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).