Relaxivity Studies on a Gadolinium(III) Complex of a Macrocyclic DTPA Derivative

Zitha-Bovens, Emrin; Elst, Luce Vander; Müller, Robert N.; Bekkum, H. van; Peters, Joop A.

doi:10.1002/1099-0682(200112)2001:12<3101::aid-ejic3101>3.0.co;2-d

Cited by 23 publications

(18 citation statements)

References 16 publications

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“…The temperature was calculated according to a previous calibration with ethylene glycol and methanol [ 28 ]. The samples were measured in 5-mm NMR tubes and were enriched with tert -butanol to allow for the bulk magnetic susceptibility correction [ 29 ]. The 1/ T 1 data were obtained by the inversion recovery method, while the 1/ T 2 data were measured by the Carr–Purcell–Meiboom–Gill spin-echo technique.…”

Section: Methodsmentioning

confidence: 99%

Towards extracellular Ca2+ sensing by MRI: synthesis and calcium-dependent 1H and 17O relaxation studies of two novel bismacrocyclic Gd3+ complexes

et al. 2007

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Two new bismacrocyclic Gd 3+ chelates containing a specific Ca 2+ binding site were synthesized as potential MRI contrast agents for the detection of Ca 2+ concentration changes at the millimolar level in the extracellular space. In the ligands, the Ca 2+ -sensitive BAPTA-bisamide central part is separated from the DO3A macrocycles either by an ethylene (L 1 ) or by a propylene (L 2 ) unit [H 4 BAPTA is 1,2-bis(o-aminophenoxy)ethane-N,N,N 0 ,N 0 -tetraacetic acid; H 3 DO 3 A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid]. The sensitivity of the Gd 3+ complexes towards Ca 2+ and Mg 2+ was studied by 1 H relaxometric titrations. A maximum relaxivity increase of 15 and 10% was observed upon Ca 2+ binding to Gd 2 L 1 and Gd 2 L 2 , respectively, with a distinct selectivity of Gd 2 L 1 towards Ca 2+ compared with Mg 2+ . For Ca 2+ binding, association constants of log K = 1.9 (Gd 2 L 1 ) and log K = 2.7 (Gd 2 L 2 ) were determined by relaxometry. Luminescence lifetime measurements and UV-vis spectrophotometry on the corresponding Eu 3+ analogues proved that the complexes exist in the form of monohydrated and nonhydrated species; Ca 2+ binding in the central part of the ligand induces the formation of the monohydrated state. The increasing hydration number accounts for the relaxivity increase observed on Ca 2+ addition. A 1 H nuclear magnetic relaxation dispersion and 17 O NMR study on Gd 2 L 1 in the absence and in the presence of Ca 2+ was performed to assess the microscopic parameters influencing relaxivity. On Ca 2+ binding, the water exchange is slightly accelerated, which is likely related to the increased steric demand of the central part leading to a destabilization of the Ln-water binding interaction.

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Section: Methodsmentioning

confidence: 99%

Towards extracellular Ca2+ sensing by MRI: synthesis and calcium-dependent 1H and 17O relaxation studies of two novel bismacrocyclic Gd3+ complexes

et al. 2007

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“…chemical shifts, T 1 and T 2 relaxation times) of solutions of the Gd-DO3AP BP complex (87-93 mM, pH = 6 and 7.5) were performed without spin and frequency lock in the temperature range 5-85 • C. 17 O NMR chemical shifts were corrected for the bulk magnetic susceptibility (BMS) contribution by measurement of the difference between chemical shifts of 1 H NMR signals of t-BuOH in the paramagnetic sample and in a sample of t-BuOH in pure water. 51 31 P{ 1 H} T 1 relaxation times of the Ho-DO3AP BP complex in D 2 O (110 mM, pH = 7.0) were measured without spin and frequency lock, with gain set to zero at 25 • C. Obtained data were not corrected for a diamagnetic contribution. 2 H T 1 relaxation times of aqueous solutions of partially deuterated La-DO3AP BP complexes (20-250 mM, pH = 7.5; and 50 mM, pH = 7.5 in the presence of 0.5 equiv.…”

Section: Nmr Spectroscopymentioning

confidence: 99%

Gd(iii) complex of a monophosphinate-bis(phosphonate) DOTA analogue with a high relaxivity; Lanthanide(iii) complexes for imaging and radiotherapy of calcified tissues

et al. 2009

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A new phosphinic-acid DOTA-like ligand, DO3AP(BP), containing a geminal bis(phosphonic acid) moiety as a highly effective bone-seeking group, was synthesized in high yield. Its crystal structure was determined by X-ray analysis. Complexation with lanthanide(iii) ions occurs under mild conditions (pH = 8-9, 25 degrees C, 2-3 h). (1)H, (31)P, and (17)O NMR spectroscopy show that DO3AP(BP) forms nine-coordinated lanthanide(iii) complexes with one water molecule in the first coordination sphere except for Ln = Er-Lu, which have in addition a species without lanthanide(iii)-bound water. Selective formation of only two diastereomers (out of four possible) suggests that the coordinated phosphinate phosphorus atom occurs exclusively in one of the enantiomeric forms. The ratio of the twisted square antiprism (TSA) and square antiprism (SA) diastereomers changes along the lanthanide series; the gadolinium(iii) complex has about 35% of the TSA species. The bis(phosphonate) moiety remains free for anchoring to osseous tissue. The (1)H longitudinal relaxivity of the Gd-DO3AP(BP) complex (r(1) = 7.4 s(-1) mM(-1), 20 MHz, 25 degrees C, pH = 7.5) is unexpectedly high compared to that of other monohydrated chelates of similar size thanks to a significant contribution from the second hydration sphere. The water residence time tau(M)(298) is 198 ns. Further increase in the relaxivity was observed in the presence of Zn(ii), Mg(ii) or Ca(ii) ions, due to formation of coordination polymers. Slowing down of the tumbling rate of the Gd-DO3AP(BP) complex upon adsorption on hydroxyapatite also leads to an increase of the relaxivity (r(1) = 17 s(-1) mM(-1), 20 MHz, 25 degrees C, pH = 7.5).

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“…Biocompatible Gd 3þ complexes are used as relaxation contrast agents [1][2][3][4][5][6][7] (CAs) in about 40% of medical examinations by magnetic resonance imaging (MRI). Paramagnetic CAs have a dominant effect on the T 1 relaxation of the protons of the neighboring water molecules, leading to an enhanced contrast of the tissues where they distribute.…”

Section: Introductionmentioning

confidence: 99%

Simple analytical approximation of the longitudinal electronic relaxation rate of Gd(iii) complexes in solutions

Bélorizky

Fries

2004

Phys. Chem. Chem. Phys.

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More and more sophisticated theoretical models have been developped for a correct description of the relaxation of the electronic spin S ¼ 7/2 of the Gd(III) paramagnetic complexes used as contrast agents in magnetic resonance imaging (MRI). Both the static zero field splitting (ZFS) modulated by the random rotation of the complex and the transient ZFS due to the very fast distortion of this entity must be included in these models. This leads to rather complicated analytical expressions, from which it is difficult to evaluate the respective effects of the physically relevant parameters. However, in the Redfield limit of the theory of electronic spin relaxation, we show that the longitudinal relaxation function G k (t) has a quasi-monoexponential decay characterized by a unique relaxation rate 1/T 1e , which has a simple expression in terms of the applied magnetic field B 0 , of the static and transient ZFS parameters, and of the rotational and vibrational correlation times. For the typical investigated Gd(III) complexes, this expression is shown to have a very satisfactory accuracy for B 0 < 10 T. The various physical parameters as well as the range of validity of the relaxation approximation are discussed in detail. PCCP

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Relaxivity Studies on a Gadolinium(III) Complex of a Macrocyclic DTPA Derivative

Cited by 23 publications

References 16 publications

Towards extracellular Ca2+ sensing by MRI: synthesis and calcium-dependent 1H and 17O relaxation studies of two novel bismacrocyclic Gd3+ complexes

Towards extracellular Ca2+ sensing by MRI: synthesis and calcium-dependent 1H and 17O relaxation studies of two novel bismacrocyclic Gd3+ complexes

Gd(iii) complex of a monophosphinate-bis(phosphonate) DOTA analogue with a high relaxivity; Lanthanide(iii) complexes for imaging and radiotherapy of calcified tissues

Simple analytical approximation of the longitudinal electronic relaxation rate of Gd(iii) complexes in solutions

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