Facile Construction of Structural Gradient of TiO₂ Nanotube Arrays on Medical Titanium for High Throughput Evaluation of Biocompatibility and Antibacterial Property

Abstract

A structural gradient of TiO₂ nanotube arrays (TiO₂ NTAs) on medical titanium has been constructed by pull-stop-pull together with electrochemical anodization. The formation mechanism of TiO₂ NTAs with different nanostructures formed on a single titanium surface was discussed. It was found that the structural gradient of TiO₂ NTAs showed different properties in wettability translation, crystalline structure evolution, and electrodeposition of octacalcium phosphate (OCP). <i>In vitro</i> study demonstrated that the gradient TiO₂ NTAs also behaved significantly different in cell adhesion, extending and propagation of mouse MC3T3-E1, and formation of biofilm of <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and <i>Escherichia coli</i> (<i>E. coli</i>), respectively. It was found that the MC3T3-E1 cells were of higher bioactivity on the surface of 60 nm diameter TiO₂ NTAs, but <i>S. aureus</i> and <i>E. coli</i> preferred to TiO₂ NTAs with 90 nm diameter, which was attributable to the different adherent behaviors for cell and bacteria on nanosurfaces. Thus, the construction of structural gradient of TiO₂ NTAs can be an efficient technique for high throughput screening of their relationship of structure-properties on medical titanium surface.