Flavylium- and Silylrhodapolymethines In Excitation Multiplexing

Abstract

Creation of a flavylium polymethine dye set enabled selection of two fluorophores that match common lasers for exciting in the near-IR II region. Using these, researchers cast a broad net to catch any wavelength emission in the near-IR II region, and relied on selective excitation to multiplex; this is a paradigm shift away from multiplexing via discrimination of emission wavelengths. Excitation multiplexing with flavylium dyes is a new and exciting strategy, but not yet a perfect one; it requires discrete water soluble fluorophores, including one that is turned on at 808 nm.

Keywords: dyes and pigments; excitation multiplexing; flavylium; imaging; polymethine dye.

Figure 1.

a) Scheme showing an electromagnetic spectrum showing NIR—I and -II regions. b) Structure of Flav7 (top) and an absorption/emission maxima “map” showing the influence of introducing two dimethylamino substituents at identical places on each flavylium ring. (values shown are in dichloromethane)^[3].

Figure 2.

a) Essentials of excitation-based multiplexing. b) Novel dyes developed to be excited at around 980 and 1064 nm. (values shown are in dichloromethane).^[3]

Figure 3.

Comparison of silylrhodapentamethine and rhodapentamethine dyes (values shown are in dichloromethane).^[4]