An Injectable Biomaterial for Bone Repair

The primary purpose of this study was to characterize the main features of a BCP-loaded chitosan-GP composite. The two-syringe design improves the storage conditions, facilitates the sterilization procedure and provides an easy-to-use injectable biomaterial, ensuring reproducible properties with minimal manipulation. Rheological measurements confirm that the chitosan- GP/BCP composite retains the thermosensitive properties already described for chitosan-GP hydrogels. At 37°C, the system gels within 10 minutes and reaches sufficient consistency after 30 minutes to prevent the mineral granules from migration into the surrounding tissues in vivo. The compressive force needed for the injection of chitosan-GP/BCP before gelation is approximately 6.6 N, only about 6 times that required for water and much lower than the average force that the majority of adults can exert. Morphology was investigated by environmental scanning electron microscopy (ESEM), which revealed 3-D dispersion of BCP granules embedded in chitosan-GP hydrogel. This open, porous structure affords complete access for body fluids and cells to each mineral granule immediately following implantation. The design using disposable syringes equipped with 16G hypodermic needles described here allows easy in vivo delivery of a fully injectable biomaterial containing porous scaffold that naturally enhances the osteogenic activity recognized for both chitosan and BCP.