Contact activation during incubation of five different polyurethanes or glass in plasma (original) (raw)
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Biomaterials, 2003
A medical grade segmented polyetherurethane (PEU) was treated with a low-powered gas plasma using O 2 , Ar, N 2 and NH 3 as the treatment gases. Changes in the surface functional group chemistry were studied using X-ray photoelectron spectroscopy. The wettability of the surfaces was examined using dynamic contact angle measurements and the surface morphology was evaluated using atomic force microscopy. The influence of the surface modification to the polyurethane on the blood response to the polyetherurethane was investigated by measuring changes in the activation of the contact phase activation of the intrinsic coagulation cascade. The data demonstrate that the plasma treatment process caused surface modifications to the PEU that in all cases increased the polar nature of the surfaces. O 2 and Ar plasmas resulted in the incorporation of oxygen-containing groups that remained present following storage in an aqueous environment. N 2 and NH 3 plasmas resulted in the incorporation of nitrogencontaining groups but these were replaced with oxygen-containing groups following storage in the aqueous environment. In all plasma treatments there was a lowering of contact phase activation compared to the untreated surface, the N 2 and NH 3 treatments dramatically so.
Effect of protein adsorption on the blood-contacting response of sulphonated polyurethanes
Biomaterials, 1993
Polyurethanes which are grafted with propyl sulphonate functionality have excellent bloodcontacting properties. In a canine ex vivo series shunt experiment, very low platelet deposition was observed on these materials and those platelets which were adherent remained unspread. In contrast to this, large amounts of fibrinogen, of the order of a monolayer or greater, were deposited on these surfaces in this ex vivo experiment. This led to the hypothesis that perhaps the deposited fibrinogen did not retain its platelet-adhesive activity. In this paper, we investigate the possibility that these materials exert their antithrombotic effects through the adsorbed protein layer. Protein adsorption kinetics and isotherms on these sulphonated polyurethanes are determined. Multilayer protein adsorption or absorption into the hydrogel-like materials is found for each of the proteins studied, and the greatest amounts of protein are seen on the most highly sulphonated polyurethanes. Further, the blood-contacting response of these materials is investigated after pre-conditioning with either fibrinogen, fibronectin or albumin. When these materials are pre-adsorbed with either fibrinogen or fibronectin, a very thrombogenic response was observed, which suggests that the platelet-adhesive activity of these proteins is not being reduced. Pre-adsorption of albumin did not improve the thromboresistance of these surfaces.
Hydrochloric acid treated polyurethanes for temporary blood contacting biomaterials applications
Biomedical Research-tokyo, 2017
This research paper investigated the surface characterization and blood compatibility of polyurethane surface modified with Hydrochloric Acid (HCl) treatment for 30 min and 60 min respectively. The surface modified polyurethane with HCl shows increase contact angle and resulted in well-defined structure with unique orientation evident by SEM study. To evaluate the effect of acid treatment on the coagulation cascade, Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) were measured. The HCl treated PU showed increasing Prothrombin Time (PT) and Activated Partial Thrombin Time (APTT) implying improved blood compatibility of the surfaces. The results of Hemolysis assay of the treated surface showed less number of damaged RBC’s compared to control. Compared to control the number of platelet adhesion on the surface of surface modified PU was found less and thereby reduce the chances of activation of blood coagulation cascade suitable for blood contacting biomaterial ap...
In vitro Interactions of Biomedical Polyurethanes with
2016
ABSTRACT: Three commercial medical-grade polyurethanes (PUs), a poly-ether-urethane (Pellethane), and two poly-carbonate-urethanes, the one aromatic (Bionate) and the other aliphatic (Chronoflex), were tested for macrophages and bacterial cells adhesion, in the presence or absence of adhesive plasma proteins. All the experiments were carried out on PUs films obtained by solvent casting. The wettability of these films was analysed by measuring static contact angles against water. The ability of the selected PUs to adsorb human fibronectin (Fn) and fibrinogen (Fbg) was checked by ELISA with biotin-labelled proteins. All PUs were able to adsorb Fn and Fbg (Fn>Fbg). Fn adsorption was in the order: Pellethane>Chronoflex>Bionate, the highest Fbg adsorption being detected onto Bionate (Bionate>Chronoflex>Pellethane). The human macrophagic line J111, and the two main bacterial strains responsible for infection in humans (Staphylococcus aureus Newman and Staphylococcus epiderm...
Influence of test protocol in determining the blood response to model polymers
2002
A multi-parametric, multi-center evaluation of three polymers was performed measuring their response to blood contact. The purpose of this study was to pinpoint differences in tests performed for assessing``basic'' hemocompatibility on identical materials at different centers and attempt to rationalize. Assays for platelet adhesion, activation, aggregability and activation of the coagulation system in addition to an ex vivo patency assay were performed at four centers across Europe, using protocols favored by each center for determining the blood-contacting performance of a biomaterial. Three polymers were chosen for their expected blood response spanning the range of undesirable to desirable: ethylenevinylacetate (EVA), polyvinylchloride (PVC) and PVC modi®ed with polyethylene oxide (PEO). The assays were ranked in terms of their ef®cacy compared to cost and simplicity. A correlation between assays was calculated, indicating the ability of one test to correctly determine the blood response compared to another. Some assays were unable to distinguish between materials, but of the assays which could, the materials were ranked in the following order: EVA; PVC; PVC-PEO, EVA producing the most undesirable response. It is concluded that many commonly used assays for determining hemocompatibility are inappropriate, but there are simple and reliable test methods available which correlate well with the more sophisticated protocols.
In vitro blood reactivity to hydroxylated and non-hydroxylated polymer surfaces
Biomaterials, 2007
Complement activation on hydroxyl-group-bearing surfaces is regarded as the main reason for granulocyte activation in applications of blood-contacting medical devices such as extracorporeal blood purification. However, the factors inducing the cell adhesion so far remained ambiguous. For a dedicated research, whole blood was incubated with a set of structurally similar polymer coatings on glass with either hydroxy or ether functionalities. By co-incubation of an activating with a non-activating surface, the reaction of granulocytes activated by complement fragments on non-activating surfaces could be evaluated. As expected, hydroxyl-terminated polymer layers induced much higher levels of complement activation than those with ether functionalities. Leukocyte activation, as measured by the expression of CD11b, correlated closely with the presence of free complement fragment C5a. However, adhesion of leukocytes was rather associated with the adsorption of activated fragments of C3 than with the activation level of the cells. Moreover, it was found that adsorbed quantities of fibrin and fibrinogen had little influence on leukocyte adhesion. It is concluded that the activation of leukocytes is triggered by soluble complement factors such as C5a while their adhesion on hydroxy-bearing surfaces is mainly triggered by the presence of surface-bound complement fragment C3b. r
Journal of the American Chemical Society, 1995
Conjugate molecule 2, in which theophylline and a 4-azidobenzoyl group are separated by a short spacer chain, was adsorbed onto polyurethane sheets and subsequently irradiated with ultraviolet light. The resulting photoreaction at the polymer surface led to immobilization of theophylline. The modified polymer surface thus obtained was subjected to different physico-chemical experiments, Le., X-ray photoelectron spectroscopy, attenuated total reflection infrared spectroscopy, and water contact-angle measurements. These experiments clearly pointed out that theophylline is linked to and exposed at the surface of the modified polymer. In addition, the modified surface was subjected to various in vitro biochemical tests, Le. (i) a thrombogenicity assay in which the surface was contacted with either platelet-rich blood plasma (PRP) or platelet-free blood plasma (PFP), and formation of thrombin was monitored as a function of time and (ii) studies focussed on adhesion of blood platelets to the surface, both in a static system, and under flow conditions. The latter experiments were conducted with a parallel-plate flow chamber. The biochemical tests revealed that the modification leads to a marked increase of the lag-time for surface-induced thrombin formation provided that PRP was used in the test (experimental lag-times for the modified surface and the untreated control: ca. 1270 and 576 s, respectively). Using PFP, the lag-times of the modified and untreated surfaces do not differ substantially (698 and 549 s, respectively). Studying adhesion of blood platelets in a static set-up, the modified surface showed adhesion of only few platelets with nearly unchanged morphology, whereas extensive adsorption of activated platelets (evident from spreading and formation of pseudopods) was found for the untreated control surface. These observations were made with scanning electron microscopy. The experiments with the parallelplate flow chamber showed adhesion of approximately 30.000 platelets per square cm of the modified surface, for shear rates in the range 12.5-300 s-I. The density of adhered platelets for the untreated surface was found to be higher by one order of magnitude.