A Dimethylaminophenyl-Substituted Naphtho[1,2-b]quinolizinium as a Multicolor NIR Probe for the Fluorimetric Detection of Intracellular Nucleic Acids and Proteins

AbstractThe dye 3‐(4‐(N,N‐dimethylamino)phenyl)naphtho[1,2‐b]quinolizinium was synthesized by means of a Suzuki–Miyaura reaction in good yield, and its binding properties with duplex DNA, quadruplex DNA (G4‐DNA), RNA, and bovine serum albumin (BSA) were investigated by photometric, fluorimetric and polarimetric titrations and DNA denaturation analysis. The compound intercalates into DNA and RNA, associates in binding site I of BSA, and binds to G4‐DNA by terminal π stacking. The ligand exhibits a fluorescence light‐up effect upon complexation to these biomacromolecules, which is more pronounced and blue shifted in the presence of BSA (Φfl=0.29, λfl=627 nm) than with the nucleic acids (Φfl=0.01–0.05, λfl=725–750 nm). Furthermore, the triple‐exponential fluorescence decay of the probe when bound to biomacromolecules in a cell enables their visualization in this medium and the differential labeling of cellular components

Berberrubine Phosphate: A Selective Fluorescent Probe for Quadruplex DNA

A phosphate-substituted, zwitterionic berberine derivative was synthesized and its binding properties with duplex DNA and G4-DNA were studied using photometric, fluorimetric and polarimetric titrations and thermal DNA denaturation experiments. The ligand binds with high affinity toward both DNA forms (Kb = 2–7 × 105 M−1) and induces a slight stabilization of G4-DNA toward thermally induced unfolding, mostly pronounced for the telomeric quadruplex 22AG. The ligand likely binds by aggregation and intercalation with ct DNA and by terminal stacking with G4-DNA. Thus, this compound represents one of the rare examples of phosphate-substituted DNA binders. In an aqueous solution, the title compound has a very weak fluorescence intensity (Φfl < 0.01) that increases significantly upon binding to G4-DNA (Φfl = 0.01). In contrast, the association with duplex DNA was not accompanied by such a strong fluorescence light-up effect (Φfl < 0.01). These different fluorimetric responses upon binding to particular DNA forms are proposed to be caused by the different binding modes and may be used for the selective fluorimetric detection of G4-DNA