Synthesis and Evaluation of Boronated Chitosan as a Mucoadhesive Polymer for Intravesical Drug Delivery

This work reports the synthesis of boronated chitosan by reacting it with 4-carboxyphenylboronic acid to improve its mucoadhesive properties. Three products with differing extent of boronate conjugation were synthesized and characterized using 1H NMR, FT-IR, and UV-Vis spectroscopy, and the potential of these polymers to extend the residence time of loaded model drug in the bladder was investigated. 1H NMR and ninhydrin test were used to evaluate the extent of chitosan modification. Mucoadhesive properties were evaluated using ex vivo flow-through technique on porcine bladder mucosal tissue combined with fluorescent microscopy, where fluorescein sodium was used as a model drug. The mucoadhesive properties of these polymers on porcine bladder mucosa were also studied using tensile test. There was good correlation in the mucoadhesive profiles of the polymers using the flow through and tensile techniques. The degree of chitosan modification had a remarkable influence on their mucoadhesive behavior, and greater mucoadhesion was observed with increased degree of boronation. These chitosan derivatives have the potential as intravesical drug delivery systems to improve bladder therapy.