Fluorescent sensors from branched diphenylacetylenes

Abstract

Five new fluorophores containing phenylene-ethynylene branches with salicylic acid (F2-F5) and trimethylammonium (4N⁺Cl⁻) termini were synthesized and evaluated as chemical and biological sensors. The tribranched fluorophore (F4) with salicylic acid termini exhibited the highest Cu²⁺ quenching sensitivity in aqueous solution; K[subscript sv] = 5.79 × 10⁶ M⁻¹. The paper-based sensor fabricated from this compound allows picomole detection of Cu²⁺ by naked eye. The tetrabranched fluorophore (4N⁺Cl⁻) with trimethylammonium termini can bind with DNA in aqueous buffered solution pH 7.4. Upon DNA binding, the fluorescent signal of the fluorophore increases presumably due to the reduction of geometrical relaxation and collisional self-quenching processes. The interaction between the fluorophore and DNA were useful for FRET detection of DNA sequences via DNA/DNA hybridization in the presence of SyBrGreen commercial fluorescence dye.