Nanoparticles stability Assays

miR-9 (20 μM) was mixed with PL-1 at a molar ratio of 20:1 (PL-1: miR-9) and incubated at room temperature for 10 min. For RNase A degradation stability, 1 μL of RNase A (diluted to 1 ng/μL, Takara, Japan) was added and incubated at 37 ºC with time course. For serum stability assay, mouse serum was added at a final concentration 50% (v/v), the samples were incubated at 37 ºC with time course. 3 μL samples were frozen with liquid nitrogen and stocked at -80 ºC. Before loading to agarose gel electrophoresis, the samples were treated with heparin (10 μg) to release intact miR-9. Naked miR-9 was used as a control.