Incorporation of Cu-Containing Bioactive Glass Nanoparticles in Gelatin-Coated Scaffolds Enhances Bioactivity and Osteogenic Activity

Bioactive glass scaffolds (BGS) of 45S5 composition exhibit desired bioactivity, osteogenesis, and angiogenesis potential, being promising biomaterials for bone repair/regeneration. Natural polymer-based coatings, e.g., gelatin coating, are effective to enhance the mechanical properties of BGS. However, the presence of a coating may reduce the bioactivity and osteogenesis activity of the scaffolds. To address the issue of reduced osteogenic properties induced by polymer coatings, in this study, we incorporated Cu-containing bioactive glass nanoparticles (Cu-BGN: 95SiO2-2.5CaO-2.5CuO, in mol %), as bioactive fillers, into the gelatin coating. The bioactivity (apatite-forming ability) of the gelatin coated BGS was improved after the incorporation of Cu-BGN in the coating. Hydroxyapatite could form on the Cu-BGN/gelatin nanocomposite coated BGS within 1 day of immersion in simulated body fluid. The osteogenic activity as indicated by the ALP activity of MC3T3-E1 cells on the coated BGS was also significantly enhanced after the incorporation of Cu-BGN. In addition, the incorporation of Cu-BGN in the coating did not affect the highly porous and interconnected pore structure of BGS while the mechanical improvement induced by the gelatin coating remained after the addition of Cu-BGN. The attachment of MC3T3-E1 cells on the scaffolds was not influenced by the presence of Cu-BGN in the gelatin coating, while the cell proliferation was enhanced. In conclusion, the incorporation of bioactive nanoparticles into polymer coating is presented as a solution to the reduced bioactivity and osteogenic activity of polymer coated 45S5 BGS. The Cu-BGN/gelatin nanocomposite coated BGS exhibiting high bioactivity, appropriate mechanical properties, and osteogenic potential are candidate biomaterials for bone tissue engineering/regeneration.