Sylvestre Gug

Two-photon uncaging: New prospects in neuroscience and cellular biology.

An uncaging process refers to a fast and efficient release of a biomolecule after photochemical excitation from a photoactivatable precursor. Two-photon excitation produces excited states identical to standard UV excitation while overcoming major limitations when dealing with biological materials, like spatial resolution, tissue penetration and toxicity and has therefore been applied to the uncaging of different biological effectors. A literature survey of two-photon uncaging of biomolecules is described in this article, including applications in cellular- and neurobiology.

Molecular Engineering of Photoremovable Protecting Groups for Two-Photon Uncaging†

The photochemical release of theactive molecule is usually induced by an initial one-photonabsorption process, leading to a limited spatial localization ofthe released substance. To overcome this obstacle, two-photon (TP) excitation has recently emerged as a verypromising technique to obtain spatial control.

Live-Cell One- and Two-Photon Uncaging of a Far-Red Emitting Acridinone Fluorophore

Total synthesis and photophysical properties of PENB-DDAO, a photoactivatable 1,3-dichloro-9,9-dimethyl-9H-acridin-2(7)-one (DDAO) derivative of a far-red emitting fluorophore, are described. The photoremovable group of the DDAO phenolic function comprises a donor/acceptor biphenyl platform which allows an efficient (> or = 95%) and rapid (< 15 micros time-range) release of the fluorescent signal and displays remarkable two-photon uncaging cross sections (delta(a) x Phi(u) = 3.7 GM at 740 nm). PENB-DDAO is cell permeable as demonstrated by the triggering of cytoplasmic red fluorescent signal in HeLa cells after one-photon irradiation (lambda(exc) around 360 nm) or by the generation of a red fluorescent signal in a delineated area of a single cell after two-photon photoactivation (lambda(exc) = 770 nm).

Photolabile Glutamate Protecting Group with High One- and Two-Photon Uncaging Efficiencies

A π‐extended [2‐(2‐nitrophenyl)propoxy]carbonyl (NPPOC) derivative has been prepared as an efficient UV and near‐IR photolabile protecting group for glutamate. This glutamate cage compound exhibits efficient photorelease upon one‐photon excitation (εΦ=990 M−1 cm−1 at 315 nm). In addition, it also shows efficient photorelease in activation of glutamate receptors in electrophysiological recordings. Combined with a high two‐photon uncaging cross‐section (δΦ=0.45 GM at 800 nm), its overall properties make this new cage—3‐(2‐propyl)‐4′‐methoxy‐4‐nitrobiphenyl (PMNB)—for glutamate a very promising tool for two‐photon neuronal studies.

Two-photon excitation in life sciences: neurotransmitter and fluorescence uncaging

We describe the molecular engineering of new highly efficient two-photon photolabile cages, based on dissymmetrical donor-acceptor and symmetrical donor-donor systems. Complete characterizations of these new cages, based on a biphenyl, fluorenyl or a 2,5-diphenylthienyl central core will be presented. In vitro photochemistry will be described (uncaging quantum yield, two-photon uncaging action cross-section,...) and we will then focus on biological results obtained in cell culture and on acute brain slices (with glutamate and fluorescence uncaging).

Two-Photon Sensitive Photolabile Protecting Groups From Molecular Engineering to Nano-Structuration

Molecular engineering of efficient two-photon sensitive photolabile protecting groups for neuroscience will be presented as well as their nano-structuration. Application of caged glutamate in brain sciences will be emphasized.