Figure 3: Percentage of EGFP gene silencing by (a) CS/siRNA, (b) PLA/siRNA, and (c) CS/PLA/siRNA polyplexes at various weight ratios in HeLa cells stably expressing EGFP after 4 days posttransfection at pH 7.4 (black bars) and pH 6.4 (gray bars). PEI (25 kDa)/siRNA polyplex at weight ratio of 2 : 1 was used as a positive control. Data are plotted as mean SD (). *Significantly different from the group(s) treated with the same weight ratio at pH 7.4. **Significantly different from the group(s) treated with the different weight ratio at same pH.