In vitro characterisation of chitosan based xerogels for potential buccal delivery of proteins

Chitosan and thiolated-chitosan based xerogels have been prepared by lyophilising aqueous gels of the polymers incorporating glycerol, d-mannitol and BSA with an annealing process. Analytical characterisation was by circular dichroism, infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Swelling capacities of 1110 ± 23.3% and 480 ± 18.2% were obtained for the chitosan and TG-chitosan xerogels respectively. Thiolation caused improved in vitro mucoadhesive properties by demonstrating peak adhesive force of 4.5 ± 0.7 and 5.8 ± 0.2 N, and total work of adhesion of 6.5 ± 1.0 and 19 ± 0.8 mJ for chitosan and thiolated-chitosan xerogels respectively. In vitro drug dissolution studies using Bradfordʹs assay showed BSA release of 91.5 ± 3.7% and 94.4 ± 7.3% from the chitosan and thiolated-chitosan xerogels respectively. These results demonstrate the potential of developing lyophilised thiolated-chitosan xerogels with optimised mucoadhesion characteristics for buccal mucosa delivery of protein based drugs.