Fig. 2.

Characterizations of GPS and GPSP nanoparticles. The hydrodynamic sizes of GPS (a) and GPSP (b), respectively. Insets are TEM images of GPS and GPSP nanoparticles, respectively. Scale bar, 100 nm. (c) The hydrodynamic sizes of GPS and GPSP measured at 0, 24, 48 and 72 h after preparation. (d) The hydrodynamic size of GPS and GPSP nanoparticles before and after incubation with 10% FBS for 2 h. (e) The zeta potentials of GPS and GPSP measured at different pH values. (f) Confocal images of 143B cells treated with Saporin_FITC, G5S_FITC, GPS_FITC and GPS_FITCP, respectively for 4 h. The endolysosomes were stained by Lysotracker red. Scale bar, 30 μm. (g) Mean fluorescence intensity of 143B cells treated with the above samples for 4 h. Viability of 143B (h) and MDA-MB-231 (i) cells treated with saporin, GPS and GPSP, respectively. GPSP pretreated with serum-free medium at pH 6.5 was also tested to confirm pH-responsiveness. **p < 0.01 analyzed by student's t-test, one tailed. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)