ANNINE-6plus, a voltage-sensitive dye with good solubility, strong membrane binding and high sensitivity

Eur Biophys J. 2008 Apr;37(4):509-14. doi: 10.1007/s00249-007-0210-y. Epub 2007 Aug 9.


We present a novel voltage-sensitive hemicyanine dye ANNINE-6plus and describe its synthesis, its properties and its voltage-sensitivity in neurons. The dye ANNINE-6plus is a salt with a double positively charged chromophore and two bromide counterions. It is derived from the zwitterionic dye ANNINE-6. While ANNINE-6 is insoluble in water, ANNINE-6plus exhibits a high solubility of around 1 mM. Nonetheless, it displays a strong binding to lipid membranes. In contrast to ANNINE-6, the novel dye can be used to stain cells from aqueous solution without surfactants or organic solvents. In neuronal membranes, ANNINE-6plus exhibits the same molecular Stark effect as ANNINE-6. As a consequence, a high voltage-sensitivity is achieved with illumination and detection in the red end of the excitation and emission spectra, respectively. ANNINE-6plus will be particularly useful for sensitive optical recording of neuronal excitation when organic solvents and surfactants must be avoided as with intracellular or extracellular staining of brain tissue.

MeSH terms

  • Cell Line
  • Cell Membrane / chemistry*
  • Cell Membrane / metabolism*
  • Chrysenes / chemistry*
  • Coloring Agents / chemistry
  • Coloring Agents / pharmacology*
  • Humans
  • Lipid Bilayers / chemistry*
  • Models, Chemical
  • Neurons / metabolism*
  • Quaternary Ammonium Compounds / chemistry*
  • Salts / chemistry
  • Sensitivity and Specificity
  • Solubility
  • Spectrometry, Fluorescence / methods


  • ANNINE-6plus
  • Chrysenes
  • Coloring Agents
  • Lipid Bilayers
  • Quaternary Ammonium Compounds
  • Salts