2.5. Determination of the Serum Stability of siRNA Polyplex

The polyplex with an N/P ratio of 10 was used for serum stability study, and experiment was carried out as described in the literature [35,39]. The naked siRNA and siRNA polyplex with a N/P ratio of 10 were incubated with 10% or 50% serum at 37 °C for different time (0.5, 1, 2, 4, 8, 12, 24, 48 and 72 h), and immediately mixed with gel loading buffer with or without 1% SDS. All samples were analyzed by 1% agarose gel electrophoresis containing GelRed in TBE buffer, and the siRNA band was visualized.