Effect of zwitterionic betaine surfactant on interfacial behavior of bovine serum albumin (BSA)

Abstract The interfacial adsorption and denaturation of proteins is a significant concern for the loss of protein structure and function during protein processing or storage. Surfactants can be used to prevent interfacial damage to proteins. Zwitterionic surfactants have shown intriguing effects on stability and activity of proteins. The aim of this research was to study the effect of cocamidopropyl betaine (CAPB), a non-denaturing zwitterionic carboxy betaine containing surfactant, on the air/water interfacial adsorption of a model protein bovine serum albumin (BSA). Dynamic and equilibrium surface tensions were measured using the pendant drop method. The results of surface tension measurements were coupled with a thermodynamic analysis, based on the interface and bulk chemical potentials, to estimate the surface coverage of the components and to calculate surface adsorption. Our results indicated that CAPB can effectively associate with the protein at different concentrations, even at concentrations lower than the critical micelle concentration (CMC). Furthermore, the addition of the protein significantly increased the CMC of the CAPB form 45 ppm to 407 ppm. Most importantly, CAPB prevented the adsorption of the protein at the interface. The interface of aqueous solution of CAPB+BSA was also compared with the Triton X-100 + BSA. Results of this study will help us to understand surfactant+protein interactions at interfaces.