Near-infrared voltage-sensitive fluorescent dyes optimized for optical mapping in blood-perfused myocardium.

Background: Styryl voltage-sensitive dyes (e.g., di-4-ANEPPS) have been used successfully for optical mapping in cardiac cells and tissues.

Nonlinear optical potentiometric dyes optimized for imaging with 1064-nm light.

Nonlinear optical phenomena, such as two-photon fluorescence (2PF) and second harmonic generation (SHG), in combination with voltage sensitive dyes, can be used to acquire high-resolution spatio temporal maps of electrical activity in excitable cells and tissue. Developments in 1064-nm fiber laser technology have simplified the generation of high-intensity, long-wavelength, femtosecond light pulses, capable of penetrating deep into tissue. To merge these two advances requires the design and synthesis of new dyes that are optimized for longer wavelengths and that produce fast and sensitive responses to membrane potential changes.

New near-infrared optical probes of cardiac electrical activity.

Styryl voltage-sensitive dyes (e.g., di-4-ANEPPS) have been widely and successfully used as probes for mapping membrane potential changes in cardiac cells and tissues.

Synthesis, spectra, delivery and potentiometric responses of new styryl dyes with extended spectral ranges.

Styryl dyes have been among the most widely used probes for mapping membrane potential changes in excitable cells. However, their utility has been somewhat limited because their excitation wavelengths have been restricted to the 450-550 nm range. Longer wavelength probes can minimize interference from endogenous chromophores and, because of decreased light scattering, improve recording from deep within tissue.

Sensitivity of second harmonic generation from styryl dyes to transmembrane potential.

In this article we present results from the simultaneous nonlinear (second harmonic generation and two-photon excitation fluorescence) imaging and voltage clamping of living cells. Specifically, we determine the sensitivity to transmembrane potential of second harmonic generation by ANEP-chromophore styryl dyes as a function of excitation wavelength and dye structure. We have measured second harmonic sensitivities of up to 43% per 100 mV, more than a factor of four better than the nominal voltage sensitivity of the dyes under "one-photon" fluorescence.