It can't enter cells because it's too big and it's too water soluble so it can't go through cell membranes.

它的分子太大了所以无法进入细胞,而且还是水溶性的,所以它也无法穿过细胞膜

耶鲁公开课 - 生物医学工程探索课程节选

It's very water soluble and it's a big molecule, a very big molecule; it can't naturally get inside cells on its own.

它是一个水溶性极强的大分子,非常非常大的分子,质粒在自然状态下并不能自己进入细胞

耶鲁公开课 - 生物医学工程探索课程节选

Now this behaves very differently in water because part of it is water soluble, this part is, it's a molecule that would like to dissolve in water and part of it is like oil, it doesn't want to dissolve in water.

它们在水中表现出十分不同性质,因为一部分是水溶性的,这一部分是,是一种可以溶于水的分子,而另一部分就像油,不会溶于水中

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