Antibacterial and Osteogenic Properties of 3D-Printed Poly(ε-Caprolactone) PCL/Bioactive Glass Scaffolds

Bioactive glasses (BGs) have been thoroughly investigated for their osteogenic and antibacterial potential, which may be modulated through their composition. In this study, two different poly(ε-caprolactone) (PCL)/BG composites, SBA3 and SBA3_Cu, were fabricated using fused deposition modeling to obtain planar samples for antibacterial assays and scaffolds with a bone-like tridimensional architecture, while neat PCL constructs were kept as controls. Escherichia coli was selected as prototypical Gram-negative model for investigating implant-associated bone infections. The scaffolds were seeded with adipose derived stem cells (ASCs), a model of osteoblastic precursors, to evaluate their osteogenic properties. Both the composites containing SBA3 and SBA3_Cu relevantly reduced the bacterial metabolic activity and viability after 5 h, while the gene expression analysis of RUNX2, OSX and ALP did not reveal any significant difference among the tested biomaterials. MicroCT analysis demonstrated consistent mineral matrix formation in osteogenic medium, with the exception of PCL/SBA3_Cu. These findings suggest that copper addition could not produce any beneficial osteogenic or antibacterial effect, within the experimental setting adopted. Hence, optimizing the elemental composition and dissolution kinetics of copper-doped BGs is mandatory to provide appropriate differentiative cues to mesenchymal stromal cells, maintaining, at the same time, the antibacterial features required for bone alloplastic materials.