1. Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK
2. Faculty of Engineering, Electrical Engineering, Integrated Lightwave Research Group, University of Malaya, Kuala Lumpur 50603, Malaysia
3. Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 65 Landsdowne Street, Cambridge, MA 02139, USA
4. Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
5. Center of Excellence in Nanotechnology, King Fahd University of Petroleum & Minerals, Dhahran 34464, Saudi Arabia