Chitosan-based thermosensitive hydrogel entrapping calcein for visualizing localized drug delivery

Localized drug delivery (LDD) is one of the unmet needs for the treatment of various localized medical conditions like infections, cancer, pain, etc. Several hydrogel-based modalities are now being developed for drug delivery, tissue regeneration, treating diseases, and postoperative physiological response. Local anesthetics are one of the most widely used medicine in pain management. Unfortunately, there are several drawbacks associated with local anesthetics such as repeated dosing, short duration of action, and dose dumping. However, some drug carriers based on nanoparticles (NPs) have been used to overcome the problems associated with local anesthetics, but these NPs exhibit minimal residence time at the injected site. In the current study, we report a thermosensitive hydrogel based on chitosan and β-glycerophosphate as a cross-linker can be a promising approach for sustained and localized drug delivery drugs. These hydrogels exhibited a phase transition from sol (4 °C) to gel at physiological temperature (37 °C) that can prolong the half-lives by sustained release of the local anesthetics. The hydrogel entrapping calcein (hydrophilic model drug) exhibited sustained release, and by utilizing its fluorescence, its release from the gel was visually monitored in real-time.