1. Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States
2. Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
3. Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States