1. Département de Chimie Moléculaire UMR-5250, ICMG FR-2607, CNRS Université Joseph Fourier, BP-53, 38041 Grenoble Cedex 9, France, Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, Israel, and cThe National Institute for Biotechnology in the Negev, and the Ilse Katz Center for Meso- and Nano-scale Science and Technology, P.O. Box 653, 84105 Beer-Sheva, Israel