4.6. Gel Retardation Assay

The best conditions for lipoplex (DDC642 liposomes + nucleic acid) formation, which is dependent on the chemical properties of the oligonucleotide (e.g., length, net charge and chemical modifications), were determined using a gel retardation assay. For that, a serial dilution (0.5 µg, 1 µg, 2 µg and 4 µg) of all three AONs was prepared in a final volume of 6-µl ddH₂O. Each dilution was combined with 4-µl DDC642 (4 µg/µL) under gentle vortexing for 15 s and incubation at room temperature for 10 min. GelRed^® Nucleic Acid Gel Stain (Biotium, Fremont, CA, USA) was used to visualize the oligonucleotides; the mixtures were electrophoretically analyzed on a 1% agarose gel and visualized under UV light.