Fig. 3

The lysosomal escape of NPs in a MCF7 cells and b MCF7/MDR breast cancer cells. In MCF7 and MCF7/MDR cells, the yellow fluorescence was very strong in the unbound VRP-FITC groups, suggesting that unbound VRP-FITC remained in the lysosomes. However, the yellow fluorescence became weaker or even disappeared in the RGD-NPs group, suggesting that the RGD-NPs had successfully escaped from the lysosomes. The NPs gave green fluorescence, lysosomes gave red fluorescence, and the nucleus gave blue fluorescence. The presence of the yellow color was due to the overlap of green and red fluorescence, suggesting that the NPs had entered the lysosomes