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Published on: July 6, 2016
A General Strategy To Access Fluorogenic Heptamethine Cyanines through Polymethine Reactivity
Buddhini D Kumarasiri1, Katie Jeevaratnam1, Daniel Wherritt1
1Department of Chemistry, The University of Texas at San Antonio, 1 UTSA Circle, San Antonio, Texas 78249, United States.
Abstract:
Fluorogenic heptamethine cyanines are highly desirable for biomedical imaging, yet there are limited strategies to develop them. Here, we report a polymethine reactivity-based approach in which a meso-carboxylate undergoes intramolecular nucleophilic attack at the γ-position, forming a cyclized structure that disrupts π-conjugation. These cyclizing Cy7 (c-Cy7) dyes have a solvent-dependent equilibrium between open (fluorescent) and closed (nonfluorescent) forms in polar and nonpolar solvents, respectively. Indolenine substitution can modulate cyclization equilibrium.

