1. School
of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao, China 266042
2. Department
of Medicinal Chemistry, Amgen Inc., One Amgen Center Drive, Thousand Oaks, California 91320-1799, United States
3. Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States