Cationic Conjugated Polyelectrolytes with Molecular Spacers for Efficient Fluorescence Energy Transfer to Dye-Labeled DNA

Authors

  • H. Y. Woo,

    1. Departments of Chemistry and Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA
    2. Department of Nanomaterials Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan, 609-735, Korea
    Search for more papers by this author
  • D. Vak,

    1. Departments of Chemistry and Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA
    2. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju, 500-712, Korea
    Search for more papers by this author
  • D. Korystov,

    1. Departments of Chemistry and Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA
    Search for more papers by this author
  • A. Mikhailovsky,

    1. Departments of Chemistry and Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA
    Search for more papers by this author
  • G. C. Bazan,

    1. Departments of Chemistry and Materials, Institute for Polymers and Organic Solids, University of California, Santa Barbara, CA 93106, USA
    Search for more papers by this author
  • D.-Y. Kim

    1. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju, 500-712, Korea
    Search for more papers by this author

  • The authors are grateful to the National Science Foundation, the Office of Naval Research and the National Laboratory program of KOSEF and BK21 program for financial support.

Abstract

Two water-soluble conjugated polyelectrolytes, poly(9,9′-bis(6-N,N,N-trimethylammoniumhexyl)fluorene-alt-1,4-(2,5-bis(6-N,N,N-trimethylammoniumhexyloxy))phenylene) tetrabromide (P1i) and poly((10,10′-bis(6-N,N,N-trimethylammoniumhexyl)-10H-spiro(anthracene-9,9′-fluorene))-alt-1,4-(2,5-bis(6-N,N,N-trimethylammoniumhexyloxy))phenylene) tetrabromide (P2i) are synthesized, characterized, and used in fluorescence resonance energy transfer (FRET) experiments with fluorescein-labeled single-stranded DNA (ssDNA-Fl). P1i and P2i have nearly identical π-conjugated backbones, as determined by cyclic voltammetry and UV-vis spectroscopy. The main structural difference is the presence of an anthracenyl substituent, orthogonal to the main chain in each of the P2i repeat units, which increases the average interchain separation in aggregated phases. It is possible to observe emission from ssDNA-Fl via FRET upon excitation of P2i. Fluorescein is not emissive within the ssDNA-Fl/P1i electrostatic complex, suggesting Fl emission quenching through photoinduced charge transfer (PCT). We propose that the presence of the anthracenyl “molecular bumper” in P2i increases the distance between optical partners, which decreases PCT more acutely relative to FRET.

Ancillary