1. Department of Chemical Science and Technology , Kunming University , Yunnan, Kunming 65200, P.R. China
2. Medical School, Kunming University , Yunnan, Kunming 65200, P.R. China, Fax: +86-871-65098476
3. Key Laboratory of Yunnan Provincial Higher Education Institutions for Organic Optoelectronic Materials and Devices , Kunming University , Yunnan, Kunming 65200, P.R. China
4. School of International Cultures and Education, Yunnan University of Finance and Economics , Yunnan, Kunming 650221, P.R. China
5. Medical School, Kunming University , Yunnan, Kunming 65200, P.R. China