In situ evolution of bioactive copper phosphate nanoflowers on TiO2 nanotubes: An environment-responsive strategy for adaptive and persistent antibacterial interfaces

Abstract

Titanium dioxide nanotube (TNT) arrays have emerged as a premier scaffold for biomedical interfaces; however, their susceptibility to bacterial colonization remains a formidable challenge. Herein, we report an adaptive surface engineering strategy based on the phosphate-triggered, in situ structural evolution of copper-modified TNT arrays (TC) for infection control. While the electrodeposited metallic copper (Cu0) provides immediate and potent bactericidal efficacy against Enterococcus faecalis—a resilient periodontal pathogen—the surface undergoes a spontaneous chemical and morphological metamorphosis upon exposure to phosphate-rich physiological environments. This environment-driven transformation, mediated by the complexation of released Cu2+ ions and phosphate, culminates in the formation of hierarchical copper phosphate (Cu3(PO4)2·3H2O) nanoflower structures (TCN). Crucially, this self-stabilizing evolution not only preserves sustained antibacterial activity (ca. 90%) through a controlled ion-release mechanism but also dramatically enhances cytocompatibility, achieving over 80% viability in MC3T3-E1 pre-osteoblasts by mitigating the acute cytotoxicity of bare copper deposits. Systematic optimization reveals that a precise copper loading (∼55.6 μg cm−2, denoted as TC5) balances initial pathogen eradication with subsequent superhydrophilic surface stabilization. Our findings establish an autonomous, stimuli-responsive antibacterial platform that transitions from an aggressive bactericidal state to a stabilized, bio-instructive interface, offering a robust framework for the next generation of multifunctional dental and orthopedic implants. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.