Solvent-assisted optical modulation of FRET-induced fluorescence for efficient conjugated polymer-based DNA detection

Mijeong Kang, Okhil Kumar Nag, Sungu Hwang, Inhong Kim, Haesik Yang, Kwangseuk Kyhm, Han Young Woo

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16 Citations (Scopus)

Abstract

The solvent effects were studied in fluorescence resonance energy transfer (FRET) from a cationic polyfluorene copolymer (FHQ, FPQ) to a fluorescein (Fl)-labelled oligonucleotide (ssDNA-Fl). Upon addition of dimethyl sulfoxide (DMSO), the optical properties of polymers and the probe dye were substantially modified and the FRET-induced PL signal was enhanced 3.8-37 times, relative to that in phosphate buffer solution (PBS). The hydrophobic interaction between polymers and ssDNA-Fl is expected to decrease in the presence of DMSO, which induces the weaker polymer/ssDNA-Fl complexation with longer intermolecular donor-acceptor separation and perturbs the competition between the FRET and PL quenching processes such as photo-induced charge transfer. The gradual decrease in Fl PL quenching with increasing the DMSO content was investigated by measuring the Stern-Volmer quenching constants (3.3-4.2 × 10 6 M -1 in PBS, 0.56-1.1 × 10 6 M -1 in 80 vol% DMSO) and PL lifetime of the excited Fl* in polymer/ssDNA-Fl (600 ps in PBS and 2120 ps in 80 vol% DMSO for FHQ/ssDNA-Fl) in PBS/DMSO mixtures. The substantially reduced PL quenching would amplify the resulting FRET Fl signal. The signal amplification in real DNA detection was also demonstrated with fluorescein-labelled PNA (probe PNA) in the presence of a complementary target DNA and noncomplementary DNA in aqueous DMSO solutions. This approach suggests a simple way of modifying the fine-structure of polymer/ssDNA-Fl and improving the detection sensitivity in conjugated polymer-based FRET bioassays.

Original languageEnglish
Pages (from-to)15482-15489
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume12
Issue number47
DOIs
Publication statusPublished - 2010 Dec 21
Externally publishedYes

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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