Tuning the optical properties of BODIPY dye through Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reaction

Abstract

Borondipyrromethenes (BODIPY) are a class of fluorescent dyes whose fluorescence quantum yields are generally high and independent of the solvent. In this paper, we report the synthesis of a new type of BODIPY compound that carries an azido group on the 3-position of the pyrrole core. The azido group quenches the fluorescence of the dye due to its weak electrondonating effect. The fluorescence of the BODIPY dye can be switched on after reacting with alkynes via a Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reaction. We further demonstrate that this azido-BODIPY compound can be used in the cell imaging applications.

Design strategies for bioorthogonal smart probes

“…Quenching via ICT may also be operant in other scaffolds, such as in azide-functionalized BODIPY, benzothiazole, and carbazoles ( 14–16 ), although other factors may be at play. 64–67 …”

Bioorthogonal fluorescent labels: a review on combined forces

“…They also experienced that the potential byproduct amine derivative is virtually non-fluorescent therefore it has no contribution to the background signal. A selected compound was first evaluated in alkyne-functionalized BSA tagging using CuAAC scheme, then used to label proteoglycans in fixed CL1-5 lung cancer cells, previously incorporated peracetylated alkynyl-N-acetylmannosamine (Ac4ManNAl) and alkynyl-N-acetylgalactosamine (Ac4GalNAl)(Figure 11).Wang and co-workers in 2012 reported another azido-BODIPY derivative(Figure 10, 7), which showed an excellent, 800-fold (although in CHCl3) increase in fluorescence intensity upon reaction with alkynes (reaction with different alkynes: exc 514-522, em 529-538, in MeOH) [86]. KB cells overexpressing folate receptors were treated with terminal alkyne modified folate.…”

Fluorogenic Azidofluoresceins for Biological Imaging

“…Recently, an azido BODIPY probe was reported, but the compound was unstable and unable to specifically react with alkynes on cellular biolmolecules. 6 An alkynyl benzothiazole analog that emits at ~500 nm has been reported but its fluorescence enhancement upon reaction with azides was a modest 3.5-fold in aqueous buffer. 11 A screen of 200 combinations of various alkynyl xanthenes and organic azides produced two reagent pairs that reacted to give a fluorescence enhancement of 10-fold in organic solvent.…”