1. Graduate Nanotechnology Program, School of Sciences & Engineering, The American University in Cairo, 11835 New Cairo, Egypt
2. Department of Chemistry, School of Sciences & Engineering, The American University in Cairo, AUC Avenue, P. O. Box 74, New Cairo 11835, Egypt
3. Department of Nanobiophotonics, Leibniz Institute for Photonic Technology, Albert Einstein Str. 9, Jena 07745, Germany