Polyurethane surface modification by graft polymerization of acrylamide for reduced protein adsorption and platelet adhesion (original) (raw)
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Platelet adhesion studies on dipyridamole coated polyurethane surfaces
European Cells and Materials, 2003
Surface modification of polyurethanes (PUs) by covalent attachment of dipyridamole (Persantin ®) is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP). This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM) was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exteriour surface.
Polyurethane surfaces modified by amphiphilic polymers: effects on protein adsorption
Biomaterials, 2000
Surface modi"cation of polyurethane (PUR) surfaces was carried out by using three di!erent amphiphilic polymers. Two of the polymers were graft copolymers, having backbones consisting of poly(methyl methacrylate-co-ethylhexyl acrylate) and poly(styreneco-acrylamide), respectively, and poly(ethylene oxide) PEO 2000 grafts. The third polymer was a commercially available poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer, Pluronic 9400. The polymers were designated ACRY, STY2, and PE94, respectively. Surface modi"cation was achieved by adsorption of the amphiphilic polymers at PUR surfaces from an aqueous solution, or by blending the amphiphiles into a PUR solution, followed by solution casting of "lms. The accumulation of the amphiphilic polymers at the PUR surfaces was observed by XPS and contact angle measurements. The ACRY and PE94 polymers were shown to adsorb poorly at the PUR surface, but gave strong surface e!ects when present in the PUR matrix. Protein adsorption was measured under static as well as under #ow conditions. The modi"ed surfaces had generally lower adsorption of blood proteins (HSA, Fg and IgG) than the unmodi"ed PUR surfaces. ACRY blend modi"ed surfaces had the lowest adsorption.
Journal of Biomedical Materials Research Part A, 2005
Ten specially synthesized polyurethanes (PUs) were used to investigate the effects of surface properties on platelet adhesion. Surface composition and hydrophilicity, fibrinogen (Fg) and von Willebrand's factor (vWf) adsorption, monoclonal anti-Fg binding, and platelet adhesion were measured. PUs preadsorbed with afibrinogenemic plasma or serum exhibited very low platelet adhesion, while adhesion after preadsorption with vWf deficient plasma was not reduced, showing that Fg is the key plasma protein mediating platelet adhesion under static conditions. Platelet adhesion to the ten PUs after plasma preadsorption varied greatly, but was only partially consistent with Fg adsorption. Thus, while very hydrophilic PU copolymers containing PEG that had ultralow Fg adsorption also had very low platelet adhesion, some of the more hydrophobic PUs had relatively high Fg adsorption but still exhibited lower platelet adhesion. To examine why some PUs with high Fg ad-sorption had lower platelet adhesion, three monoclonal antibodies (mAbs) that bind to sites in Fg thought to mediate platelet adhesion were used. The antibodies were: M1, specific to ␥-chain C-terminal; and R1 and R2, specific to RGD containing regions in the ␣-chain N-and C-terminal, respectively. Platelet adhesion was well correlated with M1 binding, but not with R1 or R2 binding. When these mAbs were incubated with plasma preadsorbed surfaces, they blocked adhesion to variable degrees. The ability of the R1 and R2 mAbs to partially block adhesion to adsorbed Fg suggests that RGD sites in the alpha chain may also be involved in mediating platelet adhesion and act synergistically with the C-terminal of the ␥-chain.
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.
Surface modification of polymers. V. Biomaterial applications
Journal of Polymer Science Part A: Polymer Chemistry, 1990
Polyethylene films were surface grafted with glycidyl methacrylate (GMA) by UV irradiating the film for 5 min together with benzophenone. Poly(ethy1ene glycol) (PEG) was attached to the grafted surface through reaction with the epoxy groups. This yielded a surface which consisted of 95% PEG as measured with ESCA. The adsorption of human transferrin onto this film was significantly reduced as compared with a pure polyethylene film. Heparin was also reacted with a GMA grafted PE surface. ESCA showed that heparin was grafted to the surface, and in vitro blood clotting tests on the heparinized PE surface showed a reduced thrombus formation. GMA grafted polystyrene wells were reacted with carbohydrazide, to the formed carbohydrazide surface a rabbit antibody raised against mouse urinary protein (RaMUP) was covalently coupled. The RaMUP coupled surfaces was used in the detection of mouse urinary protein (MUP) at low concentrations (ca. 1 ng/mL) with an ELISA technique. PEG grafted onto polymers form hydrogel surfaces which inhibit pro-Heparin grafted onto polymer surfaces prevent surface activated blood Antibodies attached to a polymer surface which can be used in the tein adsorption. clotting. detection of antigens.
Biomaterials, 2000
Polyethylene oxide (PEO) surfaces were prepared by the addition of PEO-containing amphiphilic block copolymers as surface modifying additives and of dicumyl peroxide (DCP) as a crosslinking agent in segmented polyurethane (PU). PEO-polypropylene oxide-PEO triblock copolymers (Pluronics) with di!erent PEO chain length (from 0 to 98) were used as the surface modifying additives. The PEO additives in the PU "lm were then crosslinked to be stably entrapped in the PU matrix. The crosslinking was done by free radicals produced from the decomposition of DCP in the "lm through heating (1203C) or ultraviolet irradiation (254 nm). The surface properties of the PEO additive-entrapped PU "lms were investigated by the measurement of water contact angles and electron spectroscopy for chemical analysis. The bulk properties such as water absorption, long-term "lm stability, and tensile strength and elongation at break, were also investigated. It was observed that addition of a small amount (5 wt% based on PU) of the PEO additives resulted in a considerable change of surface characteristics. The PEO additives were stably entrapped in the PU "lms by crosslinking of them, without signi"cant changes of bulk properties of the "lms. From the platelet adhesion test on the prepared PEO additive-containing "lm surfaces, it was observed that the platelet adhesion on the surfaces decreases with increase in PEO chain length of PEO additives. The "lm surface containing additive with long PEO chains (chain length of 98) was particularly e!ective in preventing platelet adhesion. The crosslinking of the PEO additives in PU "lms did not a!ect the behavior of platelet adhesion on the surfaces; the "lms with crosslinked PEO additives showed similar platelet adhesion on the surfaces to the "lms with uncrosslinked ones.
Determination of blood compatibility is an important problem in blood contacting devices. In this study, two classes of materials including polyurethane (based on polyethylene glycol and poly tetrametylene oxide) and polyvinyl alcohol samples, with different hydrophilicity properties were synthesized and their physico-chemical properties were compared. Water uptake ratio, FTIR spectroscopy, and contact angle measurement were conducted. In vitro biocompatibility experiments were undertaken using L-929 fibroblast cell lines which demonstrated desired cell viability for all samples after 7 days. The adhesion of platelets from human plasma was studied by optical microscopy. Blood coagulation time were also determined which revealed polyurethane based poly tetramethylene oxide has better interaction by blood elements among all samples.
Hemocompatibility of chitosan/poly(acrylic acid) grafted polyurethane tubing
2013
The activation and adhesion of platelets or whole blood exposed to chitosan (CH) grafted surfaces is used to evaluate the hemocompatibility of biomaterials. The biomaterial surfaces are polyurethane (PU) tubes grafted with an inner poly(acrylic acid) (PAA) and an outer CH or quaternary ammonium modified CH (CH-Q) brush.