Nano-TiO₂/PEEK bioactive composite as a bone substitute material: in vitro and in vivo studies

Abstract

Background

Compared with titanium (Ti) and other metal implant materials, poly(ether-ether ketone) (PEEK) shows outstanding biomechanical properties. A number of studies have also reported attractive bioactivity for nano-TiO₂ (n-TiO₂).

Methods

In this study, n-TiO₂/PEEK nanocomposites were prepared, taking advantage of the unique properties of both PEEK polymer and n-TiO₂. The in vitro and in vivo bioactivity of these nanocomposites was assessed against a PEEK polymer control. The effect of surface morphology or roughness on the bioactivity of the n-TiO₂/PEEK nanocomposites was also studied. n-TiO₂/PEEK was successfully fabricated and cut into disks for physical and chemical characterization and in vitro studies, and prepared as cylindrical implants for in vivo studies. Their presence on the surface and dispersion in the composites was observed and analyzed by scanning and transmission electron microscopy and X-ray photoelectron spectroscopy.

Results

Bioactivity evaluation of the nanocomposites revealed that pseudopods of osteoblasts preferred to anchor at areas where n-TiO₂ was present on the surface. In a cell attachment test, smooth PEEK showed the lowest optical density value (0.56 ± 0.07) while rough n-TiO₂/PEEK exhibited the highest optical density value (1.21 ± 0.34, P < 0.05). In in vivo studies, the percent bone volume value of n-TiO₂/PEEK was approximately twice as large as that of PEEK (P < 0.05). Vivid three-dimensional and histologic images of the newly generated bone on the implants further supported our test results.

Conclusion

Our study demonstrates that n-TiO₂ significantly improves the bioactivity of PEEK, especially if it has a rough composite surface. A n-TiO₂/PEEK composite with a rough surface could be a novel alternative implant material for orthopedic and dental applications.

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Keywords:

• polyether-ether-ketone
• bioactivity
• TiO₂
• nanocomposite
• polymer
• implant

Acknowledgments

This work was supported by the State Key Development Program for Basic Research of China (grant 2007CB936103), the Fundamental Research Funds for the Central Universities and Peking University 985 Grant, Nanospecial Program of Science and Technology Development of Shanghai (1052nm06600), and Key Medical Program of Science and Technology Development of Shanghai (09411954900). The authors express appreciation to Dr Dongsheng Wang (Institute of Stomatology, Chinese PLA General Hospital) for his technical assistance in histologic analysis. The authors also thank Xiaohong Wu for assistance in microcomputed tomography analysis, Feilong Nie for assistance with the animal experiments, and Qiuhong Li for assistance with the cell experiments.

Disclosure

The authors report no conflicts of interest in this work.