Immobilized albumin-immunoglobulin G for improved hemocompatibility of biopolymers.

Efforts to render blood contacting surfaces less thrombogenic have included chemical modification of the polymer, as well as surface modifications with proteins, anticoagulants, or antiplatelet agents. Studies reported from this laboratory in the past have shown that certain surfaces pretreated with albumin-Immunoglobulin G (alb-IgG) become relatively more hemocompatible (reduced platelet adhesion, minimal thrombus). However, absorbed proteins, including alb-IgG, desorb rapidly when exposed to circulating blood. Therefore, efforts were made to immobilize alb-IgG on glass or Biomer as follows: a 2 mg/ml solution of IgG was crosslinked with glutaraldehyde on the test surface. Crosslinked IgG was then treated with mercaptoethanol to reduce the disulfide bonds, followed by incubation with albumin previously reduced with mercaptoethanol under conditions that allowed reassociation of disulfide bridges between albumin and crosslinked IgG. Alb-IgG immobilized at the test surface following this method was found to remain at the interface when the surface was exposed to blood in vitro for up to 7 days under static conditions. Glass or Biomer surfaces with crosslinked Alb-IgG showed considerable reduction in the adhesion of 111In-platelets and adsorption of 125I-fibrinogen when test surfaces were analyzed in a flow chamber. Under identical experimental conditions, surfaces with crosslinked albumin alone were not effective in reducing the adhesion of platelets. Crosslinked IgG or immobilization of IgG on crosslinked albumin following the above methods rendered the surfaces more thrombogenic. It was noted, however, that crosslinked proteins on Biomer were dislodged rapidly in areas with turbulent flow.(ABSTRACT TRUNCATED AT 250 WORDS)