Synthetic organic dyes are used as ink/paint colorants, antibiotics, laser dyes or food additives. They can also be used as optical “paints” (i.e., fluorophores) in biological contexts, for instance, as contrast agents for imaging. Fluorophores emitting light in the near-infrared (NIR) region provide sensitivity, safety, and deep tissue penetration, but their number is limited.
Jean-Alexandre Richard, Institute of Chemical and Engineering Sciences, Singapore, and colleagues have developed dihydroxanthene (DHX) fluorophores (example pictured) which can serve as chemical biology tools. The team was able to access DHX skeletons bearing an aldehyde at the C4′ position and/or a bromine atom at C6′ in a one-pot process. Functionalization of the products provided analogues that allowed the team to perform a structure-fluorescence relationship study.
The researchers showed preliminary biological applications by preparing water-soluble DHX dyes and demonstrating that protein labeling was possible. This study streamlines the synthesis of hard-to-access NIR-emitting molecules and provides a novel option for fluorescence imaging.
- Synthesis of N,N-Dialkylamino-nor-Dihydroxanthene-Hemicyanine Fused Near-Infrared Fluorophores and Their First Water-Soluble and/or Bioconjugatable Analogues,
Jean-Alexandre Richard, Michelle Jui Hsien Ong, Sylvain Debieu, Mathieu Moreau, Anthony Romieu,
Chem. Asian J. 2017.