Complexation of DNA and transfection reagent

Complexation is the process where plasmid DNA and transfection reagent interact to form the transfection complexes. Once both DNA and transfection reagent are diluted in serum-free medium, diluted transfection reagent should be added to diluted DNA solution to form the complexes. Since DNA is negatively charged and transfection reagent is positively charged, they will interact electrostatically. Take a look at the example below using Lipofectamine 3000 to see how they are formed.

In the case of Lipofectamine 3000, the optimal complex time of DNA with lipofectamine reagent is 5 minutes, and the mix is stable for up to 25 minutes.