Albumin Adsorption and Retention on C18‐Alkyl‐Derivatized Polyurethane Vascular Grafts

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Abstract
The short‐term albumin affinity and thrombo‐resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire‐reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short‐term (4‐h) exposure at femoral arterial sites in the dog. 125I‐Albumin was preadsorbed on tubes and then exposed to blood for successive 2‐h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity‐enhancing property of C18 alkylation in the short term. Blood‐preconditioning experiments suggested endogenous albumin has a high affinity for the C18‐alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18‐alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces.