In situ synthesis of iron oxide on graphene oxide: Assisting bone scaffold to achieve magnetoelectrical stimulation

Abstract

Integration of superparamagnetic iron oxide (Fe₃O₄) nanoparticles and piezoelectric polyvinylidene fluoride (PVDF) was expected to reconstruct the magnetoelectric microenvironment of bone tissue. Nevertheless, the dispersion of Fe₃O₄ in PVDF matrix was a challenge. Herein, Fe₃O₄ nanoparticles were in situ grown on the surface of graphene oxide (GO) nanosheets (GO@Fe₃O₄) to inhibit their aggregation in PVDF scaffold. Specifically, the enormous specific surface area of GO supplied abundant space for the uniform nucleation and growth of Fe₃O₄ nanoparticles. In turn, Fe₃O₄ would act as steric hindrance to suppress the stacking of GO nanosheets. Morphological analysis indicated that GO@Fe₃O₄ was uniformly distributed in PVDF matrix. Particularly, X-ray photoelectron spectroscopy and polarization microscope measurements revealed that oxygen-containing functional groups on GO forced the orientation arrangement of -CF₂ groups in PVDF through hydrogen bonding, forming piezoelectric β phase. As a result, the electrical output of the scaffold was significantly enhanced, with an output current of 57 nA and voltage of 8.5 V. Cell culture demonstrated that the enhanced electrical stimulation and synergistic magnetic stimulation effectively promoted the proliferation and differentiation of cells. Overall, this work might provide a perspective for the construction of scaffolds with simultaneous electrical and magnetic stimulation.