Surface Tensiometric Study of Multiple Complexation and Hemolysis by Mixed Surfactants and Cyclodextrins

Abstract

The suppression of hemolysis induced with 1.0 mM dodecyltrimethylammonium bromide (DTAB) or 1.6 mM 3-(dimethyldodecylammonio)-1-propanesulfonate (DDAPS) by α-, β-, and γ-cyclodextrins (CyDs) is determined as a function of CyD concentration at 310 K, and is correlated with the surface tension values of their solutions. These surface tension data allow us to estimate the 1:1, 1:2, and 2:1 binding constants of DTAB or DDAPS with these CyDs. The 2:1 binding constants of DTAB and DDAPS with γ-CyD are larger than their 1:1 binding constants. This cooperative binding of DTAB and DDAPS to γ-CyD is ascribed to the fact that the γ-CyD cavity has an adequate space to accommodate two alkyl chains. Both the capabilities of CyDs for hemolysis suppression and surface tension elevation are in the order α-CyD ≈ β-CyD > γ-CyD for 1.0 mM DTAB and 1.6 mM DDAPS. The suppression of DTAB- or DDAPS-induced hemolysis for all the CyDs can be quantitatively predicted from the observed surface tension data, regardless of the kind and concentration of CyD. All the CyDs can bind the surfactants more strongly than phospholipid and cholesterol in the erythrocyte membrane.