16 research outputs found
Magnetic resonance imaginG Contrast agents exEmplified by iron complexes
Nuclear magnetic resonance is already a broadly exploited phenomenon both
in chemistry and medicine. Magnetic resonance imaging is a routine technique in
medical diagnosis readily applied for soft tissues like brain, cardiovascular system
or gastrointestinal tract. Contrast agents stepped into the field and enabled better
recognition of a lesion in the early stage of a disease.
The authors present an introductory description of a fascinating history, classification
of contrast agents followed by the mechanisms of their action. Classes
of positive and negative contrast agents are described. Further discussion is focused
on the T1 (positive) molecular species. The mechanism was divided into (1)
inner sphere, where both direct coordination of water molecule and its presence in
second sphere is considered (Fig. 1) [1] and (2) an outer sphere mechanism which
is assumed for the water molecules diffusing into the surrounding of the paramagnet
[21, 28]. Further, the most important requirements for medical applications are
given. Those are: high relaxivity, charge-osmolality, stability, toxicity via potential
transmetallation of redox activity [42]. Molecular examples are quoted based on
previously investigated iron complexes. Majority of them are iron(III) species [68],
however, some iron(II) compounds like activable, self-immolative or ParaCEST systems
have recently appeared [86, 89]. Iron compounds as positive contrast agents
may soon accompany classic gadolinium complexes
Spectroscopic data for aminophenol ligands, their galactose derivatives and their iron(III) complexes
1H, 13C NMR (FID and processed spectra) and HR-MS spectroscopic data of amino-phenol chelating ligands, their derivatives with B-galactose, N,O-ligands and HR-MS spectra of Fe iron(III) complexes as bioresponsive, smart, enzyme sensitive systemsTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Study on Species of Heavy Lanthanides(III) Chelates Extracted into Organic Phase with 5,7-Dichloro-8-hydroxyquinoline
The nature of species formed in the extraction of lanthanides Ln(III) (where Ln = Tb, Dy, Ho, Er, Tm and Yb) with 5,7-dichloro-8-hydro xyquinoline (HL) in CHCl from water or water-methanol phase was examined. It was stated that during the extraction from water phase the chelates LnL (Tb, Tm), seven-coordinated self-adducts LnL ÷ HL (Er, Ho) or both types of these species (Dy, Yb) were extracted. In the presence of methanol (MeOH) in the aqueous phase the eight-coordinated mixed species of the type LnL·2MeOH were observed
Amalgamation of complex iron(III) ions and iron nanoclusters with MWCNTs as a route to potential T2 MRI contrast agents
Nikodem Kuźnik,1 Mateusz M Tomczyk,1 Marzena Wyskocka,1 Łukasz Przypis,1 Artur P Herman,1 Rafał Jędrysiak,1 Krzysztof K Koziol,2 Slawomir Boncel11Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Faculty of Chemistry, Silesian University of Technology, Gliwice, Poland; 2Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UKAbstract: Iron-filled multiwall carbon nanotubes (Fe@MWCNTs) were functionalized toward a variety of potential magnetic resonance imaging contrast agents. Oxidized Fe@MWNCTs were covered with PEG5000 via direct esterification or using acyl chloride derivatives. Alternatively, the latter were functionalized with an aminophenol ligand (Fe@O-MWCNT-L). Moreover, pristine Fe@MWCNTs were functionalized with N-phenylaziridine groups (Fe@f-MWCNT) via [2+1] cycloaddition of nitrene. All of these chemically modified nanotubes served as a vehicle for anchoring Fe3+ ions. The new hybrids – Fe(III)/Fe@(f-/O-)MWCNTs – containing 6%–14% of the “tethered” Fe3+ ions were studied in terms of the acceleration of relaxation of water protons in nuclear magnetic resonance. The highest transverse relaxivity r2=63.9±0.9 mL mg-1 s-1 was recorded for Fe(III)/Fe@O-MWCNT-L, while for Fe(III)/Fe@f-MWCNT, with r2=57.9±2.9 mL mg-1 s-1, the highest impact of the anchored Fe(III) ions was observed. The T1/T2 ratio of 30–100 found for all of the nanotube hybrids presented in this work is a very important factor for their potential application as T2 contrast agents. Increased stability of the hybrids was confirmed by ultraviolet–visible spectrophotometry.Keywords: multiwall carbon nanotubes, Fe3+, transverse relaxation time T2, MRI contrast agen