Novel thermally sensitive pH-dependent chitosan/carboxymethyl cellulose hydrogels

Temperature-responsive polymers are attractive candidates for applications related to injectable delivery of biologically active therapeutics. In this study, a novel approach to provide thermally sensitive neutral solutions based on chitosan/carboxymethyl cellulose (Ch/CMC) combinations is described. The potential of thermosensitive Ch/CMC as a biomaterial is evaluated for the culture of chondrocytes, with the goal of using the Ch/CMC polymer as an injectable matrix/cell therapeutic. These formulations possess a physiological pH and can be held as liquid below room temperature for encapsulating living cells. At body temperature they form monolithic gels, thus injected in vivo, the liquid formulations turn into gel implants in situ. The sols/gels have been thoroughly characterized for rheology and morphology analysis. The use of Ch/CMC aqueous solutions as gelling systems is a new discovery of a new family of thermosetting gels highly compatible with biological compounds.