Adsorption properties and biological activity of catanionic mixtures containing derivatives of quaternary lysosomotropic substances

The main aim of the study presented was to determine and characterize the adsorption properties of catanionic mixtures with quaternary derivatives of lysosomotropic substances (QDLS). The surfactants investigated were quaternary ammonium salts belonging to the group of esterquats: fatty acids N,N-dimethylaminoethylesters methobromides (DMM-n), fatty acids N,N-dimethyl-aminopropylesters methobromides (DMPM-n), and derivatives of amine esters with double alkyl chains (M2M-n). Three mixed systems were considered: DMPM-9 + DBSNa, DMM-9 + DBSNa and M2M-9 DBSNa with components at different molar ratios. Quantitative and qualitative description of the adsorption process (Frumkin's equation) was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. Moreover, the size of micelles was measured by dynamic light scattering method. Contact angle of QDLS was investigated on paraffin, quartz and glass surfaces. The results obtained indicated that most of the systems studied revealed synergistic effect in adsorption and wetting properties. It was found that the structure of monolayers formed in mixed systems was strongly affected by the composition of the bulk solution. Especially strong reduction in surface tension and cmc value was observed for equimolar mixtures. In order to evaluate the effects of surface activity of catanionic mixtures on their biological potential, in vitro studies on human cancer cells were undertaken. The results of the study presented suggest a correlation between the surface properties and the anticancer potential of catanionic mixtures. The data obtained show that catanionic mixtures suppress the cancer cells' proliferation more effectively than their individual components. (C) 2013 Elsevier B.V. All rights reserved.