Inhibitory effects of tyloxapol on the surface activity of albumin at the air/liquid interface

This study investigated the inhibitory effects of tyloxapol on the albumin surface activity at the air/liquid interface. Dynamic surface tensions under constant-area and pulsating-area conditions for mixed albumin/tyloxapol solutions were measured by using a drop volume tensiometer and a pulsating bubble surfactometer. The dynamic surface tension behavior under constant-area conditions demonstrated that by adding 1 ppm tyloxapol to a 5 ppm albumin solution, the long-time adsorption behavior or equilibrium surface tension behavior was strongly affected, but the surface activity of albumin was not inhibited significantly. However, at higher tyloxapol concentrations, such as 100 ppm, the inhibitory effect of tyloxapol on the albumin surface activity was clearly observed, even the albumin concentration was as high as 50 ppm. As for the dynamic surface tension behavior of 5 or 50 ppm albumin solutions under pulsating-area conditions, the dynamic surface tensions were not affected if only 1 ppm tyloxapol was present in the subphase. However, the tyloxapol-dominated dynamic surface tension behavior was observed if 100 ppm tyloxapol was added. The results suggest that the albumin surface activity or adsorption could be inhibited if appropriate amounts of tyloxapol are present, which might be applied to prevent the deleterious effect of albumin on the surface tension-lowering ability of lung surfactants.