Fig. 2

a Schematic illustration for silicon tube rotation test. b W-LPNs and pW-LPNs diffusion through porcine mucus. c Concentration-to-size nanoparticle distribution before (blue curves) and after (black curve) 30 min incubation. d Confocal images showing pW-LPN diffusion and penetration through the mucus secreted by HT29-MTX-E12 cells. Double fluorescent-labeled nanoparticles with TRITC-labeled pHPMA (red signal) and FITC-labeled nanoparticles (green signal) were applied to the cell surface for 1 h. Sequential stacked xy-plane (rotation angles: x = 80°, y = 18°, z = 270°) in z-series at 10-μm intervals parallel to cell growth on glass bottom