Issue 15, 2019

DANPY (dimethylaminonaphthylpyridinium): an economical and biocompatible fluorophore


Dyes with nonlinear optical (NLO) properties enable new imaging techniques and photonic systems. We have developed a dye (DANPY-1) for photonics applications in biological substrates such as nucleic acids; however, the design specification also enables it to be used for visualizing biomolecules. It is a prototype dye demonstrating a water-soluble, NLO-active fluorophore with high photostability, a large Stokes shift, and a favorable toxicity profile. A practical and scalable synthetic route to DANPY salts has been optimized featuring: (1) convergent Pd-catalyzed Suzuki coupling with pyridine 4-boronic acid, (2) site-selective pyridyl N-methylation, and (3) direct recovery of crystalline intermediates without chromatography. We characterize the optical properties, biocompatibility, and biological staining behavior of DANPY-1. In addition to stability and solubility across a range of polar media, the DANPY-1 chromophore shows a first hyperpolarizability similar to common NLO dyes such as Disperse Red 1 and DAST, a large two-photon absorption cross section for its size, substantial affinity to nucleic acids in vitro, an ability to stain a variety of cellular components, and strong sensitivity of its fluorescence properties to its dielectric environment.

Graphical abstract: DANPY (dimethylaminonaphthylpyridinium): an economical and biocompatible fluorophore

Supplementary files

Article information

Article type
13 Oct 2018
19 Feb 2019
First published
19 Mar 2019
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2019,17, 3765-3780

DANPY (dimethylaminonaphthylpyridinium): an economical and biocompatible fluorophore

L. E. Johnson, J. S. Kingsbury, D. L. Elder, R. A. Cattolico, L. N. Latimer, W. Hardin, E. De Meulenaere, C. Deodato, G. Depotter, S. Madabushi, N. W. Bigelow, B. A. Smolarski, T. K. Hougen, W. Kaminsky, K. Clays and B. H. Robinson, Org. Biomol. Chem., 2019, 17, 3765 DOI: 10.1039/C8OB02536C

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