2.4. Size and zeta potential measurement
Size and zeta potential of complexes were measured by dynamic light scattering (DLS). Based on the results of the previous gel retardation assay, a 20:1 N/P ratio was determined for the rest of the experiments due to the stable complex formation of all fusion peptides. 200 pmol siRNA and each peptide were self-assembled at a 20:1 N/P ratio, as described above. After 30 minutes, the complexes were diluted with HBSS to a final siRNA concentration of 200 nM. Then, the 200 nM solution was filtered with a 0.45 μm syringe filter (GVS, Bologna, Italy). After vortexing for 30 seconds, 1 mL of the complexes was loaded into a cuvette (Ratiolab, Dreieich, Germany) to measure the size and disposable folded capillary cell (Malvern Panalytical Ltd., Malvern, UK) to measure the zeta potential. The size and zeta potential of complexes were measured using a Zetasizer Nano ZS (Malvern Instruments Ltd., Worcestershire, UK).