Effect of protein adsorption on the blood-contacting response of sulphonated polyurethanes (original) (raw)
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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.
Anticoagulant effects of sulphonated polyurethanes
Biomaterials, 1992
polyurethanes have been shown to have excellent blood contacting properties. In this paper, similar polyurethanes which are water soluble have been investigated to determine their influence on thrombus formation. These polymers were shown to delay clotting times in the following ways: by direct complex formation between the polymer and thrombin; by interference with fibrin polymerization;
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.
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.
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...
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.
Journal of Materials Science: Materials in Medicine, 2004
Biomaterial-induced thrombosis remains one of the main complications of vascular implant devices. Preadsorbed proteins on the biomaterial/blood interface will modify the adhesion and activation of platelets (PTLs) during the initial contact-phase. Our results clearly show that PTL-adherence on biomaterials is in¯uenced not only by protein preadsorption, but also by¯ow conditions. The covalent coating of TCPS and glass by phosphorylcholine (PC) induces a signi®cant decrease of PTL adhesion but leads to a slight, but nevertheless signi®cant activation of PTL, which was detected by the induction of P-selectin expression using FACS analysis. Methodologically, the visualization of PTL adhesion gave more reliable results for measurement of PTL adhesion than the cell-enzyme immunoassay (EIA) for P-selectin. Human citrated plasma caused an inhibition of PTL. It is probable, that the contained sodium citrate may inhibit PTL adhesion by its calcium ion-binding capacity. The¯ow experiment as dynamic system is in our view absolutely essential for the evaluation of biomaterials for vascular prosthesis, and is in accordance with the international standards. The results of the experiments also suggest that investigations under static and¯ow conditions are needed to determine the in¯uence of protein adsorption on mixed blood cell populations, for example, on PTL and PMN mixtures/co-cultures in order to achieve a better simulation of the in vivo situation.
Biomaterials, 1993
Surface modification of polyurethane by glow-discharge treatment and subsequent graft polymerization of acrylamide was studied. The modified hydrophilic surfaces were characterized by the measurements of dynamic contact angle and zeta potentials and examined for protein adsorption behaviour and platelet adhesion. Data from in vitro and ex vivo experiments indicated a reduction of protein adsorption and platelet adhesion for the hydrophillic graft polymers, the extent of which was correlated to polymer graft density.