Photoactivatable Fluorophores

Abstract

Photoactivatable fluorophores switch from a nonemissive to an emissive state upon illumination at an activating wavelength and then emit after irradiation at an exciting wavelength. The interplay of such activation and excitation events can be exploited to switch fluorescence on in a defined region of space at a given interval of time. In turn, the spatiotemporal control of fluorescence translates into the opportunity to implement imaging and spectroscopic schemes that are not possible with conventional fluorophores. Specifically, photoactivatable fluorophores permit the monitoring of dynamic processes in real time as well as the reconstruction of images with subdiffraction resolution. These promising applications can have a significant impact on the characterization of the structures and functions of biomolecular systems. As a result, strategies to implement mechanisms for fluorescence photoactivation with synthetic fluorophores are particularly valuable. In fact, a number of versatile operating principles have already been identified to activate the fluorescence of numerous members of the main families of synthetic dyes. These methods are based on either the irreversible cleavage of covalent bonds or the reversible opening and closing of rings. This paper overviews the fundamental mechanisms that govern the behavior of these photoresponsive systems, illustrates structural designs for fluorescence photoactivation, and provides representative examples of photoactivatable fluorophores in actions.

A Photoswitchable Fluorophore for the Real‐Time Monitoring of Dynamic Events in Living Organisms

“…Additionally, modest illumination intensities for short times are generally sufficient for activation and the presence of molecular oxygen, or any other co‐reactant, is not necessary to switch fluorescence on. Because of these evident advantages, photoactivatable fluorophores are becoming invaluable probes to track fluid dynamics in microstructured channels, translational diffusion in soft matrices, and translocating species in biological specimens …”

“…Additionally,m odesti llumination intensities for short times are generallys ufficientf or activationa nd the presence of molecular oxygen, or any other co-reactant, is not necessary to switch fluorescenceo n. Becauseo ft hese evident advantages, photoactivatable fluorophores are becoming invaluablep robes to track fluid dynamics in microstructured channels, translational diffusion in soft matrices, and translocatings pecies in biological specimens. [10][11][12][13] The potentialo fp hotoactivatable fluorophores to investigate biological processes was recognized in early studies aimed at monitoring the expression of transcription factorsi n fruit-flye mbryos. [14] These seminalr eports demonstrated that the photoinduced activation of ac aged fluorescein-dextran conjugate can be exploited to track engrailed expression in fixed and immunolabeled embryos and suggested the possible use of these photoresponsive constructs to probe cell dynamics in living organisms.…”

Rational Design of Latent Fluorophores from Water‐Soluble Hydroxyphenyltriazine Dyes Suitable for Lipase Sensing

“…[1,2] A specific functionality (typically an aniline or a phenol) of these fluorescent organic dyes is masked by linking a blocking subunit that quenches fluorescence or inhibits, for instance, proton transfer in the excited state. [3] Irreversible unmasking (decaging) by a specific chemical or physical event elicits recovery of the fluorescence and can be used as a reporter for enzyme activity, [4] as an imaging tool, [5] or for sensing specific analytes.…”

Intracellular Photoactivation and Quantification Using Fluorescence Microscopy: Chemical Tools and Imaging Approaches

“…[11,12] Many photoremovable groups have been applied to the activation of fluorophores. [13,14] One reason is that it is experimentally convenient to evaluate the properties of new photoremovable groups when the released molecule becomes colored and/or fluorescent. In addition, photoactivatable fluorophores possess other New Faculty iN SwitzerlaNd CHIMIA 2016, 70, No.…”