A New Class of Stable Heptamethine Cyanine Fluorophores and Biomedical Applications Thereof
Heptamethine cyanines are among the most widely used near-IR fluorophores. The near-IR range (between about 650 nm and 900 nm) is very useful for imaging applications due to the absence of background autofluorescence. Despite extensive use, many of these fluorophores suffer from chemical instability. Specifically, most of the current and commonly used fluorophores undergo a phenoxy to thiol exchange reaction in the presence of primary thiols. This exchange reaction is problematic during conjugation reactions of cysteine containing macromolecules.