[1] Natl Univ Singapore, Dept Chem & Biomol Engn, Singapore 117576, Singapore
[2] Natl Univ Singapore, Environm Res Inst, Singapore 117411, Singapore
[3] Hong Kong Univ Sci & Technol, Div Biomed Engn, Dept Chem, Kowloon, Hong Kong, Peoples R China
[4] S China Univ Technol, State Key Lab Luminescent Mat & Devices, Guangdong Innovat Res Team, SCUT HKUST Joint Res Lab, Guangzhou 510640, Guangdong, Peoples R China
[5] Inst Mat Res & Engn, Singapore 117602, Singapore