1. Key Laboratory of Bio-Resource and Eco-environment of Ministry of EducationCollege of Life SciencesSichuan University Chengdu Sichuan 610064 P. R. China
2. The Jack W. Szostak-CDHT Institute for Large Nucleic Acids Chengdu Sichuan 610041 P. R. China
3. SeNA Research Inc. Atlanta GA 30303 USA
4. SeNA Research InstituteDepartment of ChemistryGeorgia State University Atlanta GA 30303 USA