MRI and fluorescence studies of Saccharomyces cerevisiae loaded with a bimodal Fe(III) T1 contrast agent

Patel, Akanksha; Asik, Didar; Spernyak, Joseph A.; Cullen, Paul J.; Morrow, Janet R.

doi:10.1016/j.jinorgbio.2019.110832

Cited by 16 publications

(37 citation statements)

References 48 publications

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“…In fact, Fe(L1) and Fe(L3) both have higher relaxivity than Fe(III) complexes with a single innersphere water molecule, such as Fe(EDTA) (1.34 mM -1 s -1 at 4.7 T). [21] As discussed above, Fe(L1) and Fe(L3) have one deprotonated alcohol ligand or hydroxide at neutral pH. Given the higher r1 proton relaxivity and apparent lack of exchangeable innersphere water, a hydroxide ligand may be responsible for strong second sphere water interactions, similar to a reported Fe(III) porphyrin with fluoride and no bound water ligands.…”

Section: Compoundmentioning

confidence: 79%

“…The complexes with triazole pendent produce the lowest relaxivity. Both triazole complexes have r1 relaxivities that are similar to Fe(III) complexes that have no bound water including Fe(DTPA) at 0.57 mM -1 s -1 at 4.7 T. [21] It is interesting that Fe(L1) and Fe(L3) have r1 relaxivities that are several times higher than those of Fe(L2) or Fe(L4). In fact, Fe(L1) and Fe(L3) both have higher relaxivity than Fe(III) complexes with a single innersphere water molecule, such as Fe(EDTA) (1.34 mM -1 s -1 at 4.7 T).…”

Section: Compoundmentioning

confidence: 94%

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A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents

et al. 2019

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Section: Compoundmentioning

confidence: 79%

Section: Compoundmentioning

confidence: 94%

A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents

et al. 2019

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“…The higher relaxivity is promoted by strong second-sphere water interactions that are mediated by the water ligand in conjunction with the hydroxypropyl pendant groups. Notably, both Fe(L1)(OH 2 ) and Fe(L3)(OH 2 ) have higher relaxivity than Fe(EDTA) (1.4 mM −1 •s −1 at 4.7 T) which has an exchangeable water ligand [18]. Similarly, the relaxivity of Fe(L2) is higher than that of Fe(DTPA) at 0.51 mM −1 •s −1 , with both complexes lacking a bound exchangeable water [18].…”

Section: Discussionmentioning

confidence: 99%

“…Notably, both Fe(L1)(OH 2 ) and Fe(L3)(OH 2 ) have higher relaxivity than Fe(EDTA) (1.4 mM −1 •s −1 at 4.7 T) which has an exchangeable water ligand [18]. Similarly, the relaxivity of Fe(L2) is higher than that of Fe(DTPA) at 0.51 mM −1 •s −1 , with both complexes lacking a bound exchangeable water [18]. These comparisons suggest that the hydroxy groups of the macrocyclic complexes, as well as the static water ligand, serve to enhance second-sphere water interactions.…”

Section: Discussionmentioning

confidence: 99%

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Modulating the Properties of Fe(III) Macrocyclic MRI Contrast Agents by Appending Sulfonate or Hydroxyl Groups

et al. 2020

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Complexes of Fe(III) that contain a triazacyclononane (TACN) macrocycle, two pendant hydroxyl groups, and a third ancillary pendant show promise as MRI contrast agents. The ancillary group plays an important role in tuning the solution relaxivity of the Fe(III) complex and leads to large changes in MRI contrast enhancement in mice. Two new Fe(III) complexes, one with a third coordinating hydroxypropyl pendant, Fe(L2), and one with an anionic non-coordinating sulfonate group, Fe(L1)(OH2), are compared. Both complexes have a deprotonated hydroxyl group at neutral pH and electrode potentials representative of a stabilized trivalent iron center. The r1 relaxivity of the Fe(L1)(OH2) complex is double that of the saturated complex, Fe(L2), at 4.7 T, 37 °C in buffered solutions. However, variable-temperature 17O-NMR experiments show that the inner-sphere water of Fe(L1)(OH2) does not exchange rapidly with bulk water under these conditions. The pendant sulfonate group in Fe(L1)(OH2) confers high solubility to the complex in comparison to Fe(L2) or previously studied analogues with benzyl groups. Dynamic MRI studies of the two complexes showed major differences in their pharmacokinetics clearance rates compared to an analogue containing a benzyl ancillary group. Rapid blood clearance and poor binding to serum albumin identify Fe(L1)(OH2) for development as an extracellular fluid contrast agent.

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Transition Metal ParaCEST, LipoCEST, and CellCEST Agents as MRI Probes

Morrow

Chowdhury

Abozeid

et al. 2020

Encyclopedia of Inorganic and Bioinorganic Chemistry

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First‐row transition metal (TM) complexes are of interest as members of a relatively new class of coordination complexes that produce MRI contrast through CEST (chemical‐exchange saturation transfer). CEST reduces the intensity of the water protons upon exchange of a selectively magnetically saturated proton with the water proton pool. Paramagnetic TM complexes produce large paramagnetically shifted protons, which facilitates CEST signal intensity by avoiding tissue background signal (paraCEST agents) and also allowing for faster proton‐exchange rates. TM paraCEST agents have certain advantages over lanthanide paraCEST agents including the possibility of tuning oxidation and spin states to allow for the development of responsive agents. Moreover, the covalent bonding character of the TM ions bestows large through‐bond contributions to the hyperfine shifts of protons, which is beneficial for paraCEST agents. New applications include the development of TM water proton shift reagents (SRs) for improvement of sensitivity through incorporation into supramolecular assemblies. Liposomes with encapsulated and amphiphilic SRs produce lipoCEST, and cells loaded with SRs produce cellCEST. This article summarizes TM paraCEST agents and SRs and highlights new research directions.

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MRI and fluorescence studies of Saccharomyces cerevisiae loaded with a bimodal Fe(III) T1 contrast agent

Cited by 16 publications

References 48 publications

A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents

A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents

Modulating the Properties of Fe(III) Macrocyclic MRI Contrast Agents by Appending Sulfonate or Hydroxyl Groups

Transition Metal ParaCEST, LipoCEST, and CellCEST Agents as MRI Probes

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MRI and fluorescence studies of Saccharomyces cerevisiae loaded with a bimodal Fe(III) T1 contrast agent

Cited by 16 publications

References 48 publications

A Class of FeIII Macrocyclic Complexes with Alcohol Donor Groups as Effective T1 MRI Contrast Agents

A Class of FeIII Macrocyclic Complexes with Alcohol Donor Groups as Effective T1 MRI Contrast Agents

Modulating the Properties of Fe(III) Macrocyclic MRI Contrast Agents by Appending Sulfonate or Hydroxyl Groups

Transition Metal ParaCEST, LipoCEST, and CellCEST Agents as MRI Probes

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Product

Resources

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A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents

A Class of Fe^III Macrocyclic Complexes with Alcohol Donor Groups as Effective T₁ MRI Contrast Agents