Fig. 4

In vitro transcellular transportation and penetration ability of nanoparticles. A Qualitative analysis of the fluorescence intensity of NPs staying in cells by fluorescence microscopy; scale bars: 50 μm. B, C Quantitative analysis of the fluorescence intensity of NPs remaining in the cells by flow cytometry. D Schematic illustration of the transcellular transportation of NPs. E, F Qualitative analysis of the transmembrane ability of nanoparticles. G Representative confocal microscopy images of the penetration of PN, PRN and PGN into B16F10 tumor spheroids to different depths. Scale bar: 200 μm. Data are presented as the mean ± SD (n = 3). **P < 0.01.