Tailoring of mesoporous bioactive glass composite scaffold via thermal extrusion based 3D bioprinting and scrutiny on bone tissue engineering characteristics

In the recent years, mesoporous bioactive glass (MBG) based 3D printed scaffolds have been envisaged widely for bone tissue engineering potential. The earlier reports on 3D printed MBG based scaffolds for bone tissue engineering application are dedicated to pneumatic extrusion, which involves utilization of solvent and tedious process steps for preparation of bio ink. In order to overcome these limitations, the current work aims to develop 3D printed MBG based biomimetic composite scaffold via thermal extrusion process, which is devoid from solvent. It is well known that it is highly challenging to process pure MBG based inorganic/ceramic materials into 3D printed constructs due to lack of flexibility. Therefore, poly(caprolactone) (PCL) which exhibits bio inert nature towards formation of hydroxyapatite is used as the binder in order to impart flexibility during thermal extrusion process. The novelty of the current work lies in optimization of 3D printing parameters in order to fabricate MBG/PCL based composite construct, which mimics the natural bone composition with inorganic to organic ratio of 70:30 with hierarchical pore architecture and evaluation of its bone tissue engineering characteristics, which has not been documented earlier in the best of our knowledge. Through SBF studies, it is revealed that the 3D printed PCL/MBG composite scaffold helps in the formation of hydroxyapatite biomineral, which is lacking in the case of PCL scaffold. The presence of MBG in the PCL matrix is also found to support cellular proliferation and osteogenic differentiation, which is also reflected in terms of calcium mineralization and up regulation of osteogenic genes. This indicates that the 3D printed PCL/MBG composite scaffold mimicking the natural bone composition seems to hold promising potential for bone tissue engineering.