Flavylium dye as pH-tunable fluorescent and CD probe for double-stranded DNA and RNA

Ivo Crnolatac, Letícia Giestas, Gordan Horvat, António Jorge Parola, Ivo Piantanida

Research output: Contribution to journalArticlepeer-review

Abstract

The interaction of 4-(N,N-dimethylamino)-6-hydroxyflavylium cation with double stranded (ds-) DNA/RNA was studied by UV/Vis spectrophotometry, circular dichroism (CD), and also steady-state and time-resolved emission spectroscopies at neutral and weakly acidic conditions. At pH 5, the studied molecule, in its flavylium cationic form, showed considerable binding affinities (5 < logKs < 6) for all ds-DNA/RNA, contrary to chalcones forms (dominant at pH 7), which did not show binding to polynucleotides. Flavylium cation intercalated into ds-DNAs at variance to dominant groove aggregation within ds-RNA, which was reported by RNA-specific bisignate induced CD spectrum (ICD) bands. The intrinsically negligible fluorescence of flavylium was strongly increased upon the addition of DNA or RNA, whereby both the fluorescence intensity and emission lifetimes of complexes differed considerably: the strongest emission increase was observed for AU-RNA (detection limit estimated to 10 nM) followed by AT-DNAs and the much weaker effect of GC-DNAs. Both fluorescence sensitivity on the ds-DNA/RNA secondary structure and sequence-selective ICD bands make the flavylium–chalcones system an intriguing pH-switchable new probe for distinguishing between various polynucleotide sequences.

Original languageEnglish
Article number129
Pages (from-to)1-10
Number of pages10
JournalChemosensors
Volume8
Issue number4
DOIs
Publication statusPublished - 13 Dec 2020

Keywords

  • Chalcones
  • DNA/RNA binding
  • Flavylium cation
  • Fluorescence, circular dichroism
  • pH control

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