  Three-dimensional Mesoporous bioactive glasses (MBGs) scaffolds has been
widely considered for bone regeneration purposes and additive manufacturing
enables the fabrication of highly bioactive patient-specific constructs for
bone defects. Commonly, this process is performed with the addition of
polymeric binders that facilitate the printability of scaffolds. However, these
additives cover the MBG particles resulting in the reduction of their
osteogenic potential. The present work investigates a simple yet effective
phosphate-buffered saline immersion method for achieving polyvinyl alcohol
binder removal while enables the maintenance of the mesoporous structure of MBG
3D-printed scaffolds. This resulted in significantly modifying the surface of
the scaffold via the spontaneous formation of a biomimetic mineralized layer
which positively affected the physical and biological properties of the
scaffold. The extensive surface remodeling induced by the deposition of the
apatite-like layer lead to a 3-fold increase in surface area, a 5-fold increase
in the roughness, and 4-fold increase in the hardness of the PBS-immersed
scaffolds when compared to the as-printed counterpart. The biomimetic
mineralization also occurred throughout the bulk of the scaffold connecting the
MBGs particles and was responsible for the maintenance of structural integrity.
In vitro assays using MC3T3-E1 pre-osteoblast like cells demonstrated a
significant upregulation of osteogenic-related genes for the scaffolds
previously immersed in PBS when compared to the as-printed PVA-containing
scaffolds. Although the pre-immersion scaffolds performed equally towards
osteogenic cell differentiation, our data suggest that a short immersion in PBS
of MBG scaffolds is beneficial for the osteogenic properties and might
accelerate bone formation after implantation.
