Hydrogel-based magnetoelectric microenvironments for tissue stimulation

The development of strategies to mimic the natural environment of tissues with engineered scaffolds remains one of the biggest challenges of tissue engineering. Hydrogels appear as suitable materials for this purpose due to their substantial water content, biocompatibility, and for being able to carry nanomaterials that introduce new functionalities to the hydrogel. The incorporation of magnetically responsive and, in particular, magnetoelectric materials into the hydrogel-based scaffolds are a promising approach for bone tissue engineering applications once it can promote not only tissue regeneration through magnetic to mechanic to electrical conversion/stimuli but also the external control of the scaffold by the application of magnetic fields. This work reports on a new CoFe₂O₄/ Methacrylated Gellan Gum (GGMA)/poly(vinylidene fluoride) (PVDF) hydrogel-based scaffold with 20 kPa Young's modulus and cell viability superior to 80%. The ≈ 1 μm thick PVDF/CoFe₂O₄ spheres added to GGMA gel (2 wt.%) exhibit 20 emu.g^-1 magnetization saturation, 2.7 kOe magnetic coercivity and β-phase contents ≈ 78%, leading to a piezoelectric response |d₃₃| of ≈ 22 pC N^-1 and a magnetoelectric response of Δ|d₃₃| ≈ 6 pC N^-1 at a DC magnetic field of 220 m T, as verified for the CoFe₂O₄/PVDF spheres with 20 wt.% filler content. Such characteristics allow novel tissue regeneration strategies approaches once CoFe₂O₄/GGMA/PVDF has a porous 3-D structure, biocompatibility, bioresorbability, and mechanical/electrical dynamic responses that can be triggered by an applied external magnetic field.