The use of two fluorophores which absorb and emit at different wavelengths allows a surgeon to distinguish a cancerous tumor from the surrounding healthy tissue, which is imperative for improved navigation during surgery. Fluorescence-guided surgery is enhanced through the use of dyes which absorb and emit in the near-infrared region, where background signal and scattering are minimized. Our lab has developed a non-covalent pre-assembly method where a tetralactam macrocycle with appended targeted ligands is threaded by a near-infrared fluorescent squaraine dye. Previous work has used a tetralactam macrocycle with anthracene sidewalls and squaraine dyes which absorb near 700 nm. While the anthracene macrocycle is a very useful host for squaraine dyes, it often experiences poor solubility and may be oxidized by reactive oxygen species in biological systems. This presentation will describe the supramolecular properties of a new tetralactam macrocycle with 2,3,5,6-tetramethylbenzene sidewalls: specifically, the association thermodynamics and kinetics with squaraine dyes that absorb at 700 or 800 nm. Both sets of dyes thread this new macrocycle with enough kinetic stability to prevent dethreading over the lifetime of a biological imaging experiment. The use of these pre-assembled fluorescent probes for paired-agent imaging will be discussed.

Programmed assembly of near-infrared fluorescent molecular probes

2019 Spring National Meeting

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