A comparison of the degradation behaviour of 3D printed PDLGA scaffolds incorporating bioglass or biosilica.

Silica incorporation into biomaterials, such as Bioglass and Si-substituted calcium phosphate ceramics has received significant attention in bone tissue engineering over the last few decades. This study aims to explore the dissolution behaviour of natural biosilica isolated from a freshwater diatom, Cyclotella meneghiniana, that has been incorporated into 3D printed poly (DL-lactide -co - glycolide) (PDLGA) scaffolds using extrusion and additive manufacturing. In the study, two different dry weight percentage (1 wt% & 5 wt%) of diatom-silica were incorporated into PDLGA scaffolds that were then degraded in phosphate buffered saline (PBS) cell free media. In addition, pure PDLGA scaffolds and 5 wt% Bioglass scaffolds were used as control groups. The degradation study was performed over 26-weeks. The release rate of Si4+ ions from diatom-PDLGA scaffolds was found to increase exponentially with respect to time. The compressive strength of scaffolds was also measured with the Diatom-PDLGA scaffolds found to maintain their strength for longer than either pure PDLGA scaffolds or 5 wt% Bioglass scaffolds. 13C NMR data showed that diatom biosilica containing scaffolds had less degradation than pure or bioglass-containing scaffolds at comparable time-points. Overall, the Diatom-PDLGA scaffolds were found to have more desirable physiochemical properties for bone repair compared to Bioglass.