Regulation of TiO2 @PVDF piezoelectric nanofiber membranes on osteogenic differentiation of mesenchymal stem cells

Bioactive piezoelectric materials with similar properties as natural bone tissue with piezoelectricity have been explored for bone repair. Polyvinylidene fluoride (PVDF) is among the most studied piezoelectric polymers and has been manifested to promote osteogenic differentiation. Unfortunately, in the practical application of bone repair, bioactive materials as implants have faced poor electrical signal stability and poor modulation of bone regeneration, which have seriously hindered their further development. Here, we fabricated a composite piezoelectric fibrous membrane with titanium dioxide (TiO2) nanoparticles and PVDF (TiO2 @PVDF) for cellular osteogenic differentiation. The expression quantity of the gene osteocalcin (OCN) with the piezoelectric fibrous membrane was 49 times and 6 times higher than the expression quantity of OCN with the control group and with the pure polyvinylidene fluoride (PVDF), respectively. Moreover, the membrane with 0.3 wt% TiO2 (P-0.3TN) generated high surface potential and significantly promoted cell adhesion and proliferation through electromechanical stimulation early in osteogenic differentiation. Alkaline phosphatase (ALP) activity was increased up to 2-fold by stimulation of electrical and mechanical signals through piezoelectric fibers, effectively inducing osteogenic differentiation at the early stage. The proposed mechanism of regulating osteogenic differentiation behavior by the surface potential of TiO2 @PVDF piezoelectric fiber composite membrane provides guidance for designing electroactive materials to promote osteogenic differentiation and bone regeneration and remodeling.