CAREER: Voltage-sensitive Dyes based on Mesoscopic Electron Transfer

Indiana University, Bloomington IN

Investigators

Abstract

The research proposed herein is to create a new class of voltage sensitive dyes to measure cell membrane potentials and to track neuronal activity. Containing an electron donor-acceptor pair separated by a spacer, the dyes are based on the electric-field dependence of electron transfer, which competes with fluorescence emission and converts changes in electric fields to changes in fluorescence intensity. This type of dyes is unique in that their fluorescence intensity has wavelength-independent voltage response, and therefore all their emitted photons may be collected for voltage detection. This is in sharp contrast to existing voltage-sensitive dyes in which only a small portion of emitted photons are useful, and may therefore lead to photon counts hundreds of times larger and improve signal-to-noise ratio in measurements by more than one order of magnitude. Guided by both theoretical calculations and optical characterization, the aim is to synthesize dyes with sub-microsecond time response, high voltage sensitivity, and large fluorescence quantum yield, so that they can facilitate multi-site optical tracking of neuronal activity with sub-millisecond time resolution and sub-micrometer spatial resolution. Furthermore, based on this general voltage-sensing mechanism, more novel optical voltage probes can be developed, such as two-photon-absorbing voltage-sensitive fluorescent dyes that would allow for three-dimensional brain imaging and probes based on fluorescent proteins.