1. Nanotechnology Center, University of Arkansas at Little Rock, Little Rock, Arkansas 72204, Department of Chemistry, University of Arkansas at Little Rock, Little Rock, Arkansas 72204, Physics Department, University of Arkansas, Fayetteville, Arkansas 72701, National Institute for Research and Development of Isotopic and Molecular Technologies, P.O. Box 700, R-400293 Cluj-Napoca, Romania, and Duke Human Vaccine Institute, Duke University, Durham, North Carolina 27710