Title
G-quadruplex fluorescence sensing by core-extended naphthalene diimides
Author
Michela Zuffo, Filippo Doria, Silvia Botti, Greta Bergamaschi, Mauro Freccero
Year
2016
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
Abstract
Fluorescent sensing of G-quadruplex nucleic acids (G4s) is an effective strategy to elucidate their role in vitro and in vivo. Small molecule ligands have often been exploited, producing an emission light up upon binding. Naphthalene diimides (NDIs), although potent G4 binders exhibiting red-NIR fluorophores, have only been marginally exploited, as they are usually quenched upon binding. Contrary, aggregating core-extended naphthalene diimides (cex-NDIs) proved to be effective probes. We prepared a library of eighteen cex-NDIs by organic synthesis, characterising their aggregation-dependent absorption and emission properties. Absorption and emission titrations, fluorescent intercalator displacement assay (FID) and circular dichroism (CD) analysis were performed to elucidate their behavior as G4 fluorescent sensors, selectivity and binding mode. cex-NDIs aggregate under aqueous solvents and as a result, their fluorescence is mostly quenched under physiological conditions. Upon G4 binding, they disaggregate into binding monomers, producing a fluorescent light-up with anti-parallel and hybrid G4s. Contrary, with parallel G4s a light-off was recorded. For the formers a groove-like interaction was inferred by ICD signals, while for the latter an end-stacking interaction mode was hypothesized by G4-FID data. cex-NDIs G4 sensing mechanism works via a induced disaggregation. The emission response depends on the G4 topology, which dictates the prevailing -groove or end-stacking- binding mode.
Instrument
J-710
Keywords
Circular dichroism, Induced CD, DNA structure, Ligand binding, Biochemistry, Materials