1. College of Biotechnology and Pharmaceutical Engineering Nanjing Tech University 30 Puzhu Rd S Nanjing 211816 P. R. China
2. Institute of Chemistry & Biomedical Science Nanjing University No.163, Xianlin Avenue, Qixia District Nanjing 210093 P. R. China
3. Department of Chemistry and Biochemistry Texas Tech University Lubbock TX 79409-1061 USA