Interaction between Tween-20 and BSA

The interaction between Tween-20 and BSA was studied by surface tension and isothermal titration microcalorimetry. The results show that there is a weak interaction between Tween-20 and BSA and the Tween-20 molecules can replace BSA molecules adsorbed on the surface. A competition adsorption between Tween-20 and BSA occured at the surface of mixed solution. The tendency of change of the properties of the BSA/Tween-20 mixed system with temperature is similar to that of the single non-ionic surfactant. In the range of BSA concentration from 3.7x10(-5) kg center dot L-1 to 1.1x10(-5) kg center dot L-1, the cmc of Tween-20 does not change with BSA concentrations. When the amount of Tween-20 is fixed, the thermal effects of the interaction between BSA and Tween-20 does not depend on the BSA concentration. The thermodynamic parameters of the mixed solutions in the presence or absence of BSA indicate that the cmc of Tween-20 decreases and the value of entropy change of the system increases in the presence of BSA in solution.