1
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Baek AR, Kim HK, Kim S, Yang JU, Kang MK, Lee JJ, Sung B, Lee H, Kim M, Cho AE, Park JA, Chang Y. Effect of Structural Fine-Tuning on Chelate Stability and Liver Uptake of Anionic MRI Contrast Agents. J Med Chem 2022; 65:6313-6324. [PMID: 35418226 DOI: 10.1021/acs.jmedchem.2c00291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The purpose of this study is to assess the physicochemical properties and MRI diagnostic efficacy of two newly synthesized 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-type Gd chelates, Gd-SucL and Gd-GluL, with an asymmetric α-substituted pendant arm as potential hepatocyte-specific magnetic resonance imaging contrast agents (MRI CAs). Our findings show that fine conformational changes in the chelating arm affect the in vivo pharmacokinetic behavior of the MRI CA, and that a six-membered chelating substituent of Gd-SucL is more advantageous in this system to avoid unwanted interactions with endogenous species. Gd-SucL exhibited a general DOTA-like chelate stability trend, indicating that all chelating arms retain coordination bonding. Finally, the in vivo diagnostic efficacy of highly stable Gd-SucL as a potential hepatocyte-specific MRI CA was evaluated using T1-weighted MR imaging on an orthotopic hepatocarcinoma model.
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Affiliation(s)
- Ah Rum Baek
- Institute of Biomedical Engineering Research, Kyungpook National University, 41405 Daegu, Korea
| | - Hee-Kyung Kim
- Preclinical Research Center, Daegu-Gyeongbuk Medical Innovation Foundation, 41061 Daegu, Korea
| | - Soyeon Kim
- Division of RI-Convergence Research, Korea Institute of Radiological and Medical Sciences, 139-706 Seoul, Korea
| | - Ji-Ung Yang
- Division of RI-Convergence Research, Korea Institute of Radiological and Medical Sciences, 139-706 Seoul, Korea
| | - Min-Kyoung Kang
- Laboratory Animal Center, KBIO Osong Medical Innovation Foundation, 28160 Osong, Korea
| | - Jae Jun Lee
- Laboratory Animal Center, KBIO Osong Medical Innovation Foundation, 28160 Osong, Korea
| | - Bokyung Sung
- Department of Medical & Biological Engineering, Kyungpook National University, 41944 Daegu, Korea
| | - Hyeji Lee
- Department of Biomedical Science, Kyungpook National University, 419944 Daegu, Korea
| | - Minsup Kim
- InCerebro Drug Discovery Institute, 01811 Seoul, Korea
| | - Art E Cho
- InCerebro Drug Discovery Institute, 01811 Seoul, Korea
| | - Ji-Ae Park
- Division of RI-Convergence Research, Korea Institute of Radiological and Medical Sciences, 139-706 Seoul, Korea
| | - Yongmin Chang
- Institute of Biomedical Engineering Research, Kyungpook National University, 41405 Daegu, Korea.,Department of Medical & Biological Engineering, Kyungpook National University, 41944 Daegu, Korea.,Department of Biomedical Science, Kyungpook National University, 419944 Daegu, Korea.,Department of Radiology, Kyungpook National University Hospital, 41944 Daegu, Korea.,Department of Molecular Medicine, School of Medicine, Kyungpook National University, 41944 Daegu, Korea
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2
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Bruzzese PC, Salvadori E, Jäger S, Hartmann M, Civalleri B, Pöppl A, Chiesa M. 17O-EPR determination of the structure and dynamics of copper single-metal sites in zeolites. Nat Commun 2021; 12:4638. [PMID: 34330914 PMCID: PMC8324863 DOI: 10.1038/s41467-021-24935-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/07/2021] [Indexed: 02/07/2023] Open
Abstract
The bonding of copper ions to lattice oxygens dictates the activity and selectivity of copper exchanged zeolites. By 17O isotopic labelling of the zeolite framework, in conjunction with advanced EPR methodologies and DFT modelling, we determine the local structure of single site CuII species, we quantify the covalency of the metal-framework bond and we assess how this scenario is modified by the presence of solvating H216O or H217O molecules. This enables to follow the migration of CuII species as a function of hydration conditions, providing evidence for a reversible transfer pathway within the zeolite cage as a function of the water pressure. The results presented in this paper establish 17O EPR as a versatile tool for characterizing metal-oxide interactions in open-shell systems.
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Affiliation(s)
- Paolo Cleto Bruzzese
- grid.9647.c0000 0004 7669 9786Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany ,grid.7605.40000 0001 2336 6580Department of Chemistry and NIS Centre of Excellence, University of Turin, Torino, Italy
| | - Enrico Salvadori
- grid.7605.40000 0001 2336 6580Department of Chemistry and NIS Centre of Excellence, University of Turin, Torino, Italy
| | - Stefan Jäger
- Erlangen Center for Interface Research and Catalysis (ECRC), Erlangen, Germany
| | - Martin Hartmann
- Erlangen Center for Interface Research and Catalysis (ECRC), Erlangen, Germany
| | - Bartolomeo Civalleri
- grid.7605.40000 0001 2336 6580Department of Chemistry and NIS Centre of Excellence, University of Turin, Torino, Italy
| | - Andreas Pöppl
- grid.9647.c0000 0004 7669 9786Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany
| | - Mario Chiesa
- grid.7605.40000 0001 2336 6580Department of Chemistry and NIS Centre of Excellence, University of Turin, Torino, Italy
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3
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Gompa TP, Greer SM, Rice NT, Jiang N, Telser J, Ozarowski A, Stein BW, La Pierre HS. High-Frequency and -Field Electron Paramagnetic Resonance Spectroscopic Analysis of Metal-Ligand Covalency in a 4f 7 Valence Series (Eu 2+, Gd 3+, and Tb 4+). Inorg Chem 2021; 60:9064-9073. [PMID: 34106710 DOI: 10.1021/acs.inorgchem.1c01062] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The recent isolation of molecular tetravalent lanthanide complexes has enabled renewed exploration of the effect of oxidation state on the single-ion properties of the lanthanide ions. Despite the isotropic nature of the 8S ground state in a tetravalent terbium complex, [Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4], preliminary X-band electron paramagnetic resonance (EPR) measurements on tetravalent terbium complexes show rich spectra with broad resonances. The complexity of these spectra highlights the limits of conventional X-band EPR for even qualitative determination of zero-field splitting (ZFS) in these complexes. Therefore, we report the synthesis and characterization of a novel valence series of 4f7 molecular complexes spanning three oxidation states (Eu2+, Gd3+, and Tb4+) featuring a weak-field imidophosphorane ligand system, and employ high-frequency and -field electron paramagnetic resonance (HFEPR) to obtain quantitative values for ZFS across this valence series. The series was designed to minimize deviation in the first coordination sphere from the pseudotetrahedral geometry in order to directly interrogate the role of metal identity and charge on the complexes' electronic structures. These HFEPR studies are supported by crystallographic analysis and quantum-chemical calculations to assess the relative covalent interactions in each member of this valence series and the effect of the oxidation state on the splitting of the ground state and first excited state.
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Affiliation(s)
| | - Samuel M Greer
- Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, United States
| | | | | | - Joshua Telser
- Department of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, Florida 32310, United States
| | - Benjamin W Stein
- Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, United States
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4
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Webber BC, Payne KM, Rust LN, Cassino C, Carniato F, McCormick T, Botta M, Woods M. Analysis of the Relaxometric Properties of Extremely Rapidly Exchanging Gd 3+ Chelates: Lessons from a Comparison of Four Isomeric Chelates. Inorg Chem 2020; 59:9037-9046. [PMID: 32536158 DOI: 10.1021/acs.inorgchem.0c00905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Relaxometric analyses and in particular the use of fast-field cycling techniques have become routine in the study of paramagnetic metal complexes. The field dependence of the solvent proton relaxation properties (nuclear magnetic relaxation dispersion, NMRD) can provide unparalleled insights into the chemistry of these complexes. However, analyzing NMRD data is a multiparametric problem, and some sets of variables are mutually compensatory. Specifically, when fitting NMRD profiles, the metal-proton distance and the rotational correlation time constant have a push-pull relationship in which a change to one causes a predictable compensation in the other. A relaxometric analysis of four isomeric chelates highlights the pitfalls that await when fitting the NMRD profiles of chelates for which dissociative water exchange is extremely rapid. In the absence of independently verified values for one of these parameters, NMRD profiles can be fitted to multiple parameter sets. This means that NMRD fitting can inadvertently be used to buttress a preconceived notion of how the complex should behave when a different parameter set may more accurately describe the actual behavior. These findings explain why the effect of very rapid dissociative exchange on the hydration state of Gd3+ has remained obscured until only recently.
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Affiliation(s)
- Benjamin C Webber
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, Oregon 97201, United States
| | - Katherine M Payne
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, Oregon 97201, United States
| | - Lauren N Rust
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, Oregon 97201, United States
| | - Claudio Cassino
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "Amedeo Avogadro″, Viale T. Michel 11, I-15121 Alessandria, Italy
| | - Fabio Carniato
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "Amedeo Avogadro″, Viale T. Michel 11, I-15121 Alessandria, Italy
| | - Theresa McCormick
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, Oregon 97201, United States
| | - Mauro Botta
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "Amedeo Avogadro″, Viale T. Michel 11, I-15121 Alessandria, Italy
| | - Mark Woods
- Department of Chemistry, Portland State University, 1719 SW 10th Avenue, Portland, Oregon 97201, United States.,Advanced Imaging Research Center, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
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5
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Wahsner J, Gale EM, Rodríguez-Rodríguez A, Caravan P. Chemistry of MRI Contrast Agents: Current Challenges and New Frontiers. Chem Rev 2019; 119:957-1057. [PMID: 30350585 PMCID: PMC6516866 DOI: 10.1021/acs.chemrev.8b00363] [Citation(s) in RCA: 832] [Impact Index Per Article: 166.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tens of millions of contrast-enhanced magnetic resonance imaging (MRI) exams are performed annually around the world. The contrast agents, which improve diagnostic accuracy, are almost exclusively small, hydrophilic gadolinium(III) based chelates. In recent years concerns have arisen surrounding the long-term safety of these compounds, and this has spurred research into alternatives. There has also been a push to develop new molecularly targeted contrast agents or agents that can sense pathological changes in the local environment. This comprehensive review describes the state of the art of clinically approved contrast agents, their mechanism of action, and factors influencing their safety. From there we describe different mechanisms of generating MR image contrast such as relaxation, chemical exchange saturation transfer, and direct detection and the types of molecules that are effective for these purposes. Next we describe efforts to make safer contrast agents either by increasing relaxivity, increasing resistance to metal ion release, or by moving to gadolinium(III)-free alternatives. Finally we survey approaches to make contrast agents more specific for pathology either by direct biochemical targeting or by the design of responsive or activatable contrast agents.
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Affiliation(s)
- Jessica Wahsner
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Eric M. Gale
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Aurora Rodríguez-Rodríguez
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Peter Caravan
- Athinoula A. Martinos Center for Biomedical Imaging and the Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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6
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Zhang B, Cheng L, Duan B, Tang W, Yuan Y, Ding Y, Hu A. Gadolinium complexes of diethylenetriamine-N-oxide pentaacetic acid-bisamide: a new class of highly stable MRI contrast agents with a hydration number of 3. Dalton Trans 2019; 48:1693-1699. [DOI: 10.1039/c8dt04478c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diethylenetriamine-N-oxide pentaacetic acid-bisamide-based Gd(iii) complexes with 3 coordinated water molecules have been synthesized to achieve high stability and over three times of the relaxivities of commercial MRI contrast agents.
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Affiliation(s)
- BeiBei Zhang
- Shanghai Key Laboratory of Advanced Polymeric Materials
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai
- China
| | - Likun Cheng
- Shanghai Key Laboratory of Advanced Polymeric Materials
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai
- China
| | - Bing Duan
- The State Key Laboratory of Bioreactor Engineering East China University of Science and Technology
- Shanghai
- China
| | - Weijun Tang
- Department of Radiology
- Huashan Hospital Affiliated to Fudan University
- Shanghai
- China
| | - Yuan Yuan
- The State Key Laboratory of Bioreactor Engineering East China University of Science and Technology
- Shanghai
- China
| | - Yun Ding
- Shanghai Key Laboratory of Advanced Polymeric Materials
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai
- China
| | - Aiguo Hu
- Shanghai Key Laboratory of Advanced Polymeric Materials
- School of Materials Science and Engineering
- East China University of Science and Technology
- Shanghai
- China
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7
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Collauto A, Mishra S, Litvinov A, Mchaourab HS, Goldfarb D. Direct Spectroscopic Detection of ATP Turnover Reveals Mechanistic Divergence of ABC Exporters. Structure 2017; 25:1264-1274.e3. [PMID: 28712805 DOI: 10.1016/j.str.2017.06.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/05/2017] [Accepted: 06/15/2017] [Indexed: 12/27/2022]
Abstract
We have applied high-field (W-band) pulse electron-nuclear double resonance (ENDOR) and electron-electron double resonance (ELDOR)-detected nuclear magnetic resonance (EDNMR) to characterize the coordination sphere of the Mn2+ co-factor in the nucleotide binding sites (NBSs) of ABC transporters. MsbA and BmrCD are two efflux transporters hypothesized to represent divergent catalytic mechanisms. Our results reveal distinct coordination of Mn2+ to ATP and transporter residues in the consensus and degenerate NBSs of BmrCD. In contrast, the coordination of Mn2+ at the two NBSs of MsbA is similar, which provides a mechanistic rationale for its higher rate constant of ATP hydrolysis relative to BmrCD. Direct detection of vanadate ion, trapped in a high-energy post-hydrolysis intermediate, further supports the notion of asymmetric hydrolysis by the two NBSs of BmrCD. The integrated spectroscopic approach presented here, which link energy input to conformational dynamics, can be applied to a variety of systems powered by ATP turnover.
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Affiliation(s)
- Alberto Collauto
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Smriti Mishra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Aleksei Litvinov
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
| | - Daniella Goldfarb
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
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Rashid HU, Martines MAU, Jorge J, de Moraes PM, Umar MN, Khan K, Rehman HU. Cyclen-based Gd 3+ complexes as MRI contrast agents: Relaxivity enhancement and ligand design. Bioorg Med Chem 2016; 24:5663-5684. [PMID: 27729196 DOI: 10.1016/j.bmc.2016.09.069] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/25/2016] [Accepted: 09/28/2016] [Indexed: 12/23/2022]
Abstract
Magnetic Resonance Imaging (MRI) is a noninvasive radiology technique used to examine the internal organs of human body. It is useful for the diagnosis of structural abnormalities in the body. Contrast agents are used to increase the sensitivity of this technique. 1,4,7,10-Tetraazacyclododecane (cyclen) is a macrocyclic tetraamine. Its derivatives act as useful ligands to produce stable complexes with Gd3+ ion. Such chelates are investigated as MRI contrast agents. Free Gd3+ ion is extremely toxic for in vivo use. Upon complexation with a cyclen-based ligand, it is trapped in the preformed central cavity of the ligand resulting in the formation of a highly stable Gd3+-chelate. Better kinetic and thermodynamic stability of cyclen-based MRI contrast agents decrease their potential toxicity for in vivo use. Consequently, such agents have proved to be safest for clinical applications. Relaxivity is the most important parameter used to measure the effectiveness of a contrast agent. A number of factors influence this parameter. This article elucidates detailed strategies to increase relaxivity of cyclen-based MRI contrast agents. 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) are two key ligands derived from cyclen. They also act as building blocks for the synthesis of novel ligands. A few important methodologies for the synthesis of DOTA and DO3A derivatives are described. Moreover, the coordination geometry of chelates formed by these ligands and their derivatives is discussed as well. Novel ligands can be developed by the appropriate derivatization of DOTA and DO3A. Gd3+-chelates of such ligands prove to be useful MRI contrast agents of enhanced relaxivity, greater stability, better clearance, lesser toxicity and higher water solubility.
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Affiliation(s)
- Haroon Ur Rashid
- Department of Chemistry, Sarhad University of Science and Information Technology, Peshawar, Khyber Pakhtunkhwa, Pakistan; Institute of Chemistry, Federal University of Mato Grosso do Sul, Campo Grande, MS, Brazil.
| | | | - Juliana Jorge
- Institute of Chemistry, Federal University of Mato Grosso do Sul, Campo Grande, MS, Brazil
| | - Paula Martin de Moraes
- Institute of Chemistry, Federal University of Mato Grosso do Sul, Campo Grande, MS, Brazil
| | - Muhammad Naveed Umar
- Department of Chemistry, University of Malakand, Chakdara, Lower Dir, Khyber Pakhtunkhwa, Pakistan
| | - Kamin Khan
- Department of Chemistry, Sarhad University of Science and Information Technology, Peshawar, Khyber Pakhtunkhwa, Pakistan
| | - Hanif Ur Rehman
- Department of Chemistry, Sarhad University of Science and Information Technology, Peshawar, Khyber Pakhtunkhwa, Pakistan
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9
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Collauto A, Feintuch A, Qi M, Godt A, Meade T, Goldfarb D. Gd(III) complexes as paramagnetic tags: Evaluation of the spin delocalization over the nuclei of the ligand. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 263:156-163. [PMID: 26802219 DOI: 10.1016/j.jmr.2015.12.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/28/2015] [Accepted: 12/30/2015] [Indexed: 05/15/2023]
Abstract
Complexes of the Gd(III) ion are currently being established as spin labels for distance determination in biomolecules by pulse dipolar spectroscopy. Because Gd(III) is an f ion, one expects electron spin density to be localized on the Gd(III) ion - an important feature for the mentioned application. Most of the complex ligands have nitrogens as Gd(III) coordinating atoms. Therefore, measurement of the (14)N hyperfine coupling gives access to information on the localization of the electron spin on the Gd(III) ion. We carried out W-band, 1D and 2D (14)N and (1)H ENDOR measurements on the Gd(III) complexes Gd-DOTA, Gd-538, Gd-595, and Gd-PyMTA that serve as spin labels for Gd-Gd distance measurements. The obtained (14)N spectra are particularly well resolved, revealing both the hyperfine and nuclear quadrupole splittings, which were assigned using 2D Mims ENDOR experiments. Additionally, the spectral contributions of the two different types of nitrogen atoms of Gd-PyMTA, the aliphatic N atom and the pyridine N atom, were distinguishable. The (14)N hyperfine interaction was found to have a very small isotropic hyperfine component of -0.25 to -0.37MHz. Furthermore, the anisotropic hyperfine interactions with the (14)N nuclei and with the non-exchangeable protons of the ligands are well described by the point-dipole approximation using distances derived from the crystal structures. We therefore conclude that the spin density is fully localized on the Gd(III) ion and that the spin density distribution over the nuclei of the ligands is rightfully ignored when analyzing distance measurements.
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Affiliation(s)
- A Collauto
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - A Feintuch
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - M Qi
- University Bielefeld, Faculty of Chemistry and Center for Molecular Materials, D-33615 Bielefeld, Germany
| | - A Godt
- University Bielefeld, Faculty of Chemistry and Center for Molecular Materials, D-33615 Bielefeld, Germany
| | - T Meade
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - D Goldfarb
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
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10
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Manukovsky N, Frydman V, Goldfarb D. Gd3+ Spin Labels Report the Conformation and Solvent Accessibility of Solution and Vesicle-Bound Melittin. J Phys Chem B 2015; 119:13732-41. [DOI: 10.1021/acs.jpcb.5b03523] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Nurit Manukovsky
- Departments of †Chemical Physics and ‡Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Veronica Frydman
- Departments of †Chemical Physics and ‡Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniella Goldfarb
- Departments of †Chemical Physics and ‡Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
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Abstract
This perspective outlines strategies towards the development of MR imaging probes that our lab has explored over the last 15 years. Namely, we discuss methods to enhance the signal generating capacity of MR probes and how to achieve tissue specificity through protein targeting or probe activation within the tissue microenvironment.
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Affiliation(s)
- Eszter Boros
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Eric M Gale
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Peter Caravan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
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12
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Boros E, Caravan. P. Probing the structure-relaxivity relationship of bis-hydrated Gd(DOTAla) derivatives. Inorg Chem 2015; 54:2403-10. [PMID: 25693053 PMCID: PMC4758459 DOI: 10.1021/ic503035f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two structural isomers of the heptadentate chelator DO3Ala were synthesized, with carboxymethyl groups at either the 1,4- or 1,7-positions of the cyclen macrocycle. To interrogate the relaxivity under different rotatational dynamics regimes, the pendant primary amine was coupled to ibuprofen to enable binding to serum albumin. These chelators 6a and 6b form bis(aqua) ternary complexes with Gd(III) or Tb(III) as estimated from relaxivity measurements or luminescence lifetime measurements in water. The relaxivity of [Gd(6a)(H2O)2] and [Gd(6b)(H2O)2] was measured in the presence and absence of coordinating anions prevalent in vivo such as phosphate, lactate, and bicarbonate and compared with data attained for the q = 2 complex [Gd(DO3A)(H2O)2]. We found that relaxivity was reduced through formation of ternary complexes with lactate and bicarbonate, albeit to a lesser degree then the relaxivity of Gd(DO3A). In the presence of 100-fold excess phosphate, relaxivity was slightly increased and typical for q = 2 complexes of this size (8.3 mM(-1) s(-1) and 9.5 mM(-1) s(-1), respectively, at 37 °C, 60 MHz). Relaxivity for the complexes in the presence of HSA corresponded well to relaxivity obtained for complexes with reduced access for inner-sphere water (13.5 and 12.7 mM(-1) s(-1) at 37 °C, 60 MHz). Mean water residency time at 37 °C was determined using temperature-dependent (17)O-T2 measurements at 11.7 T and calculated to be (310)τM = 23 ± 1 ns for both structural isomers. Kinetic inertness under forcing conditions (pH 3, competing DTPA ligand) was found to be comparable to [Gd(DO3A)(H2O)]. Overall, we found that the replacement of one of the acetate arms of DO3A with an amino-propionate arm does not significantly alter the relaxometric and kinetic inertness properties of the corresponding Gd complexes; however, it does provide access to easily functionalizable q = 2 derivatives.
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Affiliation(s)
- Eszter Boros
- The Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 149 Thirteenth Street, Suite 2301, Charlestown, Massachusetts 02129, United States
| | - Peter Caravan.
- The Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 149 Thirteenth Street, Suite 2301, Charlestown, Massachusetts 02129, United States
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13
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Lee T, Bang D, Park Y, Kim SH, Choi J, Park J, Kim D, Kim E, Suh JS, Huh YM, Haam S. Gadolinium-enriched polyaniline particles (GPAPs) for simultaneous diagnostic imaging and localized photothermal therapy of epithelial cancer. Adv Healthc Mater 2014; 3:1408-14. [PMID: 24550214 DOI: 10.1002/adhm.201300636] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/01/2014] [Indexed: 11/08/2022]
Abstract
By loading Gd(III) inside NIR-absorbing polyaniline nanostructures, a novel diagnostic and photothermal agent with enhanced MR sensitivity, targeting ability, and photothermal ability to treat epithelial cancer is developed.
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Affiliation(s)
- Taeksu Lee
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
| | - Doyeon Bang
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
- Active Polymer Center for Pattern Integration (APCPI), Yonsei University; Seoul 120-749 Republic of Korea
| | - Yeonji Park
- Department of Radiology; Yonsei University; Seoul 120-752 Republic of Korea
| | - Sun Hee Kim
- Korea Basic Science Institute (KBSI); Daejeon Republic of Korea
| | - Jihye Choi
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
| | - Joseph Park
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
| | - Donghun Kim
- Korea Basic Science Institute (KBSI); Daejeon Republic of Korea
| | - Eunkyoung Kim
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
- Active Polymer Center for Pattern Integration (APCPI), Yonsei University; Seoul 120-749 Republic of Korea
| | - Jin-Suck Suh
- Department of Radiology; Yonsei University; Seoul 120-752 Republic of Korea
| | - Yong-Min Huh
- Department of Radiology; Yonsei University; Seoul 120-752 Republic of Korea
| | - Seungjoo Haam
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 120-749 Republic of Korea
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14
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Un S. Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions. Inorg Chem 2013; 52:3803-13. [PMID: 23510244 DOI: 10.1021/ic302415s] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in Deinococcus radiodurans are ligated to two histidines (Tabares, L. C.; Un, S. J. Biol. Chem 2013, in press).
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Affiliation(s)
- Sun Un
- Service de Bioénergétique, Biologie Structurale et Mécanismes (CNRS/UMR-8221), Institut de Biologie et de Technologies de Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France.
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15
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Astashkin AV, Nesmelov YE. Mn(2+)-nucleotide coordination at the myosin active site as detected by pulsed electron paramagnetic resonance. J Phys Chem B 2012; 116:13655-62. [PMID: 23121488 DOI: 10.1021/jp308423x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulsed electron paramagnetic resonance at the microwave K(a) band (~30 GHz) was used to study the coordination of adenosine nucleotides to Mn(2+) at the active site of myosin ATPase and in solution. We have found that the electron spin echo (ESE) field sweep, electron-nuclear double resonance (ENDOR) and ESE envelope modulation (ESEEM) techniques are not sufficiently specific for reliable differentiation between the solvated and myosin-bound Mn·nucleotide complexes. Therefore, to directly detect binding of the Mn·nucleotide to myosin, we used nonhydrolizable nucleotide analogs, site-directed spin labeling, and pulsed electron-electron double resonance to detect spin probe-manganese dipolar interaction. We found that under substoichiometric conditions, both Mn·AMPPNP and Mn·ADP·AlF(4) form a complex with myosin, and Mn·ADP does not form such a complex. This correlates well with the biological dissociation of Mg·ADP from myosin after the hydrolysis of ATP. The analysis of (31)P ENDOR spectra reveals that in Mn·AMPPNP, Mn·ATP, and Mn·ADP at myosin or in solution, the nucleotide is coordinated to Mn(2+) by two phosphate groups, whereas in Mn·ADP·AlF(4), only one phosphate group is coordinated. The observation of two phosphates and one nitrogen in the coordination sphere of Mn·ADP in solution by ESEEM spectroscopy suggests that a significant population of Mn ions is coordinated by two ADP molecules, one of which is coordinated by phosphates, and the other one, by a nitrogen atom. The developed approach will be generally useful for monitoring the metal-protein binding when such binding does not provide reliable spectroscopic signatures.
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Affiliation(s)
- Andrei V Astashkin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
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Kaminker I, Sushenko A, Potapov A, Daube S, Akabayov B, Sagi I, Goldfarb D. Probing conformational variations at the ATPase site of the RNA helicase DbpA by high-field electron-nuclear double resonance spectroscopy. J Am Chem Soc 2011; 133:15514-23. [PMID: 21819147 DOI: 10.1021/ja204291d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The RNA helicase DbpA promotes RNA remodeling coupled to ATP hydrolysis. It is unique because of its specificity to hairpin 92 of 23S rRNA (HP92). Although DbpA kinetic pathways leading to ATP hydrolysis and RNA unwinding have been recently elucidated, the molecular (atomic) basis for the coupling of ATP hydrolysis to RNA remodeling remains unclear. This is, in part, due to the lack of detailed structural information on the ATPase site in the presence and absence of RNA in solution. We used high-field pulse ENDOR (electron-nuclear double resonance) spectroscopy to detect and analyze fine conformational changes in the protein's ATPase site in solution. Specifically, we substituted the essential Mg(2+) cofactor in the ATPase active site for paramagnetic Mn(2+) and determined its close environment with different nucleotides (ADP, ATP, and the ATP analogues ATPγS and AMPPnP) in complex with single- and double-stranded RNA. We monitored the Mn(2+) interactions with the nucleotide phosphates through the (31)P hyperfine couplings and the coordination by protein residues through (13)C hyperfine coupling from (13)C-enriched DbpA. We observed that the nucleotide binding site of DbpA adopts different conformational states upon binding of different nucleotides. The ENDOR spectra revealed a clear distinction between hydrolyzable and nonhydrolyzable nucleotides prior to RNA binding. Furthermore, both the (13)C and the (31)P ENDOR spectra were found to be highly sensitive to changes in the local environment of the Mn(2+) ion induced by the hydrolysis. More specifically, ATPγS was efficiently hydrolyzed upon binding of RNA, similar to ATP. Importantly, the Mn(2+) cofactor remains bound to a single protein side chain and to one or two nucleotide phosphates in all complexes, whereas the remaining metal coordination positions are occupied by water. The conformational changes in the protein's ATPase active site associated with the different DbpA states occur in remote coordination shells of the Mn(2+) ion. Finally, a competitive Mn(2+) binding site was found for single-stranded RNA construct.
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Affiliation(s)
- Ilia Kaminker
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Jacques V, Dumas S, Sun WC, Troughton JS, Greenfield MT, Caravan P. High-relaxivity magnetic resonance imaging contrast agents. Part 2. Optimization of inner- and second-sphere relaxivity. Invest Radiol 2011; 45:613-24. [PMID: 20808234 DOI: 10.1097/rli.0b013e3181ee6a49] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES The observed relaxivity of gadolinium-based contrast agents has contributions from the water molecule(s) that bind directly to the gadolinium ion (inner-sphere water), long-lived water molecules and exchangeable protons that make up the second-sphere of coordination, and water molecules that diffuse near the contrast agent (outer-sphere). Inner- and second-sphere relaxivity can both be increased by optimization of the lifetimes of the water molecules and protons in these coordination spheres, the rotational motion of the complex, and the electronic relaxation of the gadolinium ion. We sought to identify new high-relaxivity contrast agents by systematically varying the donor atoms that bind directly to gadolinium to increase inner-sphere relaxivity and concurrently including substituents that influence the second-sphere relaxivity. METHODS Twenty gadolinium-1,4,7,10-tetraazacyclo-dodecane-N,N',N″,N'″-tetraacetato derivatives were prepared and their relaxivity determined in presence and absence of human serum albumin as a function of temperature and magnetic field. Data was analyzed to extract the underlying molecular parameters influencing relaxivity. Each compound had a common albumin-binding group and an inner-sphere donor set comprising the 4 tertiary amine N atoms from cyclen, an α-substituted acetate oxygen atom, 2 amide oxygen atoms, an inner-sphere water oxygen atom, and a variable donor group. Each amide nitrogen was substituted with different groups to promote hydrogen bonding with second-sphere water molecules. RESULTS Relativities at 0.47 and 1.4 T, 37°C, in serum albumin ranged from 16.0 to 58.1 mM(-1)s(-1) and from 12.3 to 34.8 mM(-1)s(-1), respectively. The reduction of inner-sphere water exchange typical of amide donor groups could be offset by incorporating a phosphonate or phenolate oxygen atom donor in the first coordination sphere, resulting in higher relaxivity. Amide nitrogen substitution with pendant phosphonate or carboxylate groups increased relaxivity by as much as 88% compared with the N-methyl amide analog. Second-sphere relaxivity contributed as much as 24 and 14 mM(-1)s(-1) at 0.47 and 1.4 T, respectively. CONCLUSIONS Water/proton exchange dynamics in the inner- and second-coordination sphere can be predictably tuned by choice of donor atoms and second-sphere substituents, resulting in high-relaxivity agents.
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High relaxivity magnetic resonance imaging contrast agents. Part 1. Impact of single donor atom substitution on relaxivity of serum albumin-bound gadolinium complexes. Invest Radiol 2011; 45:600-12. [PMID: 20808235 DOI: 10.1097/rli.0b013e3181ee5a9e] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES The donor atoms that bind to gadolinium in contrast agents influence inner-sphere water exchange and electronic relaxation, both of which determine observed relaxivity. The effect of these molecular parameters on relaxivity is greatest when the contrast agent is protein bound. We sought to determine an optimal donor atom set to yield high relaxivity compounds. METHODS A total of 38 gadolinium-1,4,7,10-tetraazacyclo-dodecane-N,N',N'',N'''-tetraacetato derivatives were prepared and relaxivity was determined in the presence and absence of human serum albumin as a function of temperature and magnetic field. Each compound had a common albumin-binding group and differed only by substitution of different donor groups at one of the macrocycle nitrogens. Oxygen-17 isotope relaxometry at 7.05 T was performed to estimate water exchange rates. RESULTS Changing a single donor atom resulted in changes in water exchange rates ranging across 3 orders of magnitude. Donor groups increased water exchange rate in the order: phosphonate ∼ phenolate > α-substituted acetate > acetate > hydroxamate ∼ sulfonamide > amide ∼ pyridyl ∼ imidazole. Relaxivites at 0.47 and 1.4 T, 37°C, ranged from 12.3 to 55.6 mM(-1)s(-1) and from 8.3 to 32.6 mM(-1)s(-1) respectively. Optimal relaxivities were observed when the donor group was an α-substituted acetate. Electronic relaxation was slowest for the acetate derivatives as well. CONCLUSIONS Water exchange dynamics and relaxivity can be predictably tuned by choice of donor atoms.
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Potapov A, Yagi H, Huber T, Jergic S, Dixon NE, Otting G, Goldfarb D. Nanometer-Scale Distance Measurements in Proteins Using Gd3+ Spin Labeling. J Am Chem Soc 2010; 132:9040-8. [DOI: 10.1021/ja1015662] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alexey Potapov
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Hiromasa Yagi
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Thomas Huber
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Slobodan Jergic
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Nicholas E. Dixon
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Gottfried Otting
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
| | - Daniella Goldfarb
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel, Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia, and School of Chemistry, University of Wollongong, NSW 2522, Australia
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20
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Caravan P. Protein-targeted gadolinium-based magnetic resonance imaging (MRI) contrast agents: design and mechanism of action. Acc Chem Res 2009; 42:851-62. [PMID: 19222207 DOI: 10.1021/ar800220p] [Citation(s) in RCA: 288] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Magnetic resonance imaging (MRI) is a powerful medical diagnostic technique: it can penetrate deep into tissue, provide excellent soft tissue contrast with sub-millimeter resolution, and does not employ ionizing radiation. Targeted contrast agents provide an additional layer of molecular specificity to the wealth of anatomical and functional information already attainable by MRI. However, the major challenge for molecular MR imaging is sensitivity: micromolar concentrations of Gd(III) are required to cause a detectable signal change, which makes detecting proteins by MRI a challenge. Protein-targeted MRI contrast agents are bifunctional molecules comprising a protein-targeting moiety and typically one or more gadolinium chelates for detection by MRI. The ability of the contrast agent to enhance the MR image is termed relaxivity, and it depends upon many molecular factors, including protein binding itself. As in other imaging modalities, protein binding provides the pharmacokinetic effect of concentrating the agent at the region of interest. Unique to MRI, protein binding provides the pharmacodynamic effect of increasing the relaxivity of the contrast agent, thereby increasing the MR signal. In designing new agents, optimization of both the targeting function and the relaxivity is critical. In this Account, we focus on optimization of the relaxivity of targeted agents. Relaxivity depends upon speciation, chemical structure, and dynamic processes, such as water exchange kinetics and rotational tumbling rates. We describe mechanistic studies that relate these factors to the observed relaxivities and use these findings as the basis of rational design of improved agents. In addition to traditional biochemical methods to characterize ligand-protein interactions, the presence of the metal ion enables more obscure biophysical techniques, such as relaxometry and electron nuclear double resonance, to be used to elucidate the mechanism of relaxivity differences. As a case study, we explore the mechanism of action of the serum-albumin-targeted angiography agent MS-325 and closely related compounds and show how small changes in the metal chelate can impact relaxivity. We found that, while protein binding generally improves relaxivity by slowing the tumbling rate of the complex, in some cases, the protein itself can also negatively affect hydration of the metal complex and/or inner-sphere water exchange. Drawing on these findings, we designed next-generation agents targeting albumin, fibrin, or collagen and incorporating up to four gadolinium chelates. Through judicious molecular design, we show that high-relaxivity complexes with high target affinity can be realized.
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Affiliation(s)
- Peter Caravan
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301, Charlestown, Massachusetts 02129
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21
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Design and function of metal complexes as contrast agents in MRI. ADVANCES IN INORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0898-8838(09)00202-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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23
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Hermann P, Kotek J, Kubícek V, Lukes I. Gadolinium(III) complexes as MRI contrast agents: ligand design and properties of the complexes. Dalton Trans 2008:3027-47. [PMID: 18521444 DOI: 10.1039/b719704g] [Citation(s) in RCA: 381] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetic resonance imaging is a commonly used diagnostic method in medicinal practice as well as in biological and preclinical research. Contrast agents (CAs), which are often applied are mostly based on Gd(III) complexes. In this paper, the ligand types and structures of their complexes on one side and a set of the physico-chemical parameters governing properties of the CAs on the other side are discussed. The solid-state structures of lanthanide(III) complexes of open-chain and macrocyclic ligands and their structural features are compared. Examples of tuning of ligand structures to alter the relaxometric properties of gadolinium(III) complexes as a number of coordinated water molecules, their residence time (exchange rate) or reorientation time of the complexes are given. Influence of the structural changes of the ligands on thermodynamic stability and kinetic inertness/lability of their lanthanide(III) complexes is discussed.
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Affiliation(s)
- Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Universita Karlova (Charles University), Hlavova 2030, 128 40, Prague 2, Czech Republic
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