1. School
of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457
2. Nanyang
Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, Singapore 637141
3. Bioengineering
and Materials Science and Engineering Departments, University of California, Berkeley, California 94720-1760, United States