1. School of Chemical and Biomedical Engineering 70 Nanyang Drive Singapore 637457 Singapore
2. National Engineering Research Centre for Nanomedicine College of Life Science and Technology Huazhong University of Science and Technology Wuhan 430074 P. R. China
3. School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
4. Lee Kong Chian School of Medicine Nanyang Technological University Singapore 636921 Singapore