Preparation of an injectable modified chitosan-based hydrogel approaching for bone tissue engineering.

Abstract This research aimed to design an injectable chitosan-based hydrogel for bone tissue engineering. To this end, chitosan should not only be soluble in water but also be thixotropic. Therefore, it can be used as an injectable liquid that can form a hydrogel under physiological conditions. Accordingly, chitosan was modified with carboxymethyl chloride and the resultant carboxymethyl chitosan (CMCTS) was conjugated to α-cyclodextrin (α-CD) to yield CMCTSCD. The α-CD conjugation improved the water solubility and the hydrophobic cavities to function as crosslinking points by forming an inclusion complex with poly(ethylene glycol) (PEG). The optimum mole ratio of α-CD (as CMCTSCD) to PEG was found to be 2 to 4 with a threading number of ~2.5. The sol-to-gel transition was formed within 450 ± 10 min. The interconnecting porous structure of the gel was observed by scanning electron microscope. Therefore, CMCTSCD/PEG is a potential novel design that can be used as an injectable hydrogel for bone tissue engineering.