Effect of titanium-based anisotropic magnetic hydrogel coating on osseointegration

Titanium (Ti) implants suffer from elastic modulus mismatch with bone tissue, causing stress-shielding effects that lead to osteopenia and aseptic loosening. While hydrogel coatings have been explored to improve osseointegration, conventional hydrogels are limited by their isotropic structure and poor mechanical performance. Herein, we developed an anisotropic magnetic hydrogel coating on polydopamine-modified Ti surfaces by incorporating polydopamine-functionalized magnetic nanoparticles and calcium phosphate oligomers into gelatin methacryloyl matrices. The coating exhibited combined advantages of structural anisotropy, magnetic responsiveness and high mechanical strength, which facilitated BMSC adhesion and aligned orientation. Upon exposure to an external dynamic magnetic field, the stiffness of the hydrogel coating can be reversibly tuned. Both in vitro and in vivo results demonstrated that the anisotropic magnetic hydrogel coating significantly enhanced BMSC osteogenic differentiation and Ti implant osseointegration under dynamic mechanical stimulation. This study provides a new approach for designing smart orthopedic implants and establishes a basis for magnetically driven remote dynamic therapy.