1. Bio/Nano Technology Group, Institute for Nanoscience & Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
2. Materials Science & Engineering Program, University of Arkansas, Fayetteville, Arkansas 72701, United States
3. Department of Biological & Agricultural Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
4. Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States