3D printed biomimetic nanocomposite scaffold with potential osteo-neurogenic differentiation of mesenchymal stem cells for bone repair

• Graphene oxide (GO) decorated with SPION (GO@SPION) was synthesized. • PCL scaffold with various ingredients were 3D printed using dual nozzle FDM method. • The middle section of PCL scaffold with high porosity was incorporated with bioactive naturally extracted HA, resembling cancellous section of the native bone. • The surrounding section of PCL scaffold with low porosity was filled with magneto-mechanical GO@SPION cue, resembling cortical section of the native bone. • This composite scaffold can promote osteogenesis and neurogenesis to repair bone defects. To mimic the natural bone tissue, integration of structure and function are the main concern for fabricating the tissue-engineering scaffold. Herein, a new 3D printed poly(ε-caprolactone) scaffold design was conducted with two distinct regions resembling the structure of cancellous and cortical sections of native bone with various amounts of porosity. Inspired by the native bone function, the middle section of the scaffold (i.e., the cancellous region) was incorporated with naturally extracted hydroxyapatite to promote bone remodeling processes. Besides, the circumferential section (i.e., cortical region) was filled with superparamagnetic iron oxide nanoparticles immobilized on graphene oxide (GO@SPION) to provide mechanical fidelity and also induce neurogenesis along with osteogenesis. The FESEM images of the composite scaffolds showed a uniform architecture in both regions, indicating the good printability of the materials. Young’s modulus and wettability of the scaffold were remarkably enhanced by incorporation of HA and GO@SPIONs to the scaffold. Osteo-differentiation was validated via upregulated expression of COL1, Runx2, OC and ON markers. This capability of the scaffold was also supported by the results of ALP activity, alizarin red staining and immunostaining assays. Moreover, Nestin, GFAP and MAP2 expression could be a sign of neurogenic differentiation capacity of the scaffold. Taken together, such scaffold would be a worthy asset for accelerating the bone rehabilitation through mimicking native complex bone tissue in the future studies.