Collagen at interfaces. I. In situ collagen adsorption at solution/air and solution/polymer interfaces.

Collagen was isolated from rat tail tendons and acetylated with 1-14C acetic anhydride. In situ adsorption of this collagen from a buffer solution (pH = 2.7) was measured at the interfaces to air, polyethylene and polyethylene grafted with poly(maleic acid), respectively. The kinetics of adsorption were recorded for all surfaces studied and the corresponding diffusion coefficients for collagen in solution with various protein concentrations were calculated. The desorption of collagen from polymer surfaces was also studied. These experiments reveal the existence of both a reversibly and an irreversibly adsorbed collagen layer on the polymers tested. The desorption/adsorption ratio for the polyethylene is higher than that for the grafted polyethylene indicating stronger interactions of collagen with the grafted surface than with the non-modified polyethylene.