Cholesterol Protects Phosphatidylcholine Liposomes from N,N-dimethyl-l-dodecanamine N-oxide Influence

摘要

The interaction of N,N-dimethyl-l-dodecanamine N-oxide (C12NO) 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 C12NO 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 C12NO 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 tor all n(CHOL):n(EYPC).