Poly(alpha-hydroxyl acids) hydroxyapatite porous composites for bone-tissue engineering. I. Preparation and morphology

Tissue engineering has shown great promise for creating biological alternat ives for implants. In this approach, scaffolding plays a pivotal role. Hydr oxyapatite mimics the natural bone mineral and has shown good bone-bonding properties. This paper describes the preparation and morphologies of three- dimensional porous composites from poly(L-lactic acid) (PLLA) or poly(D,L-l actic acid-coglycolic acid) (PLCA) solution and hydroxyapatite (HAP). A the rmally induced phase separation technique was used to create the highly por ous composite scaffolds for bone-tissue engineering. Freeze drying of the p hase-separated polymer/HAP/solvent mixtures produced hard and tough foams w ith a co-continuous structure of interconnected Forts and a polymer/HAP com posite skeleton. The microstructure of the pores and the walls was controll ed by varying the polymer concentration, HAP content, quenching temperature , polymer, and solvent utilized. The porosity increased with decreasing pol ymer concentration and HAT content. Foams with porosity as high as 95% were achieved. Pore sizes ranging from several microns to a few hundred microns were obtained. The composite foams showed a significant improvement in mec hanical properties over pure polymer foams. They are promising scaffolds fo r bone-tissue engineering. (C) 1999 John Wiley & Sons, Inc.