Anticoagulant Activity of Immobilized Heparin on the Polypropylene Nonwoven Fabric Surface Depending upon the pH of Processing Environment (original) (raw)
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Cardiopulmonary surgeries need connectors for extracorporeal circulation. The patient's blood in contact with the tube surfaces modifies its plasmatic proteins, promotes platelet aggregation, and activates the complement system, unleashing thrombus formation. Thus, it becomes necessary for an anticoagulant to keep the circuit free from these events. Heparin is the anticoagulant used even after reports about its disadvantages. Platelet adherence seems to be very dependent on the quality from the surfaces that can promote cellular proliferation, aggregation, and
Journal of Biomedical Materials Research Part A, 2005
We have applied an in vitro perfusion model to explore the potential thrombogenicity of polyester annulolasty fabric used in valve repair and to investigate the possible thromboresistance characteristics conferred by a special heparin coating (Duraflo™ treatment). Samples of human blood from i) untreated or ii) heparin-coated extracorporeal circuits were recirculated through annular perfusion chambers containing a) untreated or b) treated annuloplasty cloth material. Perfusion experiments were performed at a shear rate of 600 s Ϫ1 for 20 min. Platelet interaction with the material was morphometrically evaluated. In experiments performed with blood from untreated circuits and cloth material, the average crosssectional area of platelet mass was 615 Ϯ 135 m 2 . Treatment of cloth material with Duraflo™ statistically decreased the area of interacting platelets to 319 Ϯ 101 m 2 (*p Ͻ 0.05, n ϭ 10). Blood samples from heparin-coated extracorporeal circuits showed a decrease of total area of platelets (308 Ϯ 58 m 2 vs 138 Ϯ 30 m 2 , *p Ͻ 0.05, n ϭ 9). The combined treatment of Duraflo™ in extracorporeal circuits and cloth material caused a more consistent reduction (p Ͻ 0.05). The in vitro perfusion experimental model was sensitive to evaluate the thrombogenic potential of Duraflo™ treatment. Our results indicate that the heparin coating of cloth material and extracorporeal circuits improves the biocompatibility of the original material and reduces the thrombogenic profile.
The Effects of Heparin Coating of Oxygenator Fibers on Platelet Adhesion and Protein Adsorption
Anesthesia & Analgesia, 1999
Platelet adhesion on the cardiopulmonary bypass oxygenator membrane is associated with impaired hemostasis. We investigated the effects of heparin coating of the oxygenator membrane on protein adsorption and platelet adhesion on the surface. Noncoated and heparin-coated polypropylene membranes were incubated in whole blood with small-(1 U/mL) or large-dose (5 U/mL) heparin as an anticoagulant for 3 h at 37°C. The amount of platelets adhering on each fiber was assessed by using enzyme immunoassays using monoclonal antibodies directed against CD42b (GP Ib) and CD61 (GP IIb/IIIa). Platelet activation was assessed by measuring plasma guanosine monophosphate 140 levels. The amount and composition of the adsorbed proteins on the surface were analyzed by using a bicinchoninic acid protein assay and by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting technique. The heparin
MRS Proceedings, 2012
ABSTRACTPolymeric materials have been attracted the attention of researchers in various R&D applications. In this research, attempts were made to evaluate the changes in blood compatibility of polyethylene terephthalate (PET) by grafting acrylic acid (AAc) and immobilizing heparin by employing two-step plasma treatment. The PET surface was modified by using a novel method named “two-step plasma treatments” (TSPT). While first plasma is creating active sites for grafting, the second plasma polymerizing pre-adsorbed reactive monomer onto the surface of films. Finally, heparin immobilization was performed in the presence of 1-ethyl-3-(dimethylaminopropyl) carbodiimide. All films were characterized by attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The surface hydrophilicity of films was studied by water contact angle test and blood compatibility evaluated by Lactate dehydrogenase method (LDH Test). In vitro studie...
Covalent Binding of Heparin to Functionalized PET Materials for Improved Haemocompatibility
Materials, 2015
The hemocompatibility of vascular grafts made from poly(ethylene terephthalate) (PET) is insufficient due to the rapid adhesion and activation of blood platelets that occur upon incubation with whole blood. PET polymer was treated with NHx radicals created by passing ammonia through gaseous plasma formed by a microwave discharge, which allowed for functionalization with amino groups. X-ray photoelectron spectroscopy characterization using derivatization with 4-chlorobenzaldehyde indicated that approximately 4% of the-NH2 groups were associated with the PET surface after treatment with the gaseous radicals. The functionalized polymers were coated with an ultra-thin layer of heparin and incubated with fresh blood. The free-hemoglobin technique, which is based on the haemolysis of erythrocytes, indicated improved hemocompatibility, which was confirmed by imaging the samples using confocal optical microscopy. A significant decrease in number of adhered platelets was observed on such samples. Proliferation of both human umbilical vein endothelial cells and human microvascular endothelial cells was enhanced on treated polymers,
Journal of Biomedical Materials Research Part A, 2008
Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis; however, the immobilization of anticoagulant agents on the surface of the stent is a feasible method of improving stent compatibility. Heparin, a well-known anticoagulant, has been frequently used to coat the surfaces of certain biomaterials to attain blood compatibility. The compound 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide has often been utilized for the immobilization of heparin, but the critical carboxyl groups of heparin (with regards to heparin's anticoagulant activity) will be reduced by this method. This study examined possible methods of heparin immobilization without consuming these carboxyl groups. The 316L stainless steel surface was first activated with hexamethylene diisocyanate and then coupled with bis-amine-terminated poly (ethylene glycol) (BA-PEG) so as to create active amine groups. Sodium periodate (NaIO 4 ; SP) was then used to oxidize heparin to form aldehyde groups. The treated heparin could then be grafted onto the activated surface of the test material without losing its carboxyl groups. Effective surface modification of the hexamethylene diisocyanate-activated and BA-PEG-grafted 316L SS surface was confirmed using Fourier Transform Infrared Spectroscopy, electron spectroscopy for chemical analysis and a water contact angle test. After the heparin was immobilized on the BA-PEG-grafted 316L SS surface by SP, the surface showed an improvement in antithrombrin III (AT III) binding ability, its anticoagulant property, and hemocompatibility in comparison with heparin grafted by 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide.
Journal of Biomaterials Science, Polymer Edition, 1993
Appropriate surface modification has significantly improved the blood compatibility of polymeric biomaterials. This article reviews methods of surface modification with water-soluble polymers, such as polyethylene oxide (PEO), albumin, and heparin. PEO is a synthetic, neutral, watersoluble polymer, while albumin and heparin are a natural globular protein and an anionic polysaccharide, respectively. When grafted onto the surface, all three macromolecules share a common feature to reduce thrombogenicity of biomaterials. The reduced thrombogenicity is due to the unique hydrodynamic properties of the grafted macromolecules. In aqueous medium, surface-bound water-soluble polymers are expected to be highly flexible and extend into the bulk solution. Biomaterials grafted with either PEO, albumin, or heparin are able to resist plasma porotein adsorption and platelet adhesion predominantly by a steric repulsion mechanism.
Langmuir, 2012
Polyurethane (PU) was modified using isocyanate chemistry to graft polyethylene oxide (PEO) of various molecular weights (range 300−4600). An antithrombin−heparin (ATH) covalent complex was subsequently attached to the free PEO chain ends, which had been functionalized with N-hydroxysuccinimide (NHS) groups. Surfaces were characterized by water contact angle and X-ray photoelectron spectroscopy (XPS) to confirm the modifications. Adsorption of fibrinogen from buffer was found to decrease by ∼80% for the PEO-modified surfaces compared to the unmodified PU. The surfaces with ATH attached to the distal chain end of the grafted PEO were equally protein resistant, and when the data were normalized to the ATH surface density, PEO in the lower MW range showed greater protein resistance. Western blots of proteins eluted from the surfaces after plasma contact confirmed these trends. The uptake of ATH on the PEO-modified surfaces was greatest for the PEO of lower MW (300 and 600), and antithrombin binding from plasma (an indicator of heparin anticoagulant activity) was highest for these same surfaces. The PEO−ATH-and PEO-modified surfaces also showed low platelet adhesion from flowing whole blood. It is concluded that for the PEO−ATH surfaces, PEO in the low MW range, specifically MW 600, may be optimal for achieving an appropriate balance between resistance to nonspecific protein adsorption and the ability to take up ATH and bind antithrombin in subsequent blood contact.