A Photoactivatable Far-Red/Near-Infrared BODIPY To Monitor Cellular Dynamics in Vivo

Abstract

A mechanism to photoactivate far-red/near-infrared fluorescence with infinite contrast and under mild visible illumination was designed around the photophysical properties of borondipyrromethene (BODIPY) dyes and the photochemical behavior of oxazine heterocycles. Specifically, the photoinduced and irreversible cleavage of an oxazine ring with a laser line at 405 nm extends the electronic conjugation of a BODIPY chromophore over a 3H-indole auxochrome with a 2-(4-methoxyphenyl)ethenyl substituent in position 5. This structural transformation shifts bathochromically the main absorption band of the BODIPY component to allow the selective excitation of the photochemical product with a laser line of 633 nm and produce fluorescence between 600 and 850 nm. This combination of activation, excitation, and emission wavelengths permits the visualization of the cellular blastoderm of developing Drosophila melanogaster embryos with optimal contrast and essentially no autofluorescence from the biological specimen. Furthermore, the sequential acquisition of images, after the photoactivation event, enables the tracking of individual cells within the embryos in real time. Thus, our structural design and operating principles for the photoactivation of far-red/near-infrared fluorescence can evolve into invaluable probes to monitor cellular dynamics in vivo.

Photopotentiation of the GABA A receptor with caged diazepam

“…The mixing of 1 and 6 in water results in the formation of micellar nanoconstructs (Fig. 1 C, Right), which can transport and deliver effectively the molecule of interest (74), as already demonstrated by recent studies in a biological context (72,73).…”

“…It is evident that the caged molecule should possess, at least in theory, no intrinsic activity toward the GABA A receptor, and analysis of the extensive and discrete list of BDZ structure-activity relationships (69)(70)(71) published over the years suggests that the introduction of such a heterocycle on the iminic part would alter the molecular geometry and shape sufficiently to suppress activity. Additionally, the reliable and extensive use of this caging motif for the synthesis of photoactivatable fluorophores, reported in recent bioimaging studies (72,73), makes it very appealing in a photopharmacological scenario. In fact, the presence of a nitro functionality on the benzooxazine ring confers high photosensitivity to compound 1, which can be used as a "lightsensitive prodrug" of DZP (Fig.…”

Recent chemo‐/biosensor and bioimaging studies based on indole‐decorated BODIPYs

“…developed a novel system in which irreversible cleavage of the oxazine ring within the BODIPY complex using photo‐induction that enabled the residue to interact with the indole molecule and subsequently extend fluorescence excitation and emission spectra. They also tested this controllable system on Drosophila melanogaster embryos, and demonstrated the potential of this system for in vivo applications without any autofluorescence issue . A similar approach was applied to nanoparticles modified using photo‐inducible BODIPY molecules and the indole moiety; biological evaluation of photo‐inducible nanoparticles was evaluated on Caenorhabditis elegans …”

“…[91] In addition, indole molecules have been used to modulate fluorescence properties of the BODIPY conjugates for in vivo imaging. For instance, Sansalone et al [92] developed a novel system in which irreversible cleavage of the oxazine ring within the BODIPY complex using photo-induction that enabled the residue to interact with the indole molecule and subsequently extend fluorescence excitation and emission spectra. They also tested this controllable system on Drosophila melanogaster embryos, and demonstrated the potential of this system for in vivo applications without any autofluorescence issue.…”

“…They also tested this controllable system on Drosophila melanogaster embryos, and demonstrated the potential of this system for in vivo applications without any autofluorescence issue. [92] A similar approach was applied to nanoparticles modified using photoinducible BODIPY molecules and the indole moiety; biological evaluation of photo-inducible nanoparticles was evaluated on Caenorhabditis elegans. [93]…”