Microstructures and properties of 45S5 bioglass® & BCP bioceramic scaffolds fabricated by digital light processing

Abstract

The porous bioceramic scaffolds require favorable mechanical properties and excellent bioactivity to promote bone repair. In this work, 45S5 bioglass® & biphasic calcium phosphate (BCP) bioceramic scaffolds with a diamond lattice structure (porosity of 70%) were manufactured accurately by digital light processing (DLP). After optimizing the solid loading of bioceramic suspension to 40 vol%, scaffolds with the minimum pore size of 400 µm were fabricated successfully under exposure energy of 12.54 mJ/cm2. In the initial stage of sintering, crystallization occurred during 45S5 bioglass® itself, bioglass also promoted hydroxyapatite (HA) decomposition to tricalcium phosphate (TCP). With extending holding time to 4 h, Si4+ from 45S5 bioglass® diffused into TCP to produce Ca5(PO4)2SiO4, which could enhance the compressive strength of bioceramic scaffolds. Meanwhile, bioglass would assist the growth and roughening of ceramic grains because of the ion-diffusion from bioglass to BCP. However, as holding time extended to 6 h, abnormal grain growth and cracks occurred which would decrease compressive strength. The best value of compressive strength is 1.735 MPa at the holding time of 4 h. 45S5 bioglass® also accelerated ion exchange such as Si4+ and CO32- between bioceramic and SBF solution. This kind of bioceramics may be used as bioactive scaffolds with customizable fine structures and provide potential applications in bone tissue engineering.