1. Materials and Process Simulation Center and ‡Department of Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
2. Department of Chemistry and Biochemistry and California NanoSystems Institute and ⊥Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
3. Department of Chemistry, and #Department of Materials Science, Chemistry, California Institute of Technology, Pasadena, California 91125, United States