Binary Doping of Strontium and Copper Enhancing Osteogenesis and Angiogenesis of Bioactive Glass Nanofibers while Suppressing Osteoclast Activity

Electrospun bioactive glass fibers show great potential as scaffolds for bone tissue engineering due to their architectural biomimicry of the bone extracellular matrix and their composition capable of providing soluble bioactive cues for bone regeneration and remodeling. Trace elements can be doped to further promote osteogenesis and angiogenesis during bone regeneration. Cationic substitution of strontium for calcium in bioactive glass positively enhances osteoblast phenotype, while suppressing osteoclast activity. Further, the addition of copper spontaneously improves the vascularization during neobone formation. The objective of this study was to fabricate and characterize electrospun bioactive glass fibers doped with strontium and copper and evaluate their potential for bone repair/regeneration in vitro. Different ratios of strontium and copper were doped in electrospun bioactive glass fibers. The released strontium and copper from doped fibers could reach effective concentrations within 40 h and last for 4 weeks. These bioactive glass fibers demonstrate their bioactivity by promoting osteoblastic and endothelial cell activity and inhibiting the formation of osteoclasts or bone resorbing cells. Additionally, in vitro cell culture of different cell types in the presence of extraction solutions of the electrospun bioactive glass fibers showed that the dopants achieved their individual goals without causing significant cytotoxicity. Altogether, this novel class of bioactive glass fibers holds great promise for bone regeneration.