Vat photopolymerization and characterization of porous bioactive glass-derived scaffolds for bone repair

In the field of Bone Tissue Engineering, the primary focus has been on improving the regeneration of bone tissue using biomaterials. Digital Light Processing-based vat photopolymerization, also known as stereolithography, is an Additive Manufacturing technique that shows an outstanding potential for fabricating porous scaffolds. This method offers notable benefits including the capacity to generate highly interconnected and porous structures with high reproducibility. This MS thesis work focuses on the printing – carried out in the company Lithoz GmbH (Austria) – and analysis of BG-1d scaffolds, which had a complex microstructure obtained from micro-CT scanning of a polymeric sponge used as the input to the printing system. BG-1d is a bioactive silicate glass that has already shown success in regenerating bone tissue in both animal and human subjects. Glass powder was analysed from a thermal viewpoint by hot-stage microscopy and differential thermal analysis for optimizing the choice of the sintering temperature for scaffolds. X-ray diffraction was made to analyse the microstructure (crystalline–phases) both in powder and in scaffolds. Scanning electron microscopy and computed tomography were utilized for the analysis of the morphology, pore size distribution and strut thickness of the scaffolds. The potential of the printing system was pushed to the limit obtaining scaffolds with >95 vol.% porosity. Mechanical tests were conducted to experimentally evaluate scaffold properties under compressive loads. Additionally, permeability test was executed to determine the intrinsic permeability of the scaffolds through acoustic experimental measurements. Lastly, in-vitro bioactivity tests in simulated body fluids were performed to assess scaffold bioactive behaviour (apatite-forming ability). Moreover, some scaffolds were fabricated for an in-vivo study to be conducted in the frame of a collaboration with Professor D.U. Tulyaganov (TTPU, Uzbekistan).