Measuring DNA Charge Transport on a Surface Using a Redox Modulated Fluorescence Intensity Strategy with DNA SAMs

The double stranded DNA helix has drawn great attention across different research areas. Various types of platforms have been used to study DNA charge transfer (CT) system. Two types of DNA CT platforms are considered as the most effective: the photoinduced CT in solution with assembled donor and acceptor and electrochemistry on ground state CT in a DNA self-assembled monolayer (SAM)1. We will show a new approach for the study of DNA CT on gold surface by studying the redox modulated fluorescence signal of a co-deposited double-stranded DNA assemblies labeled with Methylene Blue (MB) or AlexaFluoro488 (AF488). We demonstrate a method that can optically distinguish between the two mechanisms of the MB redox on DNA-modified surface: namely either DNA CT mediated reduction or the direct reduction of MB by the gold surface2. Given the fact that the studies on DNA-mediated electrochemistry on surface has been mainly using electrochemical measurements and we still do not fully understand the full picture of the DNA CT, we believe that this study will provide a fresh opinion and facilitate understanding on the DNA CT mechanism on electrode surface. Reference: Arnold, A. R.; Grodick, M. A.; Barton, J. K. DNA Charge Transport: From Chemical Principles to the Cell. Cell Chem. Biol. 2016, 23 (1), 183–197. Pheeney, C. G.; Barton, J. K. DNA Electrochemistry with Tethered Methylene Blue. Langmuir 2012, 28 (17), 7063–7070. Muren, N. B.; Olmon, E. D.; Barton, J. K. Solution, Surface, and Single Molecule Platforms for the Study of DNA-Mediated Charge Transport. Chem. Chem. Phys. 2012, 14 (40), 13754–13771.