The lipids will form a bi-layer where the water soluble part of the lipid points out of this layer and the oily part points in.

脂质会形成双层膜,水溶性部分朝向膜层外,而脂溶性的部分朝向双层膜内部

耶鲁公开课 - 生物医学工程探索课程节选

So you form DNA lipid complexes and because the DNA is complexed with lipids it's more soluble in membranes and more likely to enter cells.

形成DNA脂类复合体之后,因DNA同脂类复合,其脂溶性大大增加,更容易进入细胞

耶鲁公开课 - 生物医学工程探索课程节选