Processing and characterisation of novel bioceramics for load bearing applications

PhD ThesisThe use of bioceramic materials for the repair and regeneration of injured or diseased parts of the musculoskeletal system is a longstanding area of interest. However, the possibility to extend their range of applications, particularly for load-bearing bone defects and shape them into custom-built geometries is still an open challenge. Beyond the state of the art, this research work focused on the processing and characterisation of eight novel silicate, phosphate and borate glass formulations (coded as NCLx, where x=1 to 8), containing different oxides and in diverse molar percentages. The glass frits were provided by GTS Ltd (Sheffield, UK) along with apatite-wollastonite (AW), used as comparison material. In the first part of the work glass powders were characterised in terms of physico-chemical and biological properties. Subsequently, the glass powders were processed in form of dense bulk materials, and their sintering and mechanical behaviour was evaluated. On the basis of the biocompatibility data, assessed using rat osteoblasts, three formulations were selected for further characterisation. In vitro bioactivity testing using simulated body fluid showed that after 7 days of incubation the three materials, and NCL7 in particular, showed the formation of globular shape apatite precursor precipitates, indicating the bioactive behaviour of these glasses. In the last part of the study, 3D porous structures were manufactured via a binder jetting, powder-based 3D printing technology. The sintered 3D printed parts exhibited architecture and mechanical property values similar to those of AW. In addition, the in vitro biocompatibility indicated a biological positive response with a cell viability comparable to AW after 7 days. The research overall has processed and characterised a range of novel bioceramic formulations, and demonstrated the potential and effectiveness of the 3DP strategy to manufacture highly reproducible ceramic-based structures