Preparation, Characterization And Biology Properties Research Of Two Kinds Porous Materials For Bone Repair

Porous material has interconnected-network or closed holes structure. Extensive research has been conducted on porous materials application in the bone defect repair because of its structure similar to natural bone. It a tough job to improve the porosity of while maintaining the strength of the scaffold so well to satisfy the clinic application.This study developed a new drug delivery scaffold. Firstly. Porous titanium scaffolds were coated with graphene oxide (GO) by means of electrostatic attraction and physical adsorption. Then gelatin microsphere were prepared and modified with chitosan by physical adsorption, and therefore the positively charged gelatin microspheres can be immobilized on GO coated porous Ti scaffolds. Vancomycin and BMP-2 were encapsulated in the gelatin microsphere. The microsphere loaded scaffolds realized the sustained release of drugs. The results of antibacterial experiments demonstrated that the scaffold has good antibacterial properties. The cell culture tests indicated that the scaffold has good ability to improve cell activity. In vivo experiments indicated that the scaffold could induce bone formation in mice after 3 month implantation.The study also developed a method to prepare porous hydroxyapatite scaffold. In this method, acetone-chloroform was used as volatile solvent; ammonium bicarbonate particles was used as pore forming agent. Organic polymer (polystyrene/high molecular weight polylactic acid, PLLA) solutions were prepared to mix with HA powder and ammonium bicarbonate particles uniformly. Then volatile solvent was evaporated to form polymer/HA composites. After sintering, the porous HA scaffold with a certain strength is formed. When polystyrene was used, it is difficult to complete volatilization and volume shrinkage is not obvious, and therefore the scaffold is brittle. When PLLA is used, the scaffold with high strength is obtained, the strength of the scaffold is highly dependent on the HA powder dispersion, ammonium bicarbonate particle size, and also the sintering profile.