Fc-modified exenatide-loaded nanoparticles for oral delivery to improve hypoglycemic effects in mice

To improve the oral efficiency of exenatide, we prepared polyethylene glycol-poly(lactic-co-glycolic acid) (PEG-PLGA) NPs modified with Fc (NPs-Fc) for exenatide oral delivery. Exenatide was encapsulated into the NPs by the w/o/w emulsion-solvent evaporation method. The particle size of the NPs-Fc was approximately 30 nm larger than that of the unmodified NPs with polydispersity indices in a narrow range (PDIs; PDI < 0.3) as detected by DLS, and the highest encapsulation efficiency of exenatide in the NPs was greater than 80%. Fc-conjugated NPs permeated Caco-2 cells faster and to a greater extent compared to unmodified NPs, as verified by CLSM and flow cytometry. Hypoglycemic effect studies demonstrated that oral administration of exenatide-loaded PEG-PLGA NPs modified by an Fc group extended the hypoglycemic effects compared with s.c. injection of the exenatide solution. Fluorescence-labeled NPs were used to investigate the effects of Fc targeting, and the results demonstrated that the NPs-Fc stayed in the gastrointestinal tract for a longer time in comparison with the unmodified NPs, as shown by the whole-body fluorescence images and fluorescence images of the dissected organs detected by in vivo imaging in live mice. Therefore, Fc-targeted nano-delivery systems show great promise for oral peptide/protein drug delivery.