2.3 Size and zeta potential of NCs
The size and zeta potential of the NCs were measured by a zetasizer. NCs with 200 pmol of siRNA were formed at N/P ratio 1, 3, and 5 of RS peptide and N/P ratio 5, 20, and 30 of RT peptide at room temperature for 30 minutes. Three N/P ratios of each peptide were selected to observe different aspects of NCs. Formed NCs were diluted to 200 nM in 1 ml DPBS and filtered with a 0.45-µm syringe filter (GVS, Bologna, Italy). Each NC was loaded in a cell (Ratiolab, Dreieich, Germany). Hydrodynamic radius and zeta potential were measured using a zetasizer (Malvern Panalytical, Ltd., Malvern, UK, n=3).