1. Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio 43210, United States
2. Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
3. Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, United States
4. Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United States