Fig. 4

The barrier-penetrating property of intravesical nanomotors. (a) Schematic diagram of the Transwell diffusion assay. (b) Quantification of the transmucosal proportion of Au-Pt@ur-cy5 NPs after a timed diffusion at 37 °C; a porcine mucus layer with the thickness of 20 μm was seeded onto a Transwell polycarbonate membrane in a pore size of 0.4 μm, and 100 µL of NPs + solvent was afterward loaded onto the upper Transwell chamber with 1000 µL of PBS buffer (pH = 7.4) in the lower chamber; NPs in the lower chamber was deemed as the transmucosal portion. (c) Tumor penetration of Au-Pt-cy5 NPs and Au-Pt@ur-cy5 NPs in 253 J cells, imaged by a confocal microscope from Cy5/DAPI-fluorescence channels; NPs 12 h-incubation. Scale bar: 100 μm. (d) Relative Cy5-fluorescence intensity of the corresponding 253 J cells in panel (c). (e) Tumor penetration of Au-Pt-cy5 NPs and Au-Pt@ur-cy5 NPs in T24 cells, imaged by a confocal microscope from Cy5/DAPI-fluorescence channels; NPs 12 h-incubation. Scale bar: 100 μm. (f) Relative Cy5-fluorescence intensity of the corresponding T24 cells in panel (e). (g-h) Tumor penetration of Au-Pt-cy5 NPs and Au-Pt@ur-cy5 NPs in 253 J/T24 multicellular spheroids, imaged by a confocal microscope from Cy5-fluorescence channel; Z-stack covered the course from the intermediate layer to the bottom layer at 20 μm intervals; NPs 12 h-incubation. Scale bar = 100 μm