Search results for "Fluorescence"
showing 10 items of 2463 documents
Sensitization of nanocrystalline TiO2 with 3,4,9,10-perylene tetracarboxylic acid
2014
Optical properties of 3,4,9,10-perylene tetracarboxylic acid (PTCA) in the presence of nanocrystalline TiO2 (nominal diameter 15 nm) have been investigated in ethanol solution and in the solid state by UV-Vis absorption spectroscopy and steady-state and time-resolved fluorescence. Experimental results show that, in ethanol, the presence of TiO2 nanoparticles causes significant changes in the typical absorption and fluorescence bands of PTCA and in the fluorescence relaxation time. Similar effects are also detected in solid samples, obtained by electrospray deposition technique. The nonlinear optical properties of the PTCA-TiO2 in ethanol solutions were investigated using the single-beam Z-s…
Inhibitory activities of short linear motifs underlie Hox interactome specificity in vivo
2015
Hox proteins are well-established developmental regulators that coordinate cell fate and morphogenesis throughout embryogenesis. In contrast, our knowledge of their specific molecular modes of action is limited to the interaction with few cofactors. Here, we show that Hox proteins are able to interact with a wide range of transcription factors in the live Drosophila embryo. In this context, specificity relies on a versatile usage of conserved short linear motifs (SLiMs), which, surprisingly, often restrains the interaction potential of Hox proteins. This novel buffering activity of SLiMs was observed in different tissues and found in Hox proteins from cnidarian to mouse species. Although th…
Hsa-miR-30d, secreted by the human endometrium, is taken up by the pre-implantation embryo and might modify its transcriptome.
2015
During embryo implantation, the blastocyst interacts with and regulates the endometrium, and endometrial fluid secreted by the endometrial epithelium nurtures the embryo. Here, we propose that maternal microRNAs (miRNAs) might act as transcriptomic modifier of the pre-implantation embryo. Microarray profiling revealed that six of 27 specific, maternal miRNAs were differentially expressed in the human endometrial epithelium during the window of implantation – a brief phase of endometrial receptivity to the blastocyst – and were released into the endometrial fluid. Further investigation revealed that hsa-miR-30d, the expression levels of which were most significantly upregulated, was secreted…
γ2-Adaptin is functioning in the late endosomal sorting pathway and interacts with ESCRT-I and -III subunits.
2010
Abstractγ2-Adaptin is a clathrin adaptor-related protein with unclear physiological function. Previous studies indicated that γ2-adaptin might act within the multivesicular body (MVB) protein-sorting pathway that is central to receptor down-regulation, lysosome biogenesis, and budding of enveloped viruses. Here, we have analyzed the effects of excess and deficit γ2-adaptin on exogenous and endogenous MVB cargoes and on the MVB machinery itself. Foreign cargoes, like retroviral Gags, are entrapped by overexpressed γ2-adaptin in detergent-insoluble polymers and blocked in budding. When viral budding involves MVB/endosomal structures, excess γ2-adaptin acts by accelerating lysosomal Gag destru…
Tumour vascularization via endothelial differentiation of glioblastoma stem-like cells
2010
Glioblastoma is a highly angiogenetic malignancy, the neoformed vessels of which are thought to arise by sprouting of pre-existing brain capillaries. The recent demonstration that a population of glioblastoma stem-like cells (GSCs) maintains glioblastomas indicates that the progeny of these cells may not be confined to the neural lineage. Normal neural stem cells are able to differentiate into functional endothelial cells. The connection between neural stem cells and the endothelial compartment seems to be critical in glioblastoma, where cancer stem cells closely interact with the vascular niche and promote angiogenesis through the release of vascular endothelial growth factor(VEGF) and str…
Geomaterials in green building practices: comparative characterization of commercially available clay-based plasters
2013
Three pre-mixed powdered clay-based (earthen) plasters produced in Europe and specifically designed for wall undercoating were analyzed in this paper. These materials are commercially available and successfully employed in green building practices all over the world. Their compositional and textural characteristics, as well as plastic behaviour were investigated through a multi-analytical approach: X-ray powder diffraction (XRPD), polarized light microscopy (PLM), X-ray fluorescence spectrometry (XRFS), scanning electron microscopy equipped with an energy dispersive spectrometer (SEM-EDS), mercury intrusion porosimetry (MIP), grain-size distribution (GSD) and semi-empirical tests (Atterberg…
Enhancing carbon dots fluorescence via plasmonic resonance energy transfer
2022
Using plasmonic interactions to engineer optical properties at the nanoscale is an important challenge of current photonics. Here we establish a general strategy to enhance the orange emission of carbon dots by coupling them to gold nanoparticles through a polymeric spacer in solution. We exploit the overlap between the surface plasmon resonance of gold and the electronic transitions of carbon dots to achieve a fivefold increase of their fluorescence in the orange region, which is usually very weak. We demonstrate that this enhancement stems from an ultrafast resonance energy transfer from the coherent plasmonic state of the gold nanoantenna to the coupled carbon dot. Our study advances the…
Fluorescence labels as sensors for oxygen binding of arthropod hemocyanins
2004
The molecular basis of high cooperativity in multi-subunit proteins is still unknown in most cases. Oxygen binding by multi-subunit hemocyanins produces two intrinsic spectroscopic signals which are, however, either limited to the UV or are very weak. Here we demonstrate that fluorescence labels emitting in the visible can be used as sensors for cooperative oxygen binding of hemocyanins. Fluorescence resonance energy transfer to the oxygenated active sites quenches the emission of the labels by roughly 50% upon oxygenation of the protein. The labels give strong and photo-stable emission, allowing imaging of single hemocyanin molecules. Therefore, this study opens up a new perspective for in…
Near-infrared emissive bacteriochlorin-diketopyrrolopyrrole triads: Synthesis and photophysical properties
2019
International audience; The synthesis of unprecedented energy transfer triads containing a near-infrared (NIR) emissive bacteriochlorin subunit and two diketopyrrolopyrrole (DPP) moieties linked to each other via ethynyl or zero-carbon spacers is presented. Their optical and fluorescence properties were determined in CHCl3 and toluene. These photophysical measurements highlight the ability of DPP scaffold to act as an effective energy donor, which once excited in the range 450-550 nm resulting nearly exclusively NIR emission of hydroporphyrin (ETE > 96%). Since DPP dyes are valuable structurally tunable fluorophores that may be used in the construction of high-performance multicomponent pho…
Mixing dynamics in uncovered unbaffled stirred tanks
2014
Abstract The present work is aimed at providing experimental information on mixing rates in an unbaffled vessel under free surface vortexing conditions. The planar laser induced fluorescence (PLIF) technique was used for measuring the dispersion dynamics of a passive tracer over a vertical section of the vessel. In agreement with the quite scant literature information available for these systems, results confirm the existence of two well defined, partially segregated, zones that give rise to a double mixing dynamics behavior. A suitable mixing time definition is proposed and applied to a number of experimental runs with different stirrer geometries and agitation speeds. Results confirm that…