Carrier preparation
Conformational change of the rhBMP-2 due to sterilization was avoided by mixing the rhBMP-2 solution with a powder gel composite to a final concentration of 1 mg/ml rhBMP-2. The in situ mixing process is a method used to generate an rhBMP-2 loaded injectable carrier by mixing the powder gel and the porous spherical particles for loading rhBMP-2.
In other words, one syringe contained porous β-TCP microspheres and the other syringe held the HA-based powder-gel containing 1 mg/ml rhBMP-2, and the relative weight ratio of the materials was 1:9. These two syringes were interconnected through a 2-way connector and 30 cycles of piston movement of each syringe were performed to ensure that the mixture was homogeneous. Collectively, β-TCP microspheres and HA were used as an rhBMP-2 carrier in this study.