| dc.description.abstract | To improve the transfection efficiency of C-terminal stearyl Indolicidin (ILs), a helper lipid, dioleoylphosphatidylethanolamine (DOPE), has been applied to mix with ILs at a molar ratio of 1:3 (ILs0.3L). Previous study indicates that ILs0.3L exhibits higher transfection efficiency than that of ILs. Therefore, a series of analyses were perfomed in this study to understand the promotion mechanism of helper lipids. The circular dichroism (CD) spectra showed that the structure of IL was completely random coiled, whereas ILs and ILs0.3L both exhibited partial α-helix properties. These results indicated that stearyl modiciation allow IL to self-assemble, which also led secondary structure formation. We used small angle X-ray scattering (SAXS), dynamic light scattering (DLS), and transmission electron microscope (TEM) to analyze self-assembled structures and their sizes. In a neutral environment, ILs and ILs0.3L formed cylindrical micelles and unilamellar vesicles, respectively. The overall structure of ILs0.3L was smaller than ILs. ILs0.3L/DNA was also smaller than ILs/DNA, suggesting that ILs0.3L/DNA may enter cells easier. The flow cytometry experiments showed that DNA delivered by ILs0.3L and ILs both through endocytosis. Interestingly, only ILs0.3L/DNA could enter cells through macropinocytosis. In an acidic environment, TEM results showed that the structure of ILs/DNA became compact, whereas ILs0.3L/DNA demonstrated structural reorganization and loose structures. Due to the unstability of ILs0.3L/DNA, the heparin competition experiment showed that acidic environment promoted DNA separated from ILs0.3L, which is essential for the protein expression of ingested genes. Confocal microscopy also showed that DNA delivered by ILs0.3L and ILs could both escape from endosome. Based on the abovementioned results, ILs0.3L owns smaller particle size, additional access to cells, and the capabilities of endosomal escape as well as intracellular DNA release, so its transfection efficiency is better than that of ILs. | en_US |