Development of Nanocomposite Scaffolds for Bone Tissue Engineering

Abstract

Abstract Nanocomposite scaffold materials based on biodegradable polymers, as there are poly(3‐hydroxybutyrate (PHB), poly(hydroxybutyrate‐ co ‐hydroxyvalerate) (PHBHV) and polycaprolactone (PCL), and nanocrystalline hydroxyapatite (HA) have been developed for the application as biomimetic bone substitution materials and materials for the tissue engineering of bone. Parameters like pore size, shape and interconnectivity are optimized to facilitate the formation of new bone. In this paper we describe a manufacturing method for compact nanocomposite scaffolds as well as for 3‐dimesional porous scaffolds. Nanocomposite scaffolds consisting of PHB and HA needles or PHBHV and HA spheres, respectively, exhibit a very good filler dispersion even at 20 wt% loading. Smaller nanoparticles (needles) slightly tend to develop more agglomerates due to higher van der Waals forces of attraction compared to the larger spherical nanoparticles which were more uniformly dispersed. To produce porous structures, templates consisting of sugar and NaCl grains of varying grain size were used. In freeze‐drying and particulate leaching processes smaller grain sizes resulted in pores with 46 to 70 µm, whereas grain sizes of more than 400 µm resulted in pores with 300 to 600 µm in diameter. The application of polymer solutions with a concentration of 5% (w/v) resulted in larger pore sizes compared to solutions of 10% (w/v). By the application of the melt infiltration technique to PCL, the resulting pore size was less influenced by the concentration of the polymer solution. It can be demonstrated that these techniques are suitable for the fabrication of nanocomposite scaffolds with uniform filler dispersion and porosity up to 98%.