Chitosan microspheres/nano-hydroxyapatite/collagen/polylactide composite

Chitosan microspheres (CMs) loaded with bovine serum albumin (BSA) were prepared by an emulsion-ionic crosslinking method in the presence of tripolyphosphate (TPP). Porous CMs/nano-hydroxyapatite/collagen/polylactide (CMs/nHAC/PLA) composite was developed by thermally induced phase separation. The properties of the CMs and composite were investigated by SEM, laser particle size analyzer, mercury porosimeter and universal testing machine. The results indicate that the CMs are spherical in shape, with a regular surface. The diameters of the CMs are in the range of 20-50μm. With the increase of initial BSA dosage, the loading capacity is also increased from 0.78% to 2.74%, whereas the encapsulation efficiency is decreased from 86.9% to 78.4%. Controlling the CMs dosage to be not higher than 30% on a PLA weight basis, the CMs can distribute perfectly in the whole CMs/nHAC/PLA composite. The total porosity of the porous composite is over 83.1%. The pore diameter is about 100-200μm, and the compressive strength is about 1-2 MPa. This porous composite is a promising material for non-loaded bone implants and tissue engineering scaffolds.