1. National Nanotechnology Laboratory (NNL) of CNR-INFM, Italian Institute of Technology (IIT) Lecce Unit, University of Salento, ISUFI Lecce, 73100 Italy, Institute for Micromanufacturing and Biomedical Engineering Program, Louisiana Tech University, 911 Hergot Avenue, Ruston, Louisiana 71272, and Applied Minerals, Inc., New York, New York