Biodegradable stereolithography resins with defined mechanical properties

Solid Freeform Fabrication methods based on photopolymerization (e.g. stereolithography SLA, digital light processing DLP, two photon absorption TPA) offer the possibility to shape complex structures with high feature resolution and excellent surface quality. If these methods are to be used for applications in regenerative medicine, new photopolymers with defined functional and mechanical properties have to be developed. For applications in the field of bone replacement materials scaffolds with defined external and internal geometry are required. The ideal pore size is between 200 and 500μm which is an achievable minimum feature resolution for lithographic methods. Further requirements are non-toxicity of the scaffolds which requires proper selection of monomers and photoinitiators. Using acrylate modified gelatine as crosslinker, the final photopolymer can be made biodegradable by enzymatic mechanisms. To further increase the elastic modulus, hydroxyapatite can be used as filler material. Using these polymers cellular scaffolds have been built and osteoblast like cells adhered and proliferated excellently. The obtained elastic moduli can range from 0,1 MPa to 8.000MPa.