1. Department of Chemical and Biomolecular Engineering University of Connecticut Storrs CT 06269 USA
2. Institute of Materials Science University of Connecticut Storrs CT 06269 USA
3. Laboratory of Theoretical and Computational Nanoscience National Center for Nanoscience and Technology Chinese Academy of Sciences Beijing 100190 China
4. Department of Chemistry University of Connecticut Storrs CT 06269 USA
5. Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 China
6. Department of Biomedical Engineering University of Connecticut Storrs CT 06269 USA