Surface tensiometric study of multiple complexation and hemolysis by mixed surfactants and cyclodextrins

The suppression of hemolysis induced with 1.0 mM dodecyltrimethylammonium bromide (DTAB) or 1.6 mM 3-(dimethyldodecylammonio)-1-propanesulfonate (DDAPS) by alpha-, beta-, and gamma-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 gamma-CyD are larger than their 1:1 binding constants. This cooperative binding of DTAB and DDAPS to gamma-CyD is ascribed to the fact that the gamma-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 alpha-CyD approximate to beta-CyD > gamma-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 CBD. All the CyDs can bind the surfactants more strongly than phospholipid and cholesterol in the erythrocyte membrane.