1. MEBCS Program, Singapore-MIT Alliance, National University of Singapore, 4 Engineering Drive 3, Singapore 117546, Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117546, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Yong Loo Lin School of Medicine, 8 Medical Drive, National University of Singapore, Singapore 117597