[1] ASTAR, Inst Bioengn & Nanotechnol, Singapore 138669, Singapore
[2] Natl Univ Singapore, Dept Chem, Fac Sci, Singapore 117543, Singapore
[3] NUS Grad Sch Integrat Sci & Engn, Singapore 117456, Singapore
[4] NUS, Mechanobiol Inst, Singapore 117411, Singapore
[5] NUS, Dept Physiol, Singapore 117597, Singapore
[6] Singapore MIT Alliance Res & Technol, Singapore 117543, Singapore
[7] Singapore MIT Alliance, CSB Program, Singapore 117576, Singapore
[8] NUS, NUS Tissue Engn Programme, DSO Labs, Singapore 117597, Singapore
[9] MIT, Dept Mech Engn, Cambridge, MA 02139 USA