Platelet Repellent Properties of Hydrogel Coatings on Polyurethane-Coated Glass Surfaces

Abstract

Thromboembolism is a severe complication in patients with ventricular assist devices. Interactions of platelets with the artificial surface and pathological blood flow conditions could contribute to thrombus formation. Previous studies suggested that strongly swellable polymer coatings prepared from various poly(N-alkyl acrylamides) are bioinert as they repel proteins and cells. In this study, we tested structurally similar polymer coatings with varying degrees of crosslinking and swelling to explore if the bioinert character of such coatings is also valid under whole blood perfusion and shear stress. Glass substrates coated with medical grade polyurethane (PU) were modified with surface-attached poly(N-alkyl acrylamide) layers, which differed in crosslinking and in swelling. Slides were perfused with human blood containing fluoresceinated platelets at a shear rate of 1500 s for 3 minutes. Noncoated and PU-coated glass slides served as a reference for thrombogenic surfaces. We detected severe platelet adhesion on the reference surfaces. There was no platelet adhesion on poly(N-alkyl acrylamide) coatings with a swelling factor above 1.5-2 (p < 0.001 compared with PU). A lower swelling factor resulted in severe platelet adhesion. Different degrees of crosslinking ranging from 1% to 10% did not reverse platelet repellent properties of the representative polymer tested (p < 0.001 compared with PU).

Identification of acquired coagulation disorders and effects of target-controlled coagulation factor substitution on the incidence and severity of spontaneous intracranial bleeding during veno-venous ECMO therapy

“…Since extracorporeal circuitinduced platelet dysfunction is a major drawback in ECMO therapy, it has to be evaluated if the implementation of new materials or different designs of extracorporeal pumps and oxygenators have the potential to decrease platelet injury in the future. 25,26 Heparin…”

“…The design and coating of the extracorporeal components seem to play an important role with regard to activation of the coagulation system. 25,26,28 Patients in our study received a continuous infusion of heparin, with an aPTT target of 45 -55 seconds before implementation and a target of 40-45 seconds after implementation of the protocol. Consequently, the median aPTT measured was 50 sec in the control and 40 sec in the intervention group (p=0.002).…”

Prevention of Ocular Tenon Adhesion to Sclera by a PDMAA Polymer to Improve Results after Glaucoma Surgery

“…Neutral, surface‐attached hydrogels have been shown to be protein and cell repellent . The key concept behind such an approach is that proteins expressed by the cells show no enthalpic interactions (i.e., no Coulombic or hydrophobic interactions) with the coating.…”

Reducing Unspecific Protein Adsorption in Microfluidic Papers Using Fiber-Attached Polymer Hydrogels

“…Prominent examples are, e.g., polymeric hydrogels. With respect to such shielding layers on model surfaces (mostly planar, solid surfaces), many successful examples use surface-attached hydrogels that significantly reduce the binding of proteins to surfaces due to an entropic shielding effect [ 28 , 29 , 30 ]. The key idea here is that polymer and proteins have no enthalpic interactions and a penetration of the protein would cause an additional stretching of the surface-attached polymer layer and, thus, a large loss of entropy.…”