flow shear stress conditions. This surface modification is a promising strategy for biomaterials
especially for cardiovascular grafts and functional tissue engineered blood vessels.
Keywordsanticoagulative-biomimetic-biomaterials-hemocompatibility-phosphorylcholine-photochemical immobilization-photograft polymerization-photolinker-surface modification
Frontiers of Chemical Engineering in China 04/2012; 4(3):372-381.
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01/2012: pages 171-176;
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Journal of Controlled Release 11/2011; 152 Suppl 1:e202-4. · 5.73 Impact Factor
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Journal of Controlled Release 11/2011; 152 Suppl 1:e21-3. · 5.73 Impact Factor
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Journal of Controlled Release 11/2011; 152 Suppl 1:e28-9. · 5.73 Impact Factor
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Journal of Controlled Release 11/2011; 152 Suppl 1:e20-1. · 5.73 Impact Factor
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ABSTRACT: Nitric oxide (NO) is a well known potent antiplatelet agent, and its continuous release will effectively prevent the adhesion of platelets on artificial blood vessel walls. In this paper, polycarbonateurethane (PCU) with lipophilic Cu(II)-complex (Cu(II)-DTTCT) blending films were prepared and used as catalyst to generate NO from nitrite. The mechanical properties of PCU films blended with Cu(II)-DTTCT were characterized by tensile strength measurement. The tensile stress and Young's modulus of PCU films blending with Cu(II)-DTTCT increased, however, the elongation at break decreased compared with corresponding PCU films. The NO generation was investigated in vitro in the presence of NaNO2 and ascorbic acid in PBS (pH = 7.4) at 37°C. The flux of NO generation was quantitatively measured by Griess assay. NO flux and velocity increased with the increase of NaNO2 concentration, the concentration of ascorbic acid in PBS and the amount of Cu(II) in the films. The loss of Cu(II) from blending film surfaces was found during the in vitro NO generation experiments, which resulted in the decrease of NO flux in the second run. The PCU film could catalyze continually generation of NO for two days, which will provide a promising approach that enable endogenous NO generation on the surface of the medical devices. The generation of biologically active level of NO at the blood/polymer interface can reduce the risk of thrombosis on the implants. Polycarbonateurethane films with NO generation function may be used as high thromboresistant blood contacting materials or coating. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Applied Polymer Science 05/2011; 122(3):1712 - 1721. · 1.29 Impact Factor
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ABSTRACT: The novel hydrophilic sulfoammonium zwitterionic polyethylene glycol (SAPEG) macromolecule was designed and synthesized using polyethylene glycol (PEG, Mw = 1000) as the starting agent. The sulfoammonium zwitterionic PEG was grafted onto polycarbonate urethane (PCU) via two ways: (1) direct grafting of SAPEG onto PCU using diisocyanate as a spacer; (2) grafting of PEG mono(N,N-dimethyl glycine)ester (APEG) onto the PCU with diisocyanate, and then reacting with 1,3-propanesulfone via ring-opening reaction to form sulfoammonium zwitterionic structure. The X-ray photoelectron spectroscopy (XPS) was used to analyze the elements of the grafted materials. The results showed that the sulfur contents on the modified PCU were 0.5 and 0.9% for both grafting methods, respectively, indicating sulfoammonium zwitterionic PEG has successfully been grafted onto PCU chains. The low-water contact angle showed that the modified PCUs were higher hydrophilic than unmodified PCU. The results of hemolysis test and cytotoxicity test indicated that blood compatibility of the modified PCU was better than that of the unmodified PCU. The modified PCUs are preferred candidates for blood-contacting implants or devices due to the hemocompatibility and nontoxicity in vitro. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Applied Polymer Science 05/2011; 122(2):1084 - 1091. · 1.29 Impact Factor
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ABSTRACT: In this study, we used a UV radiation grafting method to modify the surface of the biomaterial polycarbonateurethane (PCU). Hydrophilic poly(ethylene glycol) monoacrylate (PEGMA; number-average molecular weight = 526) as a macromolecular monomer was grafted onto the PCU surface by UV photopolymerization. The Fourier transform infrared and X-ray photoelectron spectroscopy results of the graft-modified PCU confirmed poly[poly(ethylene glycol) monoacrylate] block grafting onto the surface. We investigated the effects of the reaction temperature, macromolecular monomer concentration, UV irradiation time, and photoinitiator concentration on the grafting density (GD) in detail. Furthermore, we investigated the effects of GD under various process conditions on the water uptake and water contact angle. The modified materials had a high water uptake and low water contact angle, which indicated that the hydrophilicity of the PCU surface was improved significantly by the introduction of the hydrophilic poly(ethylene glycol) blocks on the surface. The anticoagulant properties of the material might also have been improved. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Applied Polymer Science 10/2010; 119(6):3717 - 3727. · 1.29 Impact Factor
