The development of diverse organic fluorophores in the visible (400-700 nm) and NIR (700-1000 nm) regions of the electromagnetic spectrum has enabled multiplexed experiments to study live cells and simple organisms with high resolution. Multicolor imaging in more complex systems such as mammals is limited in signal and resolution by diffuse light originating from background and scattering at visible and near-infrared (NIR) wavelengths. By moving to detection in the shortwave infrared region (1000-2000 nm), increased contrast and resolution can be obtained with non-invasive methods at video-rate speeds. While the optical properties of tissue are ideal for SWIR imaging, non-toxic organic small molecules with bright emission &gt; 1000 nm are necessary to obtain high signal with minimal biological perturbation. Polymethine dyes are a prime scaffold for creating SWIR probes, as they can be red-shifted with predictable structural changes. We hypothesized that a flavylium heterocycle, containing no heavy atoms and with an electron donating group, would impart red-shifted photophysical properties without diminished Φ<sub>F</sub>. With absorbance and emission in the SWIR, the 7-dimethylamino flavylium heptamethine dye is approximately 200 nm red-shifted from heptamethine cyanine dyes traditionally employed for optical imaging at NIR wavelengths. Systematic changes to the flavylium scaffold reveal insight into relationships between structure and photophysical properties. Dyes with further bathochromic shifts to absorption and emission improve the spatiotemporal resolution in non-invasive multicolor imaging in mice.

Flavylium polymethine fluorophores for multiplexed <i>in vivo</i> imaging with shortwave infrared light

2019 Fall National Meeting

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Flavylium polymethine fluorophores for multiplexed in vivo imaging with shortwave infrared light