Preparation of poly(lactic-co-glycolic acid) and chitosan composite nanocarriers via electrostatic self assembly for oral delivery of insulin

•The composite nanocarriers prepared from PLGA and chitosan have been described.•The as-prepared composite nanocarriers have been used to oral delivery of insulin.•An effective hypoglycemic effect with PA% and FR% at 7.22% and 7.77% has been obtained.

To improve insulin bioavailability and overcome multiple barriers for oral delivery of insulin, the composite nanocarriers (PLGA/FA-CS) prepared from poly(lactide-co-glycoside) (PLGA) and folic acid modified chitosan (FA-CS) were fabricated via electrostatic self-assembly method. The resultant composite nanocarriers exhibited low cytotoxicity against HT-29 cells and excellent stability against protein solution. The chemical stability of loaded insulin against digestive enzyme were established in presence of simulated gastric fluid (SGF) containing pepsin and simulated intestinal fluid (SIF) containing pancreatin, respectively. The uptake behavior of HT-29 cells was evaluated by confocal laser scanning microscope. After oral administration to the diabetic rats, an effective hypoglycemic effect was obtained compared with subcutaneous injection of insulin. This work suggests that the as-prepared composite nanocarriers may be a promising drug delivery system for oral administration of insulin and other biomacromolecules.