The adjuvant activity of nonionic block polymer surfactants. III. Characterization of selected biologically active surfaces.

We evaluated the molecular and physicochemical properties of surfaces formed by defined layers of block copolymers which were especially effective as adjuvants or in the induction of granulomas. The copolymers which were adjuvants formed hydrophilic surfaces with a large area. They bound protein in a way which left it particularly accessible to antibody and induced the activation of complement. Copolymers which induced granulomas, in contrast, formed hydrophobic crystalline surfaces. They bound less protein and did not activate complement, but were toxic for macrophages. Their surfaces were found to be similar to those of the mycobacterial glycolipid trehalose-6,6'-dimycolate or quartz, in that they consisted of regular geometric arrays of hydrophilic and hydrophobic adsorptive domains. These studies demonstrated that changes in the size and arrangement of hydrophilic and hydrophobic blocks in copolymers produce a diversity of surface physicochemical properties which correlate with biologic activity.