Chitosan nanocapsules: a new carrier for nasal peptide delivery

This work describes the preparation and characterization of chitosan (CS)-coated oil nanodroplets (named CS nanocapsules) as well as the evaluation of their potential for enhancing the nasal absorption of peptide drugs, using salmon calcitonin (sCT) as a model peptide. CS nanocapsules were obtained by the solvent displacement technique. The presence of the CS coating in the nanocapsules was noted by transmission electron microscopy and confirmed by the increase in their size and the inversion in the zeta potential (from negative to positive). The association efficiency of sCT to the nanocapsules was high and affected by the presence of the CS coating. After nasal administration to rats, CS nanocapsules led to a hypocalcemic effect significantly enhanced and prolonged in comparison to that corresponding to the uncoated sCT-loaded oil nanodroplets (named also uncoated nanoemulsion) or to the sCT aqueous solutions containing CS. Consequently, the results highlight the critical role of the CS coating in enhancing the transport of the associated peptide and, hence, the potential utility of CS nanocapsules for nasal peptide delivery.