Biodegradable and redox-responsive chitosan/poly(L-aspartic acid) submicron capsules for transmucosal delivery of proteins and peptides.

The development of peptides and proteins is hampered by their rapid clearance in liver and other body tissues by proteolytic enzymes, so these drugs are difficult to administer except for the injection. Here, we designed and fabricated a novel biodegradable and redox-responsive submicron capsules through the layer-by-layer technique with poly(L-aspartic acid) and chitosan for transmucosal delivery of proteins and peptides. TEM graphs reveal that the intact submicron capsules were obtained and the shell of submicron capsules was about 40 nm. The mucoadhesion test indicates that the adsorption amount of the mucin could achieve up to 96.2 μg per 2 mg. The cell viability test shows that all types of submicron capsules had good cytocompatibility and the cell viability was above 90 %. As a drug model, the insulin could be loaded in the submicron capsules, and the loading efficiency was about 5 %. The release amount of insulin could be regulated by the levels of GSH. Therefore, the mucoadhesive submicron capsules as vehicles have a potential for the mucosal delivery (e.g. nasal and buccal) of therapeutic peptide and protein drugs.