Batista, PatríciaCastro, Pedro M.Madureira, Ana RaquelSarmento, BrunoPintado, Manuela2021-11-032021-11-032021-11-012076-3417http://hdl.handle.net/10400.14/35791Background: Biological molecules such as therapeutic proteins and peptides have provided ample opportunities for further improvements in health and wellbeing. However, such biomacro-molecules face stability challenges regarding premature processing and digestion, whenever any enteric delivery route is considered. Hence, oral guar films entrapping peptide-containing chitosan microparticles have been developed as a new delivery system to carry and protect therapeutic relaxing peptides. Results: The composite films were characterized regarding physicochemical properties using FTIR as well as peptide encapsulation efficiency, cytotoxicity, and peptide permeability through buccal and intestinal cell-based models. The composite films with 0.18% (w/w) of peptide demon-strated ca. 0.63% of peptide loading efficiency into the chitosan microparticles and to be safe for buccal and intestinal epithelial cells up to 24 h of contact. The permeability assays through TR146 cells to mimic buccal mucosa epithelium and Caco-2/HT29-MTX to mimic duodenum conditions showed that the incorporation of peptide chitosan microparticles into guar-gum oral films offered a faster permeability, when compared with the free peptide and peptide-chitosan-microparticles-loaded chitosan. Conclusion: This study suggests that peptide-loaded chitosan microparticles into guar-gum oral films might be a promising carrier for enhancement of the buccal and intestinal absorption of a relaxing peptide.engBioactive peptidesChitosanOral delivery systemOral filmsjournal article10.3390/app1121984985117747373000726930000001