A fast ruthenium polypyridine cage complex photoreleases glutamate with visible or IR light in one and two photon regimes

Abstract

We introduce a new caged glutamate, based in a ruthenium bipyridyl core, that undergoes heterolytic cleavage after irradiation with visible light with wavelengths up to 532 nm, yielding free glutamate in less than 50 ns. Glutamate photorelease occurs also efficiently following two-photon (2P) excitation at 800 nm, and has a functional cross section of 0.14 GM.

Multiphoton Reactive Surfaces Using Ruthenium(II) Photocleavable Cages

“…12,16 A value of ε λ ϕ = 631 M −1 cm −1 was obtained. Taking ε 460 ≈ 4000 M −1 cm −1 (reported value from [Ru(bpy) 2 (PMe 3 )(Glu)] in solution 14 ), a quantum yield of 0.16 for the photolysis of the Ru complex at the surface could be estimated. This value agrees with the reported value for [Ru(bpy) 2 (PMe 3 )(Glu)] from solution experiments, ϕ = 0.13 at pH 7 14 and indicates that the uncaging reaction at the surface and in solution proceeds with similar mechanism and characteristics.…”

“…It is important to note that two-photon uncaging of ruthenium bipyridyl complexes in solution has been recently demonstrated and reported. 14,20 In the present work, two-photon uncaging of the modified surface layer was tested by scanning the surface at 900 nm in the presence of water with a high intensity Ti:Sa laser. In order to identify the energy threshold for the cleavage, several squares of 45 μm × 45 μm were written by raster scanning, forming an array of squares exposed at different average intensities (I) (from ∼2 to 75 mW) and irradiation times (t) (between 2 and 62 s).…”

Ruthenium polypyridyl phototriggers: from beginnings to perspectives

“…This is the case of the complex [Ru(bpy) 2 (PMe 3 )(Glu)] (RuBi-Glutamate) [20], capable of photoreleasing the excitatory neurotransmitter glutamate, shown in figure 2. Figure 2a shows the normal bidentate coordination of α-amino acids, in which both the amine and the α-carboxylate group are involved.…”

“…The design of RuBi-GABA [18] and RuBiGlutamate [20] opened a wide spectrum of possibilities to experiment with 1P and 2P active caged versions of the most ubiquitous inhibitory and excitatory neurotransmitters. RuBi-Glutamate appears to be a superb tool to determine circuitry in dense neuronal systems [28][29][30][31][32].…”

Multi-photon excitation in uncaging the small molecule bioregulator nitric oxide

“…The three-dimensional resolution opportunities provided by TPE have extensively been exploited in neuroscience both in tissue samples and in vivo [43][44][45][46][47][48][49][50]. The NIR TPE induced uncaging of neurotransmitters such as glutamate (figure 4) and has allowed the functional mapping of the respective receptors in neurons with high-resolution (μm), sub-cellular precision Figure 4.…”