1. Department of Polymer Science, The University of Akron, Akron, Ohio 44325, United States
2. Department of Pharmaceutical Sciences, Merck & Co., Inc., 90 E. Scott Ave., Rahway, New Jersey 07065, United States
3. Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
4. Department of Mechanical Engineering and Material Science, Duke University, Durham, North Carolina 27708, United States
5. Orthopaedic Surgery, Duke University, Durham, North Carolina 27708, United States