Abstract
In this present work, the disk like micelles, called bicelle, composed by long-chain lipids (DPPC) and short-chain lipids (diC7PC) at the planar and the rim region, respectively, were used to form the complex with DNA in contrast to conventional vesicle based lipids-DNA complex. The fundamental research on the binary mixture of DPPC/diC7PC was first constructed, including the structure transformation in different mixture ratio and the phase transition upon the increasing temperature in the selected mixing ratio of DPPC/diC7PC=3/1. We then pack the DNA with the charged bicelles by doping cationic DC-chol or anionic DPPG. In the case of using cationic bicelles, self-assembly CB-DNA complexes were found to have the lamellar structure of alternating DNA-membrane. By turning the membrane charge density, the CB-DNA complex exhibited the benefits on its small size and tunable size with a constant DNA packing density. Moreover, it also showed the structure stability against the increased temperature. Subsequently, the DPPG doped bicelles were found to form the complexes with the DNA, called AB-DNA complex, only in the presence of sufficient calcium ions. Such the AB-DNA complex had the alternating membrane-ion-DNA lamellar structure which is similar with the CB-DNA complex. When calcium ions exceed a critical concentration, the DPPG MLV was found to coexistence with the AB-DNA complex since all the DNA was condensed in the AB-DNA complexes. The systematically demonstrated CB-DNA and AB-DNA complexes would provide a new stratagem to design new complexes which have distinct structure from previous vesicle-based lipids-DNA complexes.