INTERACTION OF PLASMA-PROTEINS WITH ARTIFICIAL SURFACES - PROTEIN ADSORPTION-ISOTHERMS

Abstract

A simple technique using a small disc which is dipped into a 125I-labeled protein solution was devised to study the adsorption of human albumin, fibrinogen and Ig[immunoglobulin]G onto Cuprophane or PVC [polyvinylchloride). The purity of these human plasma proteins was examined carefully with polyacrylamide gel electrophoresis and immunochemical methods. The adsorption isotherms of albumin, fibrinogen and IgG show a Langmuir type adsorption. Delipidation of albumin did not alter the albumin affinity to Cuprophane and PVC. The surface saturation concentration (ng/cm2) for albumin, fibrinogen, or IgG were all more on PVC (a hydrophobic surface) than on Cuprophane (a hydrophilic surface). The competitive adsorption of 1 protein species in 2- or 3-protein mixture was also studied. Albumin and fibrinogen compete with each other for adsorption. The effects of IgG on the adsorption of albumin or fibrinogen were inconsistent and not predictable; the reason for this is unknown. The effect of laminar flow on albumin adsorption was studied with a specially designed Richardson flow chamber. In general, flow caused an increase in albumin adsorption over that at static conditions. The increase of albumin adsorption was more pronounced also for PVC than for Cuprophane from 1-10 ml/min.