Cholesterol protects phosphatidylcholine liposomes from N,N-dimethyl-1-dodecanamine N-oxide influence

Abstract

The interaction of N,N-dimethyl-1-dodecanamine N-oxide (C 12 NO) with egg yolk phosphatidylcholine (EYPC) liposomes containing cholesterol (CHOL) was studied. The perturbation of CHOL-EYPC bilayers in unilamellar liposomes (ULL) was observed by the leakage of fluorescence probe calcein. Weak leakage is observed at low surfactant concentration c C12NO (minimal perturbation of the bilayer) followed by an intensive leakage at a middle c C12NO (creation of pores). No change in fluorescence intensity was measured at high c C12NO (calcein totally released from liposomes). The higher CHOL amount in the bilayer, the more surfactant is needed to create pores in the bilayer. Solubilization of CHOL-EYPC ULL induced by C 12 NO was studied turbidimetrically. The solubilization curve consists of three parts: saturation of bilayer at low c C12NO (liposomes are preserved), followed by solubilization (liposome - mixed micelle transition) and post-solubilization. The C 12 NO concentration needed for the onset of the solubilization raise with the increase of n CHOL :n EYPC. The structure of liposomes is still preserved at total calcein release for all n CHOL :n EYPC.