Postadsorptive transitions in fibrinogen: influence of polymer properties

Changes in the fibrinogen molecule after its adsorption to biomaterials may be important in determining blood compatibility. Previously, postadsorptive transitions were detected by measuring the elutability of adsorbed proteins with surfactant solutions. The elutability decreased with increased residence time, suggesting that protein-surface interactions increased with residence time. In this study, we have examined the effects of polymer structure and composition, chain mobility, and hydrophobicity on the postadsorptive transitions of fibrinogen. Glassy, rigid polymers showed high fibrinogen adsorption, regardless of whether the polymer was hydrophilic or hydrophobic. However, the binding strength (as measured by elutability) was much lower on hydrophilic polymers and oxygen-containing hydrophobic polymers. Short-term transitions, requiring 2 h or less after adsorption, were observed only on hydrophobic polymers that contained no oxygen. More gradual transitions were observed on hydrophobic polymers containing oxygen, but only after a lag time of 1-4 h.