We have few researchers in our lab trying to transfect siRNA-GFP into K562 cells using common lipid-based methods (e.g Lipofectamine, Fugene, Turbofect) but the efficiency was very low. The efficiency goes up only when we switch the electroporation-based method (e.g. Nucleofection, Neon). I think lipid-based transfection works well on adherent cells but not for floating (non-adherent) cells as most of the lipid complex would just sink to the bottom of the flask leaving most cells happily floating on top.
I will be grateful, if anyone share their knowledge about a good method for fixing and permeabilizing cells for inserting dyes inside the nucleus and then use the flow cytometry to measuring.