A novel technique for studying the adsorption of plasma proteins on hydrophobic surfaces.

A method is shown for deducing the surface area of a pendant drop from the same profile photograph as is normally used to determine interfacial tension. Manipulation of such drops by a micrometer syringe then enables the pendant drop to be used as a surface balance for studying adsorption from bulk solutions. Results are given for the compression of films from solutions of albumin, gamma-globulin, fibrinogen, albumin-gamma-globulin mixture and albumin-gamma-globulin-fibrinogen mixture, and from serum, plasma, and blood at the isooctane-buffer interface. It is suggested that gamma-globulin and fibrinogen films are unfolded at the interface but that albumin films are different in that they consist of an inner, unfolded layer and an outer, globular layer. A film from serum resembles that from gamma-globulin alone, and not that from albumin-gamma-globulin mixture, whereas a film from plasma resembles that of fibrinogen at low compression and that of albumin-gamma-globulin-fibrinogen mixture at high compression. A film from blood is shown to resemble that from plasma.