Selective Laser Sintered Poly(L-Lactide)/Carbonated Hydroxyapatite Nanocomposite Scaffolds: A Bottom-up Approach

The main objective of this research is to study the feasibility of using the selective laser sintering (SLS) technology to fabricate 3D porous scaffolds from poly(L-lactide) (PLLA) and poly(L-lactide)/carbonated hydroxyapatite (PLLA/CHAp) nanocomposite for bone tissue engineering applications. There are great demands for tissue engineering (TE) and ideal tissue engineering scaffolds should possess physical, mechanical, chemical and biological properties to fulfill the requirements for tissue regeneration. These properties basically depend on two key factors; namely, material composition and scaffold architecture. To address the first issue, biocomposites seem to be a better choice than single matrix. In this study, a biocomposite, which consists of PLLA microspheres filled with CHAp nanoparticles, is developed. PLLA is chosen because it is an FDA-approved, biocompatible and biodegradable polymer which has been widely used in many biomedical applications. Meanwhile carbonated hydroxyapatite is a promising material for bone substitution as it is bioresorbable and also more bioactive in vivo than stoichiometric hydroxyapatite. In terms of scaffold architecture, modern rapid prototyping (RP) technologies such as stereolithography apparatus (SLA), fused deposition modeling (FDM), 3D printing and SLS offer excellent flexibility. However, materials used for SLA are typically acrylics and epoxies, which are non-biodegradable. At present, only very limited choices of materials are available for FDM because the materials have to be in the form of filament. 3D printing is also limited by the availability of suitable binders to meet the biological and strength requirements of tissue engineering scaffolds. In contrast, SLS has already been used to produce porous poly(εcaprolactone) (PCL) bone tissue engineering scaffolds based on actual model of minipig and human condyle (Partee, Hollister et al. 2006), therefore it has a great potential for tissue engineering scaffold fabrication and has been chosen for this project. However, SLS has been developed primarily for industrial applications. At present, it is not financially viable to process most biopolymers or their composites in commercial SLS machines because the amount of material required is quite substantial and the costs of biopolymers are very high.