In situ Crosslinkable Thiol-ene Hydrogels Based on PEGylated Chitosan and β-Cyclodextrin

Novel β-Cyclodextrin incorporated injectable hydrogels employing PEGylated chitosan as bio-based hydrophilic matrix have been fabricated via thiol-ene reaction. As thiol bearing polymer counterpart of hydrogel precursors, native chitosan was firstly modified with polyethylene glycol groups to increase its water solubility and bioinertness and then decorated with thiol groups to facilitate thiol-ene crosslinking with acryloyl-modified β-cyclodextrin. A series of hydrogels with varying amounts of acryloyl β-CD and PEGylated chitosan feed were synthesized with high efficiency under mild aqueous conditions. The resulting hydrogels were characterized by equilibrium swelling, structural morphology and rheology. These materials were investigated as controlled drug release platforms by employing a poorly water soluble anti-inflammatory drug diclofenac as model compound. Benefiting from the inclusion complex formation of the drug with β-CD groups in gel interior, prolonged release profiles were maintained. The total drug absorption and release of hydrogels were shown to be dependent on the amount of β-CD in gel matrix. These hydrogels combined efficient crosslinking and β-CD incorporation into clinically important chitosan scaffold and might have potential applications as injectable drug reservoirs such as in regenerative tissue engineering.