Fig. 6.

(A) Schematic illustration of the pHPMA NPs across the mucus layer and intestinal epithelial cells. (B) Fluorescence resonance energy transfer (FRET) intensity of particles prepared with F-insulin and T-pHPMA after incubation in PBS or mucus for different times. The fluorescent intensity of tetraethyl rhodamine isothiocyanate (TRITC) represented the structural integrity of particles. (C) Confocal laser scanning microscopy (CLSM) images of the distribution of F-insulin and T-pHPMA in NPs on E12 cell monolayer from apical to basolateral side. Reprinted from Ref. [77] with permission.