title: Isomerically Pure Tetramethylrhodamine Voltage Reporters.
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.
authors.affiliation: Department of Chemistry, ‡Department of Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States.
authors.forename: Parker E
authors.initials: PE
authors.lastname: Deal
authors.affiliation: Department of Chemistry, ‡Department of Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States.
authors.forename: Rishikesh U
authors.initials: RU
authors.lastname: Kulkarni
authors.affiliation: Department of Chemistry, ‡Department of Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States.
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Al-Abdullatif
authors.affiliation: Department of Chemistry, ‡Department of Molecular & Cell Biology, and §Helen Wills Neuroscience Institute, University of California , Berkeley, California 94720, United States.
authors.forename: Evan W
authors.initials: EW
authors.lastname: Miller
mesh_terms: D004579:Electron Transport; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism*; D007536:Isomerism; D008564:Membrane Potentials; D055668:Photochemical Processes; D012235:Rhodamines / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines; C005358:tetramethylrhodamine