Engineering stiffness in highly porous biomimetic gelatin/tertiary bioactive glass hybrid scaffolds using graphene nanosheets

Class II organic-inorganic hybrid materials have emerged as a promising replacement for the conventional bioactive glass particle-polymer composite biomaterials. Although these materials benefit from several advantages, such as controlled congruent degradation and improved cell response compared with the conventional composites, they become brittle when the inorganic-to-organic ratio exceeds an optimum value, rendering them unsuitable for tissue engineering applications. Here, a series of hybrid composite scaffolds were prepared from gelatin, tertiary bioactive glass and graphene oxide (GO) using a sol-gel/gas foaming technique. This study shows that rather than increasing the inorganic concentration to increase the mechanical stiffness, a small amount of GO (1 and 2 wt%) can be used to remarkably improve the Young's modulus of hybrid materials, by about 200%, without deteriorating the strain to failure. The hybrid scaffolds underwent a linear biodegradation, and a remarkable bioactivity reflected in a thick layer of hydroxyapatite formed on their surfaces after 14 days of immersion in carbonate buffered Dulbecco's modified Eagle's medium. The excellent biocompatibility of these scaffolds towards human adipose-derived mesenchymal stromal cells was confirmed in vitro. GO-doped organic-inorganic hybrid composite scaffolds may be ideal materials for a range of tissue engineering applications such as interface and non-load bearing bone tissue engineering.