RESUMEN
We have devised a new caged GABA based on ruthenium bipyridyl coordination chemistry. This phototrigger delivers GABA upon irradiation with wavelengths up to 532 nm undergoing heterolytic photocleavage, in a clean and very fast (a few nanoseconds) photoreaction. With an absorptivity coefficient ε(MAX) = 5300 M(-1) cm(-1) at 447 nm and a quantum efficiency φ ~ 0.09, RuBiGABA-2 is among the most active caged-GABAs, especially at long wavelengths. This highly hydrophilic caged GABA can be synthesized in a simple one-pot reaction. The synthesis, chemical characterization and photochemical properties are presented. Finally, the usefulness of this caged compound is demonstrated by photodelivering free GABA on leech motoneurons.
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2,2'-Dipiridil/análogos & derivados , GABAérgicos/administración & dosificación , Compuestos Organometálicos/química , Fosfinas/química , Ácido gamma-Aminobutírico/administración & dosificación , 2,2'-Dipiridil/química , Animales , GABAérgicos/química , GABAérgicos/farmacología , Ganglios/citología , Ganglios/efectos de los fármacos , Interacciones Hidrofóbicas e Hidrofílicas , Sanguijuelas/citología , Sanguijuelas/efectos de los fármacos , Luz , Fotólisis , Ácido gamma-Aminobutírico/análogos & derivados , Ácido gamma-Aminobutírico/farmacologíaRESUMEN
This is a highlight on the paper by Bonnet et al.: A Lock-and-Kill Anticancer Photoactivated Chemotherapy Agent. which constitutes an important step toward establishing photoactivated chemotherapy (PACT) as a widespread tool to treat different health issues, specially tumors. PACT can be a useful technique to deliver already tested drugs, where the effect of the desired molecule is directed only to its target after light irradiation, even in the cases in which it is difficult to achieve a precise delivery in the desired organ or tissue. Ruthenium-polipyridyl caged-compounds are near ideal devices to deliver a drug in that precise fashion, albeit they usually fail in revealing their actual location due to their weak light emission properties. The mentioned work introduces a simple and clever idea: the use of a covalently linked fluorophore to map the caged-compounds in-vivo distribution prior to the eventual irradiation to activate the chemotherapy.
Asunto(s)
Antineoplásicos , Neoplasias , Rutenio , Humanos , Preparaciones Farmacéuticas , Antineoplásicos/uso terapéuticoRESUMEN
We describe a complete system for optical pH manipulation and imaging. The system consists of a photoactive Ruthenium complex capable of inducing a change of more than 5 pH units at the nanosecond time scale. A compatible imaging system acquires microscopic pH images at 1200 fps using a nonexpensive commercial digital camera and an LED illumination system. We use the system as a superb tool to investigate flow in Flow Injection Analysis (FIA) models.
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Photoreactive surfaces derived from a new photocleavable surface modification agent and with photosensitivity in the Vis and IR region are described. A ruthenium(II) caged aminosilane, [Ru(bpy)(2)(PMe(3))(APTS)](PF(6))(2), was synthesized and attached to silica surfaces. Light irradiation removed the cage and generated surface patterns with reactive amine groups. The photosensitivity of this compound under single (460 nm) and two-photon (900) excitation is demonstrated. Functional patterns with site-selective attachment of other molecular species are described.
RESUMEN
The coordination of a modified rhodamine B (Rhod) to a bis-bipyridine ruthenium (ii) (Ru-bpy) phototrigger complex enables a photodissociation reaction at longer wavelengths through enhanced absorption of green light (532 nm). The very high molar absorptivity of rhodamine (â¼10(5) M(-1) cm(-1)) and the high quantum efficiency of Förster resonance energy transfer (FRET) from rhodamine to the Ru-bpy center (0.84) result in an unusually high photosensitivity and uncaging cross-section of the Ru-bpy-rhodamine complex at longer wavelengths.
RESUMEN
We describe in this paper the properties of [Ru(II/III)(bpy)(2)ClL](+1/+2) and [Ru(II/III)(bpy)(2)L(2)](+2/+3). L = ditolyl-3-pyridylamine (dt3pya) is a redox active ligand related to triarylamines, which is very similar to 3-aminopyridine except for the reversible redox behavior. The monosubstituted complex shows a metal-to-ligand charge-transfer (MLCT) at 502 nm, and reversible waves in acetonitrile at E(0)(Ru(III/II)) = 1.07 V, E(0)(L(+/0)) = 1.46 V (NHE). The disubstituted complex shows an MLCT at 461 nm, a photorelease of dt3pya with quantum yield of 0.11 at 473 nm, and two reversible one-electron overlapped waves at 1.39 V associated with one of the ligands (1.37 V) and Ru(III/II) (1.41 V). Further oxidation of the second ligand at 1.80 V forms a 2,2'-bipiridine derivative, in an irreversible reaction similar to dimerization of triphenylamine to yield tetraphenylbenzidine. In the dioxidized state, the spectroelectrochemistry of the disubstituted complex shows a ligand-to-ligand charge transfer at 1425 nm, with a transition moment of 1.25 Å and an effective two-state coupling of 1200 cm(-1). No charge transfer between ligands was observed when Ru was in a 2+ oxidation state. We propose that a superexchange process would be involved in ligand-metal-ligand charge transfer, when ligands and metals are engaged in complementary π interactions, as in metal-ligand-metal complexes. Best orbital matching occurs when metallic donor fragments are combined with acceptor ligands and vice versa. In our case, Ru(III) bridge (an acceptor) and two dt3pya (donors, one of them being oxidized) made the complex a Robin-Day Class II system, while the Ru(II) bridge (a donor, reduced) was not able to couple two dt3pya (also donors, one oxidized).
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We demonstrate the possibility of tuning the degree of functionalization of a surface using photoactivatable chemistries and controlled light exposure. A photosensitive organosilane with a protected amine terminal group and a tetraethyleneglycol spacer was synthesized. A o-nitrobenzyl cage was used as the photoremovable group to cage the amine functionality. Surfaces with phototunable amine densities were generated by controlled irradiation of silica substrates modified with the photosensitive anchor. Protein layers with different densities could be obtained by successive coupling and assembly steps. Protein surface concentrations were quantified by reflectance interference. Our results demonstrate that the protein density correlates with the photogenerated ligand density. The density control was proved over four coupling steps (biotin, SAv, (BT)tris-NTA, MBP, or GFP), indicating that the interactions between underlying layer and soluble targets are highly specific and the immobilized targets at the four levels maintain their full functionality. Protein micropatterns with a gradient of protein density were also obtained.
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Luz , Fármacos Fotosensibilizantes/química , Proteínas/química , Procesos Fotoquímicos , Fármacos Fotosensibilizantes/síntesis química , Propiedades de SuperficieRESUMEN
Background: The high COVID-19 dissemination rate demands active surveillance to identify asymptomatic, presymptomatic, and oligosymptomatic (APO) SARS-CoV-2-infected individuals. This is of special importance in communities inhabiting closed or semi-closed institutions such as residential care homes, prisons, neuropsychiatric hospitals, etc., where risk people are in close contact. Thus, a pooling approach-where samples are mixed and tested as single pools-is an attractive strategy to rapidly detect APO-infected in these epidemiological scenarios. Materials and Methods: This study was done at different pandemic periods between May 28 and August 31 2020 in 153 closed or semi-closed institutions in the Province of Buenos Aires (Argentina). We setup pooling strategy in two stages: first a pool-testing followed by selective individual-testing according to pool results. Samples included in negative pools were presumed as negative, while samples from positive pools were re-tested individually for positives identification. Results: Sensitivity in 5-sample or 10-sample pools was adequate since only 2 Ct values were increased with regard to single tests on average. Concordance between 5-sample or 10-sample pools and individual-testing was 100% in the Ct ≤ 36. We tested 4,936 APO clinical samples in 822 pools, requiring 86-50% fewer tests in low-to-moderate prevalence settings compared to individual testing. Conclusions: By this strategy we detected three COVID-19 outbreaks at early stages in these institutions, helping to their containment and increasing the likelihood of saving lives in such places where risk groups are concentrated.
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We describe the synthesis and characterization of a ruthenium-bipyridyl complex bearing a rhodamine-based fluorescent ligand. The complex is weakly fluorescent due to the quenching of rhodamine. Upon irradiation of the MLCT band it releases rhodamine in a fast and clean heterolytic reaction, increasing its fluorescence nearly 6-fold and making it the first visible-light activatable fluorophore based in transition metal chemistry. These properties and its lack of toxicity make it a good candidate for its use as a biologically friendly caged fluorescent probe. The use of this probe as a neuronal marker, and as a flow profiler in a thin, planar cavity and in a model flow injection analysis (FIA) is demonstrated.
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Serotonin, or 5-hydroxytryptamine (5HT), is an important neurotransmitter in the nervous system of both vertebrates and invertebrates. Deficits in 5HT signaling are responsible for many disabling psychiatric conditions, and its molecular machinery is the target of many pharmaceuticals. We present a new 5HT phototrigger, the compound [Ru(bpy)2(PMe3)(5HT)]2+, where PMe3 is trimethylphosphine. As with other ruthenium-bipyridyl based caged compounds, [Ru(bpy)2(PMe3)(5HT)]2+ presents activity in the visible region of the spectrum. We characterize and discuss the photochemical properties of the caged compound, and demonstrate its use by modulating the excitability of mouse prefrontal principal neurons.
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Luz , Neuronas/efectos de los fármacos , Corteza Prefrontal/efectos de los fármacos , Rutenio/química , Serotonina/química , Animales , Ratones , Neuronas/metabolismo , Corteza Prefrontal/metabolismo , Serotonina/farmacologíaRESUMEN
Octahedral Ru(II) polypyridyl complexes constitute a superb platform to devise photoactive triggers capable of delivering entire molecules in a reliable, fast, efficient and clean way. Ruthenium coordination chemistry opens the way to caging a wide range of molecules, such as amino acids, nucleotides, neurotransmitters, fluorescent probes and genetic inducers. Contrary to other phototriggers, these Ru-based caged compounds are active with visible light, and can be photolysed even at 532 nm (green), enabling the use of simple and inexpensive equipment. These compounds are also active in the two-photon regime, a property that extends their scope to systems where IR light must be used to achieve high precision and penetrability. The state of the art and the future of ruthenium polypyridyl phototriggers are discussed, and several new applications are presented.
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We report the synthesis, characterization and applications of a ruthenium-bipyridine based caged nicotine. The complex [Ru(bpy)(2)(nic)(2)](2+) (where bpy = 2,2' bipyridine and nic = nicotine (3-[(2S)-1-methylpyrrolidin-2-yl] pyridine)) releases nicotine with a quantum yield Ï = 0.23 upon irradiation with biologically harmless, blue (473 nm) or green (532 nm) light. The photolysis reaction is clean and very fast, with a time constant of 17 ns. The synthesis is simple and the obtained compound is characterized by NMR, UV-Vis spectroscopy and cyclic voltammetry. We find that this compound is active in biological systems, being able to elicit action potentials in leech neurons.
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Luz , Nicotina/química , Nicotina/farmacología , Animales , Electrofisiología , Sanguijuelas/citología , Espectroscopía de Resonancia Magnética , Modelos Químicos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Fotoquímica/métodos , Fotólisis , Rutenio/químicaRESUMEN
We have developed a system that allows focal drug application for cell culture microscopy. Single-cell drug delivery is achieved through the insertion of a patch-clamp-like micropipette in a microenvironment-controlled chamber mounted on a standard 35-mm Petri dish. The system has precise control of temperature, CO(2) concentration, and humidity, while preventing contamination during experiments. The use of standard Petri dishes allows long-term experiments by alternating in situ microscopy with incubator growth. Modern biological long-term experiments such as the characterization of drug effects on cell movement, axonal guidance, mitosis, apoptosis, differentiation, or volume regulation can be performed. The chamber is compatible with any inverted microscope without significant modifications.
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Sistemas de Liberación de Medicamentos/instrumentación , Microscopía por Video/instrumentación , Animales , Células Cultivadas , Cricetinae , Sistemas de Liberación de Medicamentos/métodos , Diseño de Equipo , Factores de TiempoRESUMEN
Temperature imaging based on the fluorescence of the complex [Ru(bpy)3]2+ is described. The method allows precise temperature measurement on unidimensional flow injection reactors and bidimensional measurement on dishes for biological and biochemical assays. The fluorescence dependence on temperature is linear, achieving a resolution of 0.05 K with a simple two-point calibration. The large Stokes shift of [Ru(bpy)3]2+ makes it easy to use a simple CCD camera without special filters. Large or small area fields can be achieved by changing the optics of the camera. High spatial resolution is possible by using any fluorescence microscope.