A confining mesh enables concurrent calcium phosphate deposition and preservation of TiO2 nanotube topography for synergistic osteogenic regulation

• A preserving mesh maintaining titanium dioxide nanotubes during calcium phosphorus deposition to accelerate osseointegration. • A new practical methodology for concurrent surface functionalization with underlying nanostructure preservation. • Critical evidence for the necessity of topographical preservation when coating deposition. Bioactive coating would compromise the pre-engineered surface topography of custom-made titanium bone substitutes, diminishing their therapeutic synergy. Although titanium dioxide nanotubes (TNTs) serve as well-established platforms for molecular loading, post-deposition structural alterations frequently occur, compromising their functionality. Thus, we proposed a topography-preserving mesh strategy to maintain TNTs during coating processes. This ultrathin mesh adheres robustly to TNTs, enabling site-specific localized coatings. Using an integrated anodization-sonication protocol, we successfully fabricated the mesh and achieved spatially confined calcium phosphate (CaP) deposition while preserving TNTs, verified by scanning electron microscopy. Comparative evaluations were conducted: in vitro with preosteoblasts (MC3T3-E1) and macrophages (RAW 264.7), and in vivo using beagle mandibular implantation models, comparing CaP/Mesh/TNTs versus CaP/TNTs with compromised nanotopography. The CaP/Mesh/TNTs construct significantly enhanced MC3T3-E1 cell adhesion, proliferation, and osteogenic differentiation. Simultaneously, it induced pro-healing morphological adaptations in RAW 264.7 cells, promoting M2 polarization with upregulation of VEGF and PDGF-BB secretion. Furthermore, macrophage-conditioned medium from the CaP/Mesh/TNTs most potently enhanced MC3T3-E1 osteogenesis. In vivo validation confirmed accelerated early-phase osseointegration with CaP/Mesh/TNTs. This study demonstrates that loading approaches on nanostructured surfaces must address topographical degradation and provides a practical methodology for concurrent surface functionalization with preserved nanotopography.