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Biomedical subjects

Roberto Etchenique

Publications and source records attributed to Roberto Etchenique.

5 recordsLinked to original sources
PubMed2006

1D and 2D temperature imaging with a fluorescent ruthenium complex.

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.

Journal Article↗
PubMed2006

Ruthenium(II) bipyridyl complexes as photolabile caging groups for amines.

The synthesis and characterization of a series of ruthenium bis(bipyridine) complexes where the inorganic moiety acts as a photolabile protecting group is described. Complexes of the type [Ru(bpy)2L2]+ where bpy = 2,2'-bipyridine and L = butylamine, gamma-aminobutyric acid, tyramine, tryptamine, and serotonin were studied by nuclear magnetic resonance, cyclic voltammetry, and electronic absorption spectroscopy. In all cases, ligands are coordinated by the amine group. The complexes are stable in water for several days and deliver one molecule of ligand upon irradiation with visible light (450 nm). These properties make them suitable for their use as biological caged compounds.

2,2'-Dipyridyl↗
PubMed2003

A new strategy for neurochemical photodelivery: metal-ligand heterolytic cleavage.

A new strategy to build caged-compounds is presented. The approach is based on heterolytic photocleavage of a metal-ligand bond in a coordination compound. A ruthenium polypyridine complex, containing the neurocompound 4-amino pyridine (4AP) is used as the core of the phototrigger. The biomolecule is released by irradiation with visible light (>480 nm). The liberated 4AP promotes the activation of a leech neuron by means of blocking its K+ channels. The syntesis, characterization, and the inherent advantages of this method are discussed.

2,2'-Dipyridyl↗
PubMed2002

Viscoelasticity in the diffuse electric double layer.

The electroacoustical impedance of the quartz crystal microbalance (QCM) in contact with aqueous electrolyte solutions was measured using the transfer function method in a flow injection system . Measurements of both components of the impedance of the QCM, the resistance R and the inductive reactance XL, have been performed for modified and bare gold and silver surfaces and for different concentrations of several aqueous electrolyte solutions. For the experimental concentration range of 0-50 mM, unexpectedly the QCM impedance does not follow the Kanazawa equation, as is usual for bulk newtonian liquids. This behavior indicates the presence of a nanometric sized viscoelastic layer between the piezoelectric crystal and the bulk electrolyte solution. This layer can only be identified as the Gouy-Chapman diffuse double layer (DDL). Its elasticity and viscosity have been estimated by the measurement of R and XL. The viscoelasticity of the DDL appears to be independent of the chemical nature of the surface and of the solution viscosity but strongly dependent on the surface charge, the bulk electrolyte concentration and the dielectric constant of the solvent.

Journal Article↗