Bifunctional Gd(III) and Tb(III) chelates based on a pyridine–bis(iminodiacetate) platform, suitable optical probes and contrast agents for magnetic resonance imaging. (19th March 2014)

• Record Type: Journal Article
• Authors: Laurent, Sophie; Vander Elst, Luce; Galaup, Chantal; Leygue, Nadine; Boutry, Sébastien; Picard, Claude; Muller, Robert. N.
• Is Part Of: Contrast media & molecular imaging. Volume 9:Number 4(2014:Jul./Aug.)
• Page Start: 300
• Page End: 312
• Publication Date: 2014-03-19
• Subjects: Diagnostic imaging -- Periodicals; Magnetic resonance imaging -- Periodicals; Contrast media (Diagnostic imaging) -- Periodicals; Contrast Media -- Periodicals; Diagnostic Imaging -- Periodicals; Substances de contraste -- Périodiques; Diagnostics moléculaires -- Périodiques; Imagerie médicale; Substance de contraste; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.0754
• DOI: 10.1002/cmmi.1576
• Languages: English
• ISSNs: 1555-4309

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>To study the physicochemical properties of lanthanide complexes derived from a bifunctional chelating agent based on a PMN‐tetraacetic acid moiety {PMN‐tetraacetic acid (1): [2, 6‐pyridinediyl<italic>bis</italic>(methylene nitrilo)‐tetraacetic acid]}, 4‐carboxylic acid substituted pyridine derivative (2) was synthesized. This ligand forms heptadentate (N<sub>3</sub>O<sub>4</sub>) Ln(III) complexes (Ln = Gd, Eu, Tb), with two water molecules completing the inner coordination sphere of the metal. The parameters that govern the relaxivity of the Gd(III) complex and the luminescence of Eu(III) and Tb(III) complexes were obtained by <sup>17</sup>O and <sup>1</sup>H NMR studies and time‐resolved fluorescence experiments, respectively. The gadolinium and terbium complexes show interesting properties either for MRI or FOR optical imaging; that is, for the Gd complex, a high proton relaxivity (<italic>r</italic><sub>1</sub> = 6.4 s<sup>−1</sup> m<sc>m</sc><sup>−1</sup> at 20 MHz) with short water residence time (<italic>τ</italic><sub>M</sub> = 38.5 ns); for the Tb complex, a luminescence lifetime of 1.22 ms at room temperature and a luminescence quantum yield of 10%. The kinetic stability of these complexes toward blood protein, cation or bioactive oxyanion was also examined. The Gd(2)(H<sub>2</sub>O)<sub>2</sub> complex does not interact with human serum albumin, but undergoes a transmetalation reaction with Zn(II) in a phosphate buffer solution (pH 7.4), rather similar to that of Gd–DTPA–BMA(H<sub>2</sub>O). On the other hand, as observed for Eu and Tb complexes, these chelates do not form ternary complexes with bidentate anions such as <sc>l</sc>‐lactate, citrate or carbonate. Finally, a phosphatidylserine‐specific hexapeptide (TLVSSL) was grafted on Gd or Tb chelates, and the Gd–peptide conjugate was used <italic>in vitro</italic> for targeting apoptotic cells. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>