1. Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
2. Department of Advanced Nuclear Medicine Sciences National Institute of Quantum Sciences and Technologies Chiba 263‐8555 Japan
3. Institute of Traumatology and Orthopaedics Beijing Jishuitan Hospital Beijing Laboratory of Biomedical Materials Beijing 100035 P. R. China
4. Department of Vascular Surgery General Hospital of People's Liberation Army Beijing 100853 P. R. China