Isomerically Pure Tetramethylrhodamine Voltage Reporters

J Am Chem Soc. 2016 Jul 27;138(29):9085-8. doi: 10.1021/jacs.6b05672. Epub 2016 Jul 18.

Abstract

We present the design, synthesis, and application of a new family of fluorescent voltage indicators based on isomerically pure tetramethylrhodamines. These new Rhodamine Voltage Reporters, or RhoVRs, use photoinduced electron transfer (PeT) as a trigger for voltage sensing, display excitation and emission profiles in the green to orange region of the visible spectrum, demonstrate high sensitivity to membrane potential changes (up to 47% ΔF/F per 100 mV), and employ a tertiary amide derived from sarcosine, which aids in membrane localization and simultaneously simplifies the synthetic route to the voltage sensors. The most sensitive of the RhoVR dyes, RhoVR 1, features a methoxy-substituted diethylaniline donor and phenylenevinylene molecular wire at the 5'-position of the rhodamine aryl ring, exhibits the highest voltage sensitivity to date for red-shifted PeT-based voltage sensors, and is compatible with simultaneous imaging alongside green fluorescent protein-based indicators. The discoveries that sarcosine-based tertiary amides in the context of molecular-wire voltage indicators prevent dye internalization and 5'-substituted voltage indicators exhibit improved voltage sensitivity should be broadly applicable to other types of PeT-based voltage-sensitive fluorophores.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electron Transport
  • Fluorescent Dyes / chemistry*
  • Fluorescent Dyes / metabolism*
  • Isomerism
  • Membrane Potentials*
  • Photochemical Processes
  • Rhodamines / chemistry*
  • Rhodamines / metabolism*

Substances

  • Fluorescent Dyes
  • Rhodamines
  • tetramethylrhodamine