[Preparation of functional chitosan thermosensitive hydrogel for slow release both rhBMP-2 and chlorhexidine]

The chitosan thermosensitive hydrogel is liquid at room temperature but gels rapidly when heated to body temperature. This hydrogel are wildly used for cell encapsulation, drug delivery or tissue-engineered scaffolds. The system can sustain the release of macromolecules over a period of several hours to a few days. However, with low-molecular-weight compounds, the release is generally completed within 24 h. To prepare a functional chitosan thermosensitive hydrogel for slow release both broad-spectrum antibiotic chlorhexidine and growth factor recombined human bone morphogenetic protein-2 (rhBMP-2), The beta-cyclodextrin was used to prepare an inclusion complex with chlorhexidine, and then the latter was incorporated into the chitosan thermosensitive hydrogel system. Simultaneously, rhBMP-2 was added into the hydrogel system. By HAAKE viscosity measuring instrument, we contrasted the viscoelastic properties of system with or without objective factors. And the in vitro release kinetics of chlorhexidine and rhBMP-2 was investigated by HPLC (high performance liquid chromatography) and ELISA (enzyme-linked immunosorbent assay) respectively. The results showed that the addition of chlorhexidine/beta-cyclodextrin inclusion complex to the thermosensitive solution did not change the gelling behavior of the thermosensitive system. Further, the in vitro release profiles demonstrated that the release rate of chlorhexidine and rhBMP-2 from hydrogel became slower, controlled delivery over at least 1 month. By first preparing chlorhexidine/beta-cyclodextrin inclusion complex, and then mixing the IC and rhBMP-2 into the chitosan thermosensitive hydrogel, a functional chitosan thermosensitive hydrogel system with ability of slow release both rhBMP-2 and chlorhexidine is successfully made.