1. School of Materials Science and Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore
2. Department of Environmental Health Harvard T. H. Chan School of Public Health 665 Huntington Avenue Boston MA 02115 USA
3. Environmental Chemistry and Materials Centre, Nanyang Environment and Water Research Institute (NEWRI) Nanyang Technological University 1 Cleantech Loop, CleanTech One Singapore 637141 Singapore
4. Skin Research Institute of Singapore Biomedical Science Institutes Immunos, 8A Biomedical Grove Singapore 138648 Singapore