Anwendungsmöglichkeiten für Ionenpaar-Amphiphile / Potential application of ion-pair amphiphiles

Abstract

The paper deals with studies on stoichiometric mixtures of a series of sodium alkylsulphonates (AS-n) with N-dodecyl-N-methylmorpholinium chloride (DMM). The aim of the work was to check the ability of anionic-cationic pair formation in mixtures of these salts and to find out if such a pair, once formed, has improved potential biological activity in comparison with DMM salt, that belongs to the biologically important morpholinium salts [1]. The enhanced biological activity was predicted on the base of the results of other experiments [2, 3]. To prove this prediction two different lipid models were used: liposomes and planar lipid membranes (black lipid membranes - BLM). The praseodymium ion release from liposomes (NMR technique) and the stability of BLM in the presence of DMM or sulphonates alone and in the presence of their equimolar (1:1) mixtures were investigated. It was found that the mixtures of DMM and AS-n with alkyl chains not shorter than C 10 H 21 in the case of black lipid membrane experiments or C 8 H 17 in liposome experiments exhibited increased efficiency in changing the stability of BLM and releasing Pr 3+ ions from liposomes in comparison with the efficiency of DMM or particular AS-n when they acted individually on model membranes. The results obtained seem to point out that sodium sulphonates with sufficiently long alkyl chains most probably form the postulated ion-pairs with DMM molecules. Such a pair can interact more easily with the membrane lipid molecules due to the diminished polarity of its head group and also due to a cylindrical shape that such molecule achieves. The overall effect is reflected in the observed change of the interaction with the lipid membrane.