The term chitosan (CS) refers to a family of aminopolysaccharides derived from chitin. Among other properties, CS is nontoxic, mucoadhesive and can be used for load and transport drugs. Given these and other physicochemical and biological properties, CS is an optimal biopolymer for the development of transmucosal drug delivery systems, as well as for the treatment of pathologies related to mucosal dysfunctions. Mucins are glycoprotein macromolecules that are the major components of mucus overlaying epithelia. CS interacts with mucin and adsorbs on and changes the rheology of mucus. However, CS and mucins denote families of polymers/macromolecules with highly variable chemical structure, properties, and behavior. To date, their interactions at the molecular level have not been completely unraveled. Also, the properties of complexes composed of CS and mucin vary as a function of the sources and preparation of the polymers. As a consequence, the mucoadhesion and drug delivery properties of such complexes vary as well. The breadth of this review is on the molecular interactions between CS and mucin. In particular, in vitro and ex vivo characterization methods to investigate both the interactions at play during the formation of CS-mucin complexes, and the advances on the use of CS for transmucosal drug delivery are addressed.

Aims: To investigate the cytotoxicity and bioactivity of several pulpotomy materials: Biodentine (Septodont, Saint‐Maur‐des‐Fosses, France) MTA (Angelus, Londrina, PR, Brazil), Theracal LC (Bisco Inc., Schamburg, IL, USA) and IRM (Dentsply DeTrey GmbH, Konstanz, Germany), after contact with stem cells isolated from human exfoliated primary teeth (SHEDs).Methodology: SHEDs were cultured in the presence of the eluates of various pulpotomy materials for 24, 48 and 72 h. Cell viability was determined by mitochondrial dehydrogenase enzymatic (MTT) assay. Apoptosis and changes in cell phenotype were evaluated by flow cytometry. Also, an in vitro scratch wound‐healing assay was used to determine their effects on cell migration. To assess cell morphology and attachment to the different pulpotomy materials, SHEDs were directly seeded onto the material surfaces and analysed by scanning electron microscopy (SEM). Finally, the deposition of a calcified matrix in presence of these materials was verified by Alizarin Red staining. Statistical analysis was performed with analysis of variance and Bonferroni or Tukey post‐test (α = 0.05).Results: Cell viability in the presence of Biodentine eluates was significantly higher to that obtained using complete medium alone (control; P < 0.01) and was also significantly higher than using MTA Angelus from 48 h of incubation (P < 0.01). However, Theracal LC and IRM were associated with low rates of cell viability (P < 0.001). Similar results were obtained in an apoptosis assay. In addition, SHEDs maintained their mesenchymal phenotype in all conditions although their capacity to migrate was higher in the presence of Biodentine. SEM studies revealed a suitable proliferation rate, cell spreading and attachment, especially when using Biodentine and MTA Angelus discs. Finally, Biodentine eluates significantly induced calcified matrix deposition from 7 days of culture (P < 0.01).Conclusions: Biodentine exhibited better cytocompatibility and bioactivity than MTA Angelus, Theracal LC and IRM.