Synthesis and characterization of novel bioadhesive material thiolated chitosan

The use of mucoadhesive thiolated polymers as the carriers can improve the adsorption of drugs by prolonging the residence time on the nasal mucosa on the basis of the formation of disulphide bonds between thiol groups on polymer and cysteine-rich domains of mucus glycoproteins. In this study, a novel thiolated polymer, N-acetyl-L-cysteine-g-chitosan conjugate (CS-NAC) was synthesized and characterized. Swelling and mucoadhesive properties of CS-NAC conjugates were evaluated in vitro. The cytotoxicity of CS-NAC conjugates was measured on L-929 mouse fibroblast cells by utilizing MTT method. The obtained CS-NAC conjugate displayed the most content of thiol group (589.3 +/- 38.6) mu mol/g. The conjugates exhibited a fast swelling behavior in comparison to the unmodified chitosan. The mucoadhesive properties of CS-NAC conjugate showed more than 30-fold increase in mucoadhesion time and 3-fold increase in adhesive force versus the unmodified chitosan. Moreover, CS-NAC did not cause a significant increase in cytotoxicity. Therefore, the novel thiolated chitosan is a promising potential bioadhesive material.