Fig. 9.

In vitro permeability studies. a) Cumulative permeability of insulin across Caco-2/HT29-MTX co-cultures grown in Transwell® permeable supports after incubation with insulin-loaded UnTHCPSi, UnTHCPSi@LNPs, and UnTHCPSi@LNPs-Fc for 120 min. The experiments were conducted in HBSS–HEPES at 37 °C, from the apical (pH 6.5) to the basolateral (pH 7.4) side of the Transwell® supports. b) Apparent permeability coefficients (P_app × 10⁻⁶ cm/s) of insulin across Caco-2/HT29-MTX monolayers calculated from the drug permeation profiles. For a) and b), results are presented as mean ± s.d. of three different samples ($n$ = 3). Two-way ANOVA was used for the statistical analyses of the values measured at the last time point, followed by the Bonferroni post hoc test. The level of significant differences was set at probabilities of *$p<$ 0.05, **$p<$ 0.01, ***$p<$ 0.001, and ****$p<$ 0.0001. c) TEM images of flat embedded ultra-thin Caco-2/HT29-MTX monolayers after 120 min of incubation with buffer, UnTHCPSi, UnTHCPSi@LNPs, and UnTHCPSi@LNPs-Fc for the in vitro permeability studies. The scale bars represent 1 μm.