**3.4 Lipoplex formation**

Enhanced green fluorescent plasmid pEGFP (either labeled for uptake studies or unlabeled for transfection studies) was mixed with DC-30® in a lipid/DNA ratio (w/w) of 5:1 according to the following protocol: lyophilized DC-30® was redispersed in sterile transfection medium (TM; 250 mM saCcharose, 25 mM NaCl) at a concentration of 1 mg/ml and incubated for 30 min at room temperature. Plasmid DNA and the respective amount of DC-30®-dispersion were diluted separately into equal volumes of TM in order to achieve the desired lipoplex concentration in 200 µL of lipoplex preparation. The dilutions were combined discontinuously by pipetting the plasmid into the liposome solution, gently mixing and incubating for at least 30 min at room temperature to allow the formation of the lipoplexes.
