How to determine free Gd and free ligand in solution of Gd chelates. A technical note

Barge, Alessandro; Cravotto, Giancarlo; Gianolio, Eliana; Fedeli, Franco

doi:10.1002/cmmi.110

Cited by 256 publications

(262 citation statements)

References 10 publications

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“…The absence of free Dy 3+ and Tb 3+ ions in solution was verified by the xylenol orange test. 47,48 Final concentrations were checked by the Evans method.…”

Section: A Sample Preparationmentioning

confidence: 99%

Influence of Dy3+ and Tb3+ doping on 13C dynamic nuclear polarization

Niedbalski

Parish

Kiswandhi

et al. 2017

The Journal of Chemical Physics

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Dynamic nuclear polarization (DNP) is a technique that uses a microwave-driven transfer of high spin alignment from electrons to nuclear spins. This is most effective at low temperature and high magnetic field, and with the invention of the dissolution method, the amplified nuclear magnetic resonance (NMR) signals in the frozen state in DNP can be harnessed in the liquid-state at physiologically acceptable temperature for in vitro and in vivo metabolic studies. A current optimization practice in dissolution DNP is to dope the sample with trace amounts of lanthanides such as Gd 3+ or Ho 3+ , which further improves the polarization. While Gd 3+ and Ho 3+ have been optimized for use in dissolution DNP, other lanthanides have not been exhaustively studied for use in 13 C DNP applications. In this work, two additional lanthanides with relatively high magnetic moments, Dy 3+ and Tb 3+ , were extensively optimized and tested as doping additives for 13 C DNP at 3.35 T and 1.2 K. We have found that both of these lanthanides are also beneficial additives, to a varying degree, for 13 C DNP. The optimal concentrations of Dy 3+ (1.5 mM) and Tb 3+ (0.25 mM) for 13 C DNP were found to be less than that of Gd 3+ (2 mM). W-band electron paramagnetic resonance shows that these enhancements due to Dy 3+ and Tb 3+ doping are accompanied by shortening of electron T 1 of trityl OX063 free radical. Furthermore, when dissolution was employed, Tb 3+ -doped samples were found to have similar liquid-state 13 C NMR signal enhancements compared to samples doped with Gd 3+ , and both Tb 3+ and Dy 3+ had a negligible liquid-state nuclear T 1 shortening effect which contrasts with the significant reduction in T 1 when using Gd 3+ . Our results show that Dy 3+ doping and Tb 3+ doping have a beneficial impact on 13 C DNP both in the solid and liquid states, and that Tb 3+ in particular could be used as a potential alternative to Gd 3+ in 13 C dissolution DNP experiments. Published by AIP Publishing.

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“…The absence of free Dy 3+ and Tb 3+ ions in solution was verified by the xylenol orange test. 47,48 Final concentrations were checked by the Evans method.…”

Section: A Sample Preparationmentioning

confidence: 99%

Influence of Dy3+ and Tb3+ doping on 13C dynamic nuclear polarization

Niedbalski

Parish

Kiswandhi

et al. 2017

The Journal of Chemical Physics

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“…was filtered, and the solvent was evaporated under vacuum. Xylenol or arsenazo tests confirmed the absence of free Gd [18]. The product was treated with 50 ml of dist.…”

Section: Experimental Partmentioning

confidence: 98%

Noncovalent Binding of Some New Lipophilic Gadolinium DTPA Complexes to Human Serum Albumin. A Structure–Affinity Relationship

Laurent

Elst

Henrotte

et al. 2010

Chemistry & Biodiversity

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Four Gadolinium⋅DTPA complexes bearing long lipophilic alkyl chains were synthesized: two bis[amide] and two 4-substituted derivatives. In two of them (one bis[amide] and one 4-substituted), the alkyl chain ends with a carboxylate function. Their relaxometric properties in H₂O show the self aggregation of Gd⋅DTPA-BdodecylAmide, the better stability of the 4-substituted derivatives vs. Zn transmetallation, and the very good stability of Gd⋅(4-(carboxyundecylisothiourea-Bz)DTPA). Amongst the four compounds, only Gd⋅(4-(carboxyundecylisothiourea-Bz)DTPA) shows a strong interaction with human serum albumin (HSA) as demonstrated by proton relaxometry and ESI mass spectrometry. These data highlight the importance of the negative charge on the alkyl chain in the context of the interaction of Gd⋅(4-substituted DTPA) derivatives with HSA.

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“…The amount of residual free Gd 3 + ion was assessed by the orange xylenol UV method. [24] GdL1 and Gd 3 L2 were found to contain less than 0.3 % (mol/mol) of residual free Gd …”

Section: Synthesis Of Gd Complexesmentioning

confidence: 98%

Target Visualization by MRI Using the Avidin/Biotin Amplification Route: Synthesis and Testing of a Biotin–Gd‐DOTA Monoamide Trimer

Tei

Barge

Crich

et al. 2010

Chemistry A European J

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To design efficient targeting strategies in magnetic resonance (MR) molecular imaging applications, the formation of supramolecular adducts between (strept)avidin ((S)Av) and tribiotinylated Gd-DOTA-monoamide complexes (DOTA=1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) was explored. Two compounds based on the trivalent core of tris(2-aminoethyl)amine each containing three biotin molecules and one (L1) or three (L2) DOTA-monoamide (DOTAMA) ligands were synthesized. In these tribiotinylated derivatives the biotins are spaced far enough apart to allow the formation of the supramolecular adduct with the protein and to host the chelating units in between the (S)Av layers. Size exclusion HPLC analyses indicated complete formation of very high molecular weight polymers (>2 MDa) with (S)Av in solution. A (1)H NMR spectroscopy relaxometric study on the obtained polymeric adducts showed a marked increase of the relaxivity at 35-40 MHz as a consequence of the lengthening of the tumbling time due to the formation of Gd-chelates/(S)Av polymers. The most efficient Gd(3)L2/(S)Av polymeric system was used for a test in cell cultures. The target is represented by a neural cell adhesion molecule (NCAM), which is overexpressed in Kaposi's sarcoma cells and tumor endothelial cells (TEC) and that is efficiently recognized by a biotinylated tetrameric peptide (C3d-Bio). In vitro experiments showed that only cells incubated with both C3d-Bio and Gd(3)L2/SAv polymer were hyperintense with respect to the control. Relaxation rates of cell pellets incubated with Gd(3)L2/SAv alone were not significantly different from the untreated cells demonstrating the absence of a specific binding.

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How to determine free Gd and free ligand in solution of Gd chelates. A technical note

Cited by 256 publications

References 10 publications

Influence of Dy3+ and Tb3+ doping on 13C dynamic nuclear polarization

Influence of Dy3+ and Tb3+ doping on 13C dynamic nuclear polarization

Noncovalent Binding of Some New Lipophilic Gadolinium DTPA Complexes to Human Serum Albumin. A Structure–Affinity Relationship

Target Visualization by MRI Using the Avidin/Biotin Amplification Route: Synthesis and Testing of a Biotin–Gd‐DOTA Monoamide Trimer

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