1,720,971 research outputs found
ADDUCTS BETWEEN MAGNETIC RESONANCE SHIFT REAGENTS AND SUBSTRATES CONTAINING EXCHANGEABLE PROTONS FOR "CEST" APPLICATIONS
No full textDisclosed are CEST paramagnetic agents comprising a substrate (SH) containing mobile protons bonded to a paramagnetic chelate (SR) containing a metal selected from iron (ii) (high-spin configuration), iron (iii), cobalt (ii), rhodium (ii), copper (ii), nickel (ii), cerium (iii), praseodymium (iii), neodymium (iii), dysprosium (iii), erbium (iii), terbium (iii), holmium (iii), thulium (iii), ytterbium (iii) and europium (iii)
Unfolding of the loggerhead sea turtle (Caretta caretta) myoglobin: A H-1-NMR and electronic absorbance study
No full textGadolinium-doped LipoCEST agents: a potential novel class of dual 1H-MRI probes
No full textA novel class of paramagnetic liposome-based systems acting as dual T1 and CEST 1H-MRI contrast agents is described. The vesicles contain a shift reagent in the aqueous core and a Gd-complex on the external surface conjugated through a biodegradable linker. As such, the probe can generate T1 contrast only, but after the cleavage and removal of the Gd-coating, the CEST contrast is switched on
Evidence for in vivo macrophage mediated tumor uptake of paramagnetic/fluorescent liposomes
No full textLanthanide-Loaded Paramagnetic Liposomes as Switchable Magnetically Oriented Nanovesicles
No full textOsmotically shrunken liposomes loaded with paramagnetic lanthanide(III) complexes orient in a static magnetic field according to the sign of their magnetic susceptibility anisotropy (Δχ). The magnitude and sign of Δχ are modulated by the magnetic properties of the LnIII ion, by the structural characteristics of the metal chelate, and by the stereochemical arrangement of the lipophilic substituents
Combined NMR, DFT and X-ray studies highlight structural and hydration changes of [Ln(AAZTA)]- complexes across the series
Get PDFWe report a detailed structural study of [Ln(AAZTA)]- complexes by using a combination of experimental and theoretical tools. The analysis of the 1H NMR paramagnetic shift of the methyl peak across the series suggests that a structural change occurs between Ho and Er. Chemical exchange saturation transfer experiments were subsequently used to determine the number of coordinated water molecules and their corresponding exchange rates kex at 278 K. The Z-spectra recorded for the Ho(iii) complex present two signals that confirm the presence of two coordinated water molecules, which are endowed with rather different exchange rates: 5.8(±3.0) × 103 and 8.1(±0.5) × 104 s-1. On the contrary, the Er(iii) and Tm(iii) complexes present a single signal in the Z-spectra. The exchange rate of the coordinated water molecule(s) decreases markedly across the series from Gd(iii) to Yb(iii). DFT calculations support the change in hydration number by the end of the lanthanide series, which is the result of an increased steric compression around one of the coordinated water molecules on decreasing the size of the metal ion. X-ray diffraction studies on the Er(iii) complex confirm the presence of a single inner-sphere water molecule and the dodecahedral coordination environment of the metal ion
Paramagnetic Liposomes as Innovative Contrast Agents for Magnetic Resonance (MR) Molecular Imaging Applications
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Determination of water permeability of paramagnetic liposomes of interest in MRI field
No full textThe water permeability of various liposome membranes has been determined at 298 K by measuring the NMR longitudinal water proton relaxation rate of vesicles encapsulating the clinically approved Gd-HPDO3A complex (HPDO3A = 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid). Two basic formulations based on DPPC (dipalmitoylphosphatidylcholine) and POPC (palmitoyl-oleylphosphatidylcholine) phospholipids were selected and investigated. Furthermore, the permeability changes caused by the membrane incorporation of amphiphiles like cholesterol and/or metal complexes of interest for designing improved liposome-based MRI contrast agents, were also investigated. The incorporation of cholesterol and metal complexes bearing C18 saturated chains in POPC-based liposomes reduces the water diffusivity across the membrane bilayer. On the contrary, the incorporation of a macrocyclic metal complex bearing four C12 alkylic chains, one for each coordination arm of the ligand, considerably enhances the water permeability in DPPC-based liposomes. Finally, it is reported that the permeability of POPC-based bilayer is increased when the liposomes are subjected to an osmotic stress
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