1. Key Laboratory of Drug-Targeting and Drug-Delivery Systems of the Ministry of Education, Department of Medicinal Chemistry,West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041, P. R. China, and Department of Nuclear Medicine Affiliated Hospital, Luzhou Medical College, No. 25 Taiping Street, Luzhou, Sichuan, 646000, P. R. China