FcRn-targeted Pluronic F127-Poly (L-lactic Acid) polymersomes for oral insulin delivery

The intestinal epithelium barrier is one of the main factors limiting the bioavailability of oral insulin delivery systems. Neonatal Fc (fragment crystallizable) receptor (FcRn) is highly expressed in the intestinal epithelium, which can bind specifically to the Fc fragments of IgG in a pH-dependent manner and thus improve the transepithelial transport of carriers modified by IgG Fc or Fc domain-binding peptides (FcBP) ligand. Thus, FcBP ligand was attached to Pluronic F127-polylactic acid polymersomes by using the biotin-avidin bridging technology to obtain FcRn-targeted FcBP-F127-PLA polymersomes. Insulin (INS) was loaded successfully into FcBPF127-PLA with the loading efficiency of 12.01 %. The transepithelial transport experiments on Caco-2 cells using Coumarin-6 (C-6) as a fluorescence probe showed that the cumulative permeability percentage and apparent permeability coefficient (Papp) of the FcBP-F127-PLA/C-6 group was 1.7 and 1.8 times that of PLA-F127-PLA/C6 group after 2 h of incubation, respectively. FcBP ligand density of FcBP-F127-PLA played a role on their transepithelial transport ability and 10%FcBP-F127-PLA with 10 % FcBP molar content was found to be the best. The in vivo hypoglycemic results showed that the relative pharmacological bioavailability (PAR%) of the oral 10%FcBP-F127-PLA/INS group was 43.6 %, which was 1.27 times that of the PLA-F127-PLA/INS group. Therefore, FcBP-F127-PLA polymersomes could be a promising carrier of the oral insulin delivery.