Imaging of cells and tissues using light beyond the visible range is advantageous because there are few endogenous molecules capable of absorbing or emitting at these longer wavelengths. This results in lower phototoxicity and higher signal-to-noise as there is less attenuation of the optical signal and less interference from autofluorescence. Suitable fluorescent dyes in this wavelength region have long been dominated by cyanines, a class of fluorophore that typically has low photostability and large size. The development of smaller and more photostable dyes in this wavelength region is therefore highly desirable. In this proposal, we will explore the scope of electron donors and the incorporation of LUMO-lowering substitutions in different positions and dyes, with the goal of optimized compact near-IR fluorophores, quenchers, and fluorogenic probes for a wide range of applications.

Fluorescent dyes are great probes for studying biology, as they can be used to tell us where specific molecules are located, and often what they are doing, simply by shining light on the dye. However, it is difficult to make dyes that are small, stable to bright light, and easy to see in colored liquids like blood. Our work studies new strategies to create brighter, more compact and photostable fluorescent dyes that can be used to detect important molecules in complex biological environments.