To Fluoresce or Not to Fluoresce: An Investigation of the NDA/CN Reaction

Description:
Primary amines are ubiquitous in biological systems and responsible for countless important processes including neurotransmission and cell signaling. These molecules have been sensitively detected via fluorescence after their reaction with the fluorogenic reagent naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide through the formation of fluorescent N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives. However, practically we have observed several challenges in routine use of this reaction: (1) amine-specific differences in both time to reach maximum fluorescence and fluorescence stability over time, and (2) select amines do not generate appreciable fluorescence, including dopamine and serotonin, important neurotransmitters that are associated with many neurological disease states. To interrogate these complications and provide improvements to this reaction, we screened a cohort of primary amines for their fluorescence characteristics under various conditions using fluorescence spectroscopy and their structure using nuclear magnetic resonance spectroscopy. We determined structural characteristics implicated in amine-specific slower reaction kinetics and fluorescence decline over time, and provide easy-to-employ strategies for overcoming these challenges. Finally, we propose structural characteristics implicated in the lack of fluorescence in select CBI-amines, and develop methods to recover their fluorescence. These strategies will be employed in future microfluidic separations to provide better quantitative data on a broader range of primary amines in biological systems implicated in neurological disorders.

Speaker: Rachel Saylor - Oberlin College