Adsorption Behavior of Lysozyme and Tween 80 at Hydrophilic and Hydrophobic Silica—Water Interfaces

摘要

Nonionic surfactants such as Tween 80 are used commercially to minimizeprotein loss through adsorption and aggregation and preserve native structure and activity.However, the specific mechanisms underlying Tween action in this context are not wellunderstood. Here, we describe the interaction of the well-characterized, globular proteinlysozyme with Tween 80 at solid–water interfaces. Hydrophilic and silanized, hydrophobicsilica surfaces were used as substrates for protein and surfactant adsorption, which wasmonitored in situ, with ellipsometry. The method of lysozyme and Tween introduction tothe surfaces was varied in order to identify the separate roles of protein, surfactant, and theprotein–surfactant complex in the observed interfacial behavior. At the hydrophobicsurface, the presence of Tween in the protein solution resulted in a reduction in amount ofprotein adsorbed, while lysozyme adsorption at the hydrophilic surface was entirelyunaffected by the presence of Tween. In addition, while a Tween pre-coat preventedlysozyme adsorption on the hydrophobic surface, such a pre-coat was completelyineffective in reducing adsorption on the hydrophilic surface. These observations wereattributed to surface-dependent differences in Tween binding strength and emphasize theimportance of the direct interaction between surfactant and solid surface relative to surfactant–protein association in solution in the modulation of protein adsorption by Tween 80.