Figure 3.

Effective loading of siRNA with QD as determined by agarose gel electrophoresis. Lanes 2 to 5 correspond to a siRNA/PEG-QD ratios of 1:1, 1:10, 1:20, and 1:30. Lanes 1 and 6 correspond to QDs and a siRNA control, respectively. The green fluorescence intensities (siRNA) gradually increased from lanes 3 to lanes 6. In contrast, the red fluorescence intensities (PEG-QD) gradually attenuated from the lanes 1 to lanes 5, suggesting that a 1:1 ratio of PEG-QD and siRNA was the optimal proportion that provided a positive charge for cell binding and endosome escape. PEG, polyethylene glycol; QD, quantum dots; siRNA, small interfering RNA.