Changes in protein adsorption on polycarbonate due to L-ascorbic acid.

When a synthetic material is introduced into blood, plasma proteins are rapidly adsorbed on to its surface, followed by the attachment of formed elements of blood, leading to thrombus formation. Previous research reported that vitamin C (L-ascorbic acid) prolongs the clotting time due to the formation of vitamin C-calcium complexes, which reduce the availability of Ca2+ ions for the clotting mechanism in in vitro conditions. Contact angle and platelet adhesion studies have indicated that vitamin C modifies the surface-protein interaction and surface-platelet binding at the interface. In this paper an increased thickness of protein layer deposited on the polycarbonate substrate has been observed in the presence of vitamin C (approximately 50 A) using ellipsometric measurements. Further polyacrylamide gel electrophoresis (PAG) and infrared attenuated total reflection spectroscopy (IR-ATR) techniques have provided a better understanding of the interfacial phenomena. It seems, that the adsorption of albumin is increased, relatively, in the presence of vitamin C, when compared with that of fibrinogen and gamma-globulin from an equal amount of protein mixture.