Paramagnetic chemical exchange saturation transfer agents and their perspectives for application in magnetic resonance imaging

Rodríguez-Rodríguez, Aurora; Zaiß, Moritz; Esteban‐Gómez, David; Angelovski, Goran; Platas‐Iglesias, Carlos

doi:10.1080/0144235x.2020.1823167

Cited by 18 publications

(19 citation statements)

References 121 publications

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“…Importantly, the k ex values at 37 °C are in the optimal range of 1.5–2.5 kHz, which combined with the high number of the NMR equivalent and shifted protons (two groups, each with four protons) makes this platform very attractive for the further development of potent paraCEST probes. , Concurrently, the obtained exchange rates for [PrL 6 ] 3+ were in a range similar to that for [TbL 6 ] 3+ (Table S2), albeit exhibiting somewhat slower exchange rates. Nevertheless, the low paramagnetic shift of the CEST peaks limits the potential use of this complex in future paraCEST MRI studies.…”

Section: Results and Discussionmentioning

confidence: 68%

“…Because of such an advantageous prospective, complexes of both paramagnetic lanthanide and transition-metal ions were extensively investigated as potential paraCEST candidates. − In the particular case of lanthanide ions, most of the complexes investigated in this context were derivatives of cyclen because this type of chelator often forms very stable and inert complexes when functionalized with four pendant arms . However, azamacrocyclic platforms other than cyclen were also investigated as possible chelators to form inert complexes with affirmative CEST features.…”

Section: Introductionmentioning

confidence: 99%

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Lanthanide(III) Complexes Based on an 18-Membered Macrocycle Containing Acetamide Pendants. Structural Characterization and paraCEST Properties

et al. 2021

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We report a detailed investigation of the coordination properties of macrocyclic lanthanide complexes containing a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane scaffold functionalized with four acetamide pendant arms. The X-ray structures of the complexes with the large Ln3+ ions (La and Sm) display 12- and 10-coordinated metal ions, where the coordination sphere is fulfilled by the six N atoms of the macrocycle, the four O atoms of the acetamide pendants, and a bidentate nitrate anion in the La3+ complex. The analogous Yb3+ complex presents, however, a 9-coordinated metal ion because one of the acetamide pendant arms remains uncoordinated. 1H NMR studies indicate that the 10-coordinated form is present in solution throughout the lanthanide series from La to Tb, while the smaller lanthanides form 9-coordinated species. 1H and 89Y NMR studies confirm the presence of this structural change because the two species are present in solution. Analysis of the 1H chemical shifts observed for the Tb3+ complex confirms its D 2 symmetry in aqueous solution and evidences a highly rhombic magnetic susceptibility tensor. The acetamide resonances of the Pr3+ and Tb3+ complexes provided sizable paraCEST effects, as demonstrated by the corresponding Z-spectra recorded at different temperatures and studies on tube phantoms recorded at 22 °C.

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Section: Results and Discussionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Lanthanide(III) Complexes Based on an 18-Membered Macrocycle Containing Acetamide Pendants. Structural Characterization and paraCEST Properties

et al. 2021

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“…These simulations only take into account direct saturation with a moderate T 2w = T 2s = 0.1 s and not semi‐solid MT. Inclusion of MT effects may further reduce contrast, as has been described previously 183 . In fact, this dependence on microenvironment is a positive feature, as changes in environmental pH result in significant differences in contrast for any CEST pH sensor such as iopamidol or I45DC‐diGlu, enabling the production of pH maps.…”

Section: Discussionmentioning

confidence: 89%

“…Inclusion of MT effects may further reduce contrast, as has been described previously. 183 In fact, this dependence on microenvironment is a positive feature, as changes in environmental pH result in significant differences in contrast for any CEST pH sensor such as iopamidol or I45DC-diGlu, enabling the production of pH maps. Other important factors include pharmacokinetics of the agent and toxicity of the compounds.…”

Section: Discussionmentioning

confidence: 99%

A snapshot of the vast array of diamagnetic CEST MRI contrast agents

et al. 2022

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Since the inception of CEST MRI in the 1990s, a number of compounds have been identified as suitable for generating contrast, including paramagnetic lanthanide complexes, hyperpolarized atom cages and, most interesting, diamagnetic compounds. In the past two decades, there has been a major emphasis in this field on the identification and application of diamagnetic compounds that have suitable biosafety profiles for usage in medical applications. Even in the past five years there has been a tremendous growth in their numbers, with more and more emphasis being placed on finding those that can be ultimately used for patient studies on clinical 3 T scanners. At this point, a number of endogenous compounds present in tissue have been identified, and also natural and synthetic organic compounds that can be administered to highlight pathology via CEST imaging. Here we will provide a very extensive snapshot of the types of diamagnetic compound that can generate CEST MRI contrast, together with guidance on their utility on typical preclinical and clinical scanners and a review of the applications that might benefit the most from this new technology.

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“…The general requirement for successful CEST is that the frequency difference between the two pools of protons (Δω) is greater than the corresponding exchange rate (kex) [6]. Moreover, the paramagnetic lanthanide(III) ions, such as Eu(III), Tb(III) or Yb(III), are known to induce chemical shifts (and hence Δω), which makes them perfect candidates for paramagnetic CEST (paraCEST) CAs [7][8][9]. As a general rule, the CEST effect is induced either by the exchangeable proton of the ligand or by the water molecule coordinated to Ln(III).…”

Section: Introductionmentioning

confidence: 99%

Macrocyclic Chelates Bridged by a Diaza-Crown Ether: Towards Multinuclear Bimodal Molecular Imaging Probes

Wang

Angelovski

2020

Molecules

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Bridged polymacrocyclic ligands featured by structurally different cages offer the possibility of coordinating multiple trivalent lanthanide ions, giving rise to the exploitation of their different physicochemical properties, e.g., multimodal detection for molecular imaging purposes. Intrigued by the complementary properties of optical and MR-based image capturing modalities, we report the synthesis and characterization of the polymetallic Ln(III)-based chelate comprised of two DOTA-amide-based ligands (DOTA—1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) bridged via 1,10-diaza-18-crown-6 (DA18C6) motif. The DOTA-amide moieties and the DA18C6 were used to chelate two Eu(III) ions and one Tb(III) ion, respectively, resulting in a multinuclear heterometallic complex Eu2LTb. The bimetallic complex without Tb(III), Eu2L, displayed a strong paramagnetic chemical exchange saturation transfer (paraCEST) effect. Notably, the luminescence spectra of Eu2LTb featured mixed emission including the characteristic bands of Eu(III) and Tb(III). The advantageous features of the complex Eu2LTb opens new possibilities for the future design of bimodal probes and their potential applicability in CEST MR and optical imaging.

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Paramagnetic chemical exchange saturation transfer agents and their perspectives for application in magnetic resonance imaging

Cited by 18 publications

References 121 publications

Lanthanide(III) Complexes Based on an 18-Membered Macrocycle Containing Acetamide Pendants. Structural Characterization and paraCEST Properties

Lanthanide(III) Complexes Based on an 18-Membered Macrocycle Containing Acetamide Pendants. Structural Characterization and paraCEST Properties

A snapshot of the vast array of diamagnetic CEST MRI contrast agents

Macrocyclic Chelates Bridged by a Diaza-Crown Ether: Towards Multinuclear Bimodal Molecular Imaging Probes

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