1. a The Helen I. Moorehead-Laurencin Biomaterials Research Laboratory, Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
2. b The Helen I. Moorehead-Laurencin Biomaterials Research Laboratory, Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, Department of Orthopaedic Surgery, The Medical College of Pennsylvania and Hahnemann University, Philadelphia, Pennsylvania, USA
3. c The Helen I. Moorehead-Laurencin Biomaterials Research Laboratory, Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, Department of Orthopaedic Surgery, The Medical College of Pennsylvania and Hahnemann University, Philadelphia, Pennsylvania, USA, Department of Chemical Engineering, Drexel University, Philadelphia, Pennsylvania, USA