Unveiling the Role of Zinc on the Nanotitania Network in Determining the <i>In Vitro</i> and <i>In Vivo</i> Characteristics of Titanium-Based Orthopedic Implants

This study focuses on the development of a Zn-incorporated biomimetic nanotitania network layer on Ti metal, formulated to replicate the microporous structure of natural bone. Varying concentrations of Zn were subjected to surface property evaluation concerning phase, hydrophilicity, and surface roughness for an optimal surface interface in <i>in vitro</i> and <i>in vivo</i> studies. The alkali treatment has created an improved roughness profile and water contact angle over the surface-modified samples, which strengthens the implant interface, ensuring long-term stability and improved bone integration. The incorporation of Zn onto the nanotitania layer and its subsequent heat treatment at 600 °C have supported the formation of ZnO along with a dominant anatase TiO₂ over the modified surface, contributing to the antibacterial activity against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. The cytocompatibility of MG63 cells toward varying concentrations of Zn was evaluated for <i>in vitro</i> characteristics by assessing cytoskeletal attachment, mitochondrial potential, live-dead evaluation, extracellular matrix mineralization, and ALP activity. Further, utilizing the additive manufacturing technology, porous Ti scaffolds were fabricated and subsequently surface functionalized with an optimized concentration of Zn for <i>in vivo</i> studies in a rat (<i>Rattus norvegicus</i>) model to evaluate the bone-implant integration. The rat bone defect model examined by X-ray imaging, micro-CT, and osteogenic gene expression profile was suggestive of superior osseointegration properties of our optimal Zn concentration in comparison with the bare Ti scaffold. Hence, this Zn-incorporated biomimetic titania nanonetwork layer is expected to maintain a delicate balance to promote bone healing and avoid toxic effects in clinical trials.