* Corresponding authors

^a College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
E-mail: baolongniutyut@hotmail.com
Fax: +86-351-6111190
Tel: +86-351-6111197

^b Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024, P. R. China

^c Department of Biomedical Engineering, Research Center for Nano-biomaterials & Regenerative Medicine, College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China

^d Shanxi Key Laboratory of Material Strength & Structural Impact, Institute of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China