Rheokinetic analysis of bovine serum albumin and Tween 20 mixed films on aqueous solutions

摘要

The surface dynamic properties (surface tension and surface dilational properties) of films formed by bovine serum albumin (BSA) and the surfactant Tween 20 were studied using Periodic sinusoidal interfacial compression and expansion in a superficial rheometer (ring trough). All measurements were performed at a constant temperature (20 degrees C) and at constant BSA concentration in the bulk phase (0.1% w/w). The surface dynamic properties were dependent on the protein/surfactant ratio in the bulk phase, on the interfacial composition (BSA, Tween 20, and BSA-Tween 20 mixture), and on the aqueous phase composition (i.e., presence of ethanol and sucrose). The results show that at higher protein concentrations in mixed films the surface dilational modulus is higher, which agrees with greater protein-protein interactions. However, lower superficial dilational modulus was observed at higher surfactant concentrations, which agrees with weaker surfactant-surfactant interactions. The dynamic surface tension and surface dilational modulus depend on subphase composition. The surface dynamic properties were tested by a kinetic model to monitor the unfolding and rearrangements of adsorbed BSA molecules including the existence of BSA-Tween 20 interactions. [References: 51]