Synthesis and biological properties of Zn-incorporated micro/nano-textured surface on Ti by high current anodization

Abstract

It is acknowledged that ideal implant coatings should possess micro/nano-textured surface, have good interfacial bonding, and can release bioactive elements. In this study, we fabricated a Zn-incorporated micro/nano-textured surface by one-step high current anodization (HCA) in an aqueous solution with 10g/L of NaOH and different concentrations of Zn(NO3)2 (4, 7, and 12g/L). The control group of Zn-free was fabricated in the electrolyte of 7g/L Zn(NO3)2. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and inductively coupled plasma mass spectroscopy (ICP-MS) were used to analyze the morphology, composition, microstructure, and Zn+ release kinetics of the micro/nano-textured coatings. The biological properties of the surface structure were evaluated by cytotoxicity assay, cell viability, cytoskeletal assembly and alkaline phosphatase activity. Our results show the micro/nano-textured surface is composed of TiO2 mesoporous arrays, into which the Zn is demonstrated to be incorporated in the form of ZnO. The Zn content in the surface and release level of Zn2+ can be tailored through varying Zn(NO3)2 concentration in the electrolyte. In addition, the surface oxide layers show good interfacial bonding strength to the substrate. Compared with pure Ti and anodized Zn-free samples, the Zn-incorporated surface can upregulate osteoblast functions such as proliferation and alkaline phosphatase activity, which are assayed by MTT and ALP staining experiments, respectively. Collectively, this micro/nano-textured structure combined with high interfacial bonding strength and release of Zn2+ render the material surface promising as orthopedic implant coatings.