Bioinspired Three-Dimensional Magnetoactive Scaffolds for Bone Tissue Engineering.

Bone tissue repair strategies are gaining increasing relevance due to the growing incidence of bone disorders worldwide. Biochemical stimulation is the most commonly used strategy for cell regeneration, while the application of physical cues, including magnetic, mechanical, or electrical fields, is a promising, however, scarcely investigated field. This work reports on novel magnetoactive three-dimensional (3D) porous scaffolds suitable for effective proliferation of osteoblasts in a biomimetic microenvironment. This physically active microenvironment is developed through the bone-mimicking structure of the scaffold combined with the physical stimuli provided by a magnetic custom-made bioreactor on a magnetoresponsive scaffold. Scaffolds are obtained through the development of nanocomposites comprised of a piezoelectric polymer, poly(vinylidene fluoride) (PVDF), and magnetostrictive particles of CoFe2O4, using a solvent casting method guided by the overlapping of nylon template structures with three different fiber diameter sizes (60, 80, and 120 μm), thus generating 3D scaffolds with different pore sizes. The magnetoactive composites show a structure very similar to trabecular bone with pore sizes that range from 5 to 20 μm, owing to the inherent process of crystallization of PVDF with the nanoparticles (NPs), interconnected with bigger pores, formed after removing the nylon templates. It is found that the materials crystallize in the electroactive β-phase of PVDF and promote the proliferation of preosteoblasts through the application of magnetic stimuli. This phenomenon is attributed to both local magnetomechanical and magnetoelectric response of the scaffolds, which induce a proper cellular mechano- and electro-transduction process.