Electrochemical Insertion of Zinc Ions into Self-Organized Titanium Dioxide Nanotube Arrays to Achieve Strong Osseointegration with Titanium Implants

The construction of titanium dioxide (TiO2) nanotube arrays on the surface of metallic titanium has been demonstrated as a practical approach for improving the biocompatibility of titanium orthopedic implants. However, it remains a challenge to form strong bonds between such TiO2-based systems and the surrounding bone due to their lack of osseointegration ability. Herein, inspired by the intercalation mechanism of rechargeable batteries, a feasible electrochemical strategy is developed to insert high-concentration bioactive zinc ions into the lattices of TiO2 nanotube arrays with a controlled release performance and without nanostructure collapse. The zinc ion-inserted TiO2 nanotube arrays give titanium implants that exhibit excellent osteogenesis properties due to the synergistic effect of the nanotube topography and the release of zinc ions. Using the proposed electrochemical zinc insertion technique, the prepared substrates can trigger the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSCs) in vitro and subsequent implant-to-bone osseointegration in vivo. This study establishes a feasible and general electrochemical method to enhance the bioactivity and osseointegration of titanium implants, thereby providing a promising strategy for bone tissue repair.