Innovative pharmaceutical systems based on chitosan and its derivatives

Various chemical modifications of chitosan have been studied in order to improve its solubility and applications. Attempts to introduce positive charge on the polymer chain appeared to be rational. Moreover, the introduction of thiol groups on the unsubstituted primary amino groups of chitosan-ammonium quaternary conjugates, led to water-soluble thiomers. The thiol groups are supposed to give exchange reactions with disulfide bonds within the mucus or oxidation reactions with cysteine-rich subdomains of mucus, both resulting in the formation of disulfide bonds, which improve the polymer mucoadhesivity. Nanoparticles prepared from this type of chitosan derivatives were supposed to be themselves mucoadhesive and apt to make nanocarriers for drug delivery. In the light of the above information, in this thesis, different pharmaceutical applications of chitosan and its derivatives, and nanoparticles based on these polymers have been evaluated.