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.