1
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Welleman IM, Reeβing F, Boersma HH, Dierckx RAJO, Feringa BL, Szymanski W. The Development of a Smart Magnetic Resonance Imaging and Chemical Exchange Saturation Transfer Contrast Agent for the Imaging of Sulfatase Activity. Pharmaceuticals (Basel) 2023; 16:1439. [PMID: 37895910 PMCID: PMC10610007 DOI: 10.3390/ph16101439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023] Open
Abstract
The molecular imaging of biomarkers plays an increasing role in medical diagnostics. In particular, the imaging of enzyme activity is a promising approach, as it enables the use of its inherent catalytic activity for the amplification of an imaging signal. The increased activity of a sulfatase enzyme has been observed in several types of cancers. We describe the development and in vitro evaluation of molecular imaging agents that allow for the detection of sulfatase activity using the whole-body, non-invasive MRI and CEST imaging methods. This approach relies on a responsive ligand that features a sulfate ester moiety, which upon sulfatase-catalyzed hydrolysis undergoes an elimination process that changes the functional group, coordinating with the metal ion. When Gd3+ is used as the metal, the complex can be used for MRI, showing a 25% decrease at 0.23T and a 42% decrease at 4.7T in magnetic relaxivity after enzymatic conversion, thus providing a "switch-off" contrast agent. Conversely, the use of Yb3+ as the metal leads to a "switch-on" effect in the CEST imaging of sulfatase activity. Altogether, the results presented here provide a molecular basis and a proof-of-principle for the magnetic imaging of the activity of a key cancer biomarker.
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Affiliation(s)
- Ilse M. Welleman
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; (I.M.W.)
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Friederike Reeβing
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; (I.M.W.)
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Hendrikus H. Boersma
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; (I.M.W.)
- Department of Clinical Pharmacy and Pharmacology, Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Rudi A. J. O. Dierckx
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; (I.M.W.)
| | - Ben L. Feringa
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Wiktor Szymanski
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands; (I.M.W.)
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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2
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Meng Q, Wu M, Shang Z, Zhang Z, Zhang R. Responsive gadolinium(III) complex-based small molecule magnetic resonance imaging probes: Design, mechanism and application. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214398] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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3
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Leone L, Boccalon M, Ferrauto G, Fábián I, Baranyai Z, Tei L. Acid-catalyzed proton exchange as a novel approach for relaxivity enhancement in Gd-HPDO3A-like complexes. Chem Sci 2020; 11:7829-7835. [PMID: 34123071 PMCID: PMC8163333 DOI: 10.1039/d0sc02174a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A current challenge in medical diagnostics is how to obtain high MRI relaxation enhancement using GdIII-based contrast agents (CAs) containing the minimum concentration of GdIII ions. We report that in GdHPDO3A-like complexes a primary amide group located in close proximity to the coordinated hydroxyl group can provide a strong relaxivity enhancement at slightly acidic pH. A maximum relaxivity of r1 = 9.8 mM−1 s−1 (20 MHz, 298 K) at acidic pH was achieved, which is more than double that of clinically approved MRI contrast agents under identical conditions. This effect was found to strongly depend on the number of amide protons, i.e. it decreases with a secondary amide group and almost completely vanishes with a tertiary amide. This relaxivity enhancement is attributed to an acid-catalyzed proton exchange process between the metal-coordinated OH group, the amide protons and second sphere water molecules. The mechanism and kinetics of the corresponding H+ assisted exchange process are discussed in detail and a novel simultaneous double-site proton exchange mechanism is proposed. Furthermore, 1H and 17O NMR relaxometry, Chemical Exchange Saturation Transfer (CEST) on the corresponding EuIII complexes, and thermodynamic and kinetic studies are reported. These highlight the optimal physico-chemical properties required to achieve high relaxivity with this series of GdIII-complexes. Thus, proton exchange provides an important opportunity to enhance the relaxivity of contrast agents, providing that labile protons close to the paramagnetic center can contribute. A novel GdHPDO3A-like complex featuring primary amide side chain induces extraordinary high relaxivity by virtue of a simultaneous double-site proton exchange mechanism under slight acidic conditions.![]()
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Affiliation(s)
- Loredana Leone
- Department of Science and Technological Innovation, Università del Piemonte Orientale Viale T. Michel 11 15121 Alessandria Italy
| | - Mariangela Boccalon
- Bracco Imaging SpA, Bracco Research Center Via Ribes 5 10010 Colleretto Giacosa TO Italy
| | - Giuseppe Ferrauto
- Department of Molecular Biotechnology and Health Science, University of Turin Via Nizza 52 10126 Torino Italy
| | - István Fábián
- Department of Inorganic and Analytical Chemistry, MTA-DE Redox and Homogeneous Catalytic Reaction Mechanisms Research Group, University of Debrecen Egyetem tér 1. H-4032 Debrecen Hungary
| | - Zsolt Baranyai
- Bracco Imaging SpA, Bracco Research Center Via Ribes 5 10010 Colleretto Giacosa TO Italy
| | - Lorenzo Tei
- Department of Science and Technological Innovation, Università del Piemonte Orientale Viale T. Michel 11 15121 Alessandria Italy
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4
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Gao M, Shen B, Zhou J, Kapre R, Louie AY, Shaw JT. Synthesis and Comparative Evaluation of Photoswitchable Magnetic Resonance Imaging Contrast Agents. ACS OMEGA 2020; 5:14759-14766. [PMID: 32596613 PMCID: PMC7315594 DOI: 10.1021/acsomega.0c01534] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
A series of spiropyran (SP)-based magnetic resonance imaging (MRI) contrast agents have been synthesized and evaluated for changes in relaxivity resulting from irradiation with visible light. Both electron-donating and electron-withdrawing substituents were appended to the SP ring in order to study the electronic effects on the photochromic and relaxivity properties of these photoswitchable MRI contrast agents. Photoswitches lacking an electron-withdrawing substituent isomerize readily between the merocyanine and SP forms, while the addition of a nitro group prevents this process. Complexes capable of isomerizing were demonstrated to effect a change in the relaxivity of the appended gadolinium complex.
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Affiliation(s)
- Mingchun Gao
- Department
of Chemistry, University of California,
Davis, One Shields Avenue, Davis, California 95616, United States
| | - Bowen Shen
- Chemistry
Graduate Group, University of California,
Davis, One Shields Avenue, Davis, California 95616, United States
| | - Junhan Zhou
- Chemistry
Graduate Group, University of California,
Davis, One Shields Avenue, Davis, California 95616, United States
| | - Rohan Kapre
- Department
of Biomedical Engineering, University of
California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Angelique Y. Louie
- Chemistry
Graduate Group, University of California,
Davis, One Shields Avenue, Davis, California 95616, United States
- Department
of Biomedical Engineering, University of
California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Jared T. Shaw
- Department
of Chemistry, University of California,
Davis, One Shields Avenue, Davis, California 95616, United States
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5
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Abstract
Tyrosinase is a key enzyme that has long been considered as a biomarker for melanoma as it catalyzes the oxidation of tyrosine and l-DOPA in melanogenesis. Recent studies also suggest a link between tyrosinase activity and Parkinson's disease; however, the mechanism of tyrosinase-mediated melanin formation in the brain is poorly understood. To better understand this connection, more advanced tools for the detection of tyrosinase in the brain are required. Herein, we successfully designed and synthesized a tyrosinase-targeting Gd(iii)-based MR contrast agent Tyr-GBCA 1. Tyr-GBCA 1 was synthesized by linking m-hydroxyphenyl to Gd-DOTA via a self-immolative linker. Tyr-GBCA 1 shows a 21% increase in the T1 relaxation rate (R1) in the presence of tyrosinase in artificial cerebral spinal fluid. Furthermore, Tyr-GBCA 1 is unreactive to hydrogen peroxide, which is a potential interferent in oxidation-based tyrosinase sensing systems. The reaction mechanism of the probe was studied by electrospray ionization (ESI) mass spectrometry and supports the cleavage of a reaction site.
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Affiliation(s)
- Hyewon Seo
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA.
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6
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Li H, Meade TJ. Molecular Magnetic Resonance Imaging with Gd(III)-Based Contrast Agents: Challenges and Key Advances. J Am Chem Soc 2019; 141:17025-17041. [PMID: 31593630 DOI: 10.1021/jacs.9b09149] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In an era of personalized medicine, the clinical community has become increasingly focused on understanding diseases at the cellular and molecular levels. Magnetic resonance imaging (MRI) is a powerful imaging modality for acquiring anatomical and functional information. However, it has limited applications in the field of molecular imaging due to its low sensitivity. To expand the capability of MRI to encompass molecular imaging applications, we introduced bioresponsive Gd(III)-based magnetic resonance contrast agents (GBCAs) in 1997. Since that time, many research groups across the globe have developed new examples of bioresponsive GBCAs. These contrast agents have shown great promise for visualizing several biochemical processes, such as gene expression, neuronal signaling, and hormone secretion. They are designed to be conditionally retained, or activated, in vivo in response to specific biochemical events of interest. As a result, an observed MR signal change can serve as a read-out for molecular events. A significant challenge for these probes is how to utilize them for noninvasive diagnostic and theranostic applications. This Perspective focuses on the design strategies that underlie bioresponsive probes, and describes the key advances made in recent years that are facilitating their application in vivo and ultimately in clinical translation. While the field of bioresponsive agents is embryonic, it is clear that many solutions to the experimental and clinical radiologic problems of today will be overcome by the probes of tomorrow.
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Affiliation(s)
- Hao Li
- Departments of Chemistry, Molecular Biosciences, Neurobiology, and Radiology Northwestern University , Evanston , Illinois 60208 , United States
| | - Thomas J Meade
- Departments of Chemistry, Molecular Biosciences, Neurobiology, and Radiology Northwestern University , Evanston , Illinois 60208 , United States
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7
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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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8
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Leone L, Esteban-Gómez D, Platas-Iglesias C, Milanesio M, Tei L. Accelerating water exchange in GdIII–DO3A-derivatives by favouring the dissociative mechanism through hydrogen bonding. Chem Commun (Camb) 2019; 55:513-516. [DOI: 10.1039/c8cc08556k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The water exchange rate in GdIII-complexes increases by one order of magnitude due to H-bonding between the phenol(ate) group and the water molecules involved in the dissociative exchange mechanism.
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Affiliation(s)
- Loredana Leone
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT)
- Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- Viale T. Michel 11
- I-15121 Alessandria
- Italy
| | - David Esteban-Gómez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Facultade de Ciencias, Universidade da Coruña
- 15071 A Coruña
- Spain
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química
- Facultade de Ciencias, Universidade da Coruña
- 15071 A Coruña
- Spain
| | - Marco Milanesio
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT)
- Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- Viale T. Michel 11
- I-15121 Alessandria
- Italy
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica (DiSIT)
- Università degli Studi del Piemonte Orientale “Amedeo Avogadro”
- Viale T. Michel 11
- I-15121 Alessandria
- Italy
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9
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Giovenzana GB, Lattuada L, Negri R. Recent Advances in Bifunctional Paramagnetic Chelates for MRI. Isr J Chem 2017. [DOI: 10.1002/ijch.201700028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Giovanni B. Giovenzana
- Dipartimento di Scienze del Farmaco; Università del Piemonte Orientale “A. Avogadro”; L.go Donegani 2/3 I-28100 Novara Italy
| | - Luciano Lattuada
- Bracco Imaging SpA, Bracco Research Centre; Via Ribes 5 I-10010 Colleretto Giacosa TO, Italy
| | - Roberto Negri
- Dipartimento di Scienze del Farmaco; Università del Piemonte Orientale “A. Avogadro”; L.go Donegani 2/3 I-28100 Novara Italy
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10
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Krchová T, Herynek V, Gálisová A, Blahut J, Hermann P, Kotek J. Eu(III) Complex with DO3A-amino-phosphonate Ligand as a Concentration-Independent pH-Responsive Contrast Agent for Magnetic Resonance Spectroscopy (MRS). Inorg Chem 2017; 56:2078-2091. [PMID: 28170242 DOI: 10.1021/acs.inorgchem.6b02749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A new DOTA-like ligand H5do3aNP with a 2-[amino(methylphosphonic acid)]ethyl-coordinating pendant arm was prepared, and its coordinating properties were studied by NMR spectroscopy and potentiometry. The study revealed a rare slow exchange (on the 1H and 31P NMR time scale) between protonated and unprotonated complex species with a corresponding acidity constant pKA ∼ 8.0. This unusually slow time scale associated with protonation is caused by a significant geometric change from square-antiprismatic (SA) arrangement observed for protonated complex SA-[Eu(Hdo3aNP)]- to twisted-square-antiprismatic (TSA) arrangement found for deprotonated complex TSA-[Eu(do3aNP)]2-. This behavior results in simultaneous occurrence of the signals of both species in the 31P NMR spectra at approximately -118 and +70 ppm, respectively. Such an unprecedented difference in the chemical shifts between species differing by a proton is caused by a significant movement of the principal magnetic axis and by a change of phosphorus atom position in the coordination sphere of the central Eu(III) ion (i.e., by relative movement of the phosphorus atom with respect to the principal magnetic axis). It changes the sign of the paramagnetic contribution to the 31P NMR chemical shift. The properties discovered can be employed in the measurement of pH by MRS techniques as presented by proof-of-principle experiments on phantoms.
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Affiliation(s)
- Tereza Krchová
- Department of Inorganic Chemistry, Faculty of Science, Charles University , Hlavova 2030, Prague 2 128 43, Czech Republic
| | - Vít Herynek
- Department of Radiodiagnostic and Interventional Radiology, Magnetic Resonance Unit, Institute for Clinical and Experimental Medicine , Vídeňská 1958/9, Prague 4 140 21, Czech Republic
| | - Andrea Gálisová
- Department of Radiodiagnostic and Interventional Radiology, Magnetic Resonance Unit, Institute for Clinical and Experimental Medicine , Vídeňská 1958/9, Prague 4 140 21, Czech Republic
| | - Jan Blahut
- Department of Inorganic Chemistry, Faculty of Science, Charles University , Hlavova 2030, Prague 2 128 43, Czech Republic
| | - Petr Hermann
- Department of Inorganic Chemistry, Faculty of Science, Charles University , Hlavova 2030, Prague 2 128 43, Czech Republic
| | - Jan Kotek
- Department of Inorganic Chemistry, Faculty of Science, Charles University , Hlavova 2030, Prague 2 128 43, Czech Republic
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11
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Wacker A, Carniato F, Platas-Iglesias C, Esteban-Gomez D, Wester HJ, Tei L, Notni J. Dimer formation of GdDO3A-arylsulfonamide complexes causes loss of pH-dependency of relaxivity. Dalton Trans 2017; 46:16828-16836. [DOI: 10.1039/c7dt02985c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Coordination of peripheral carboxylates intended for bioconjugation dramatically changes the Gd(iii) coordination properties of DO3A-sulfonamide ligands.
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Affiliation(s)
- Anja Wacker
- Lehrstuhl für Pharmazeutische Radiochemie
- Technische Universität München
- D-85748 Garching
- Germany
| | - Fabio Carniato
- Dipartimento di Scienze e Innovazione Tecnologica
- Università del Piemonte Orientale “Amedeo Avogadro”
- I-15121 Alessandria
- Italy
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química Fundamental
- Facultade de Ciencias
- Universidade da Coruña
- A Coruña
- Spain
| | - David Esteban-Gomez
- Centro de Investigacións Científicas Avanzadas (CICA) and Departamento de Química Fundamental
- Facultade de Ciencias
- Universidade da Coruña
- A Coruña
- Spain
| | - Hans-Jürgen Wester
- Lehrstuhl für Pharmazeutische Radiochemie
- Technische Universität München
- D-85748 Garching
- Germany
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica
- Università del Piemonte Orientale “Amedeo Avogadro”
- I-15121 Alessandria
- Italy
| | - Johannes Notni
- Lehrstuhl für Pharmazeutische Radiochemie
- Technische Universität München
- D-85748 Garching
- Germany
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12
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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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13
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Zhu L, Yang Y, Farquhar K, Wang J, Tian C, Ranville J, Boyes SG. Surface Modification of Gd Nanoparticles with pH-Responsive Block Copolymers for Use As Smart MRI Contrast Agents. ACS APPLIED MATERIALS & INTERFACES 2016; 8:5040-5050. [PMID: 26790986 DOI: 10.1021/acsami.5b12463] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Despite recent advances in the understanding of fundamental cancer biology, cancer remains the second most common cause of death in the United States. One of the primary factors indicative of high cancer morbidity and mortality and aggressive cancer phenotypes is tumors with a low extracellular pH (pHe). Thus, the ability to measure tumor pHe in vivo using noninvasive and accurate techniques that also provide high spatiotemporal resolution has become increasingly important and is of great interest to researchers and clinicians. In an effort to develop a pH-responsive magnetic resonance imaging (MRI) contrast agent (CA) that has the potential to be used to measure tumor pHe, well-defined pH-responsive polymers, synthesized via reversible addition-fragmentation chain transfer polymerization, were attached to the surface of gadolinium-based nanoparticles (GdNPs) via a "grafting to" method after reduction of the thiocarbonylthio end groups. The successful modification of the GdNPs was verified by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and dynamic light scattering. The performance of the pH-responsive polymer modified GdNPs was then evaluated for potential use as smart MRI CAs via monitoring the relaxivity changes with changing environmental pH. The results suggested that the pH-responsive polymers can be used to effectively modify the GdNPs surface to prepare a smart contrast agent for MRI.
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Affiliation(s)
- Liping Zhu
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Yuan Yang
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Kirsten Farquhar
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Jingjing Wang
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Chixia Tian
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - James Ranville
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Stephen G Boyes
- Department of Chemistry and Geochemistry, Colorado School of Mines , Golden, Colorado 80401, United States
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14
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Regueiro-Figueroa M, Gündüz S, Patinec V, Logothetis NK, Esteban-Gómez D, Tripier R, Angelovski G, Platas-Iglesias C. Gd(3+)-Based Magnetic Resonance Imaging Contrast Agent Responsive to Zn(2+). Inorg Chem 2015; 54:10342-50. [PMID: 26468992 DOI: 10.1021/acs.inorgchem.5b01719] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report the heteroditopic ligand H5L, which contains a DO3A unit for Gd(3+) complexation connected to an NO2A moiety through a N-propylacetamide linker. The synthesis of the ligand followed a convergent route that involved the preparation of 1,4-bis(tert-butoxycarbonylmethyl)-1,4,7-triazacyclononane following the orthoamide strategy. The luminescence lifetimes of the Tb((5)D4) excited state measured for the TbL complex point to the absence of coordinated water molecules. Density functional theory calculations and (1)H NMR studies indicate that the EuL complex presents a square antiprismatic coordination in aqueous solution, where eight coordination is provided by the seven donor atoms of the DO3A unit and the amide oxygen atom of the N-propylacetamide linker. Addition of Zn(2+) to aqueous solutions of the TbL complex provokes a decrease of the emission intensity as the emission lifetime becomes shorter, which is a consequence of the coordination of a water molecule to the Tb(3+) ion upon Zn(2+) binding to the NO2A moiety. The relaxivity of the GdL complex recorded at 7 T (25 °C) increases by almost 150% in the presence of 1 equiv of Zn(2+), while Ca(2+) and Mg(2+) induced very small relaxivity changes. In vitro magnetic resonance imaging experiments confirmed the ability of GdL to provide response to the presence of Zn(2+).
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Affiliation(s)
- Martín Regueiro-Figueroa
- Grupo QUICOOR, Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Serhat Gündüz
- MR Neuroimaging Agents, Max Planck Institute for Biological Cybernetics , Spemannstr. 41, 72076 Tübingen, Germany
| | - Véronique Patinec
- UFR des Sciences et Techniques, Université de Bretagne Occidentale, UMR-CNRS 6521 , 6 avenue Victor le Gorgeu, C.S. 93837, 29238 BREST Cedex 3, France
| | - Nikos K Logothetis
- Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics , Tübingen, Germany.,Department of Imaging Science and Biomedical Engineering, University of Manchester , Manchester, U.K
| | - David Esteban-Gómez
- Grupo QUICOOR, Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Raphaël Tripier
- UFR des Sciences et Techniques, Université de Bretagne Occidentale, UMR-CNRS 6521 , 6 avenue Victor le Gorgeu, C.S. 93837, 29238 BREST Cedex 3, France
| | - Goran Angelovski
- MR Neuroimaging Agents, Max Planck Institute for Biological Cybernetics , Spemannstr. 41, 72076 Tübingen, Germany
| | - Carlos Platas-Iglesias
- Grupo QUICOOR, Centro de Investigaciones Científicas Avanzadas (CICA) and Departamento de Química Fundamental, Universidade da Coruña , Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain
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15
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Carron S, Li QY, Vander Elst L, Muller RN, Parac-Vogt TN, Capobianco JA. Assembly of near infra-red emitting upconverting nanoparticles and multiple Gd(III)-chelates as a potential bimodal contrast agent for MRI and optical imaging. Dalton Trans 2015; 44:11331-9. [PMID: 26011519 DOI: 10.1039/c5dt00919g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Linking multiple paramagnetic gadolinium(III)-chelates based on the 2-[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl]acetate (DOTA) ligand to the surface of NaGdF4:Yb(3+),Tm(3+) upconverting nanoparticles with an average particle size of 20 nm resulted in an assembly that has favorable properties for bimodal Magnetic Resonance Imaging (MRI) and Optical Imaging (OI). An improved synthetic pathway was used to couple the paramagnetic precursor to the nanoparticles. The nanoparticles were rendered water dispersible via citrate capping, leaving one acid group free for amide coupling with the mono-amino precursor of the DOTA ligand. Luminescence spectroscopy measurements have shown that the excitation of the nanoconstruct at 980 nm resulted in intense upconverted emission of thulium(III) at 800 nm. The assembly of several paramagnetic centers on the nanoparticle scaffold reduces the overall tumbling rate, resulting in enhanced longitudinal relaxation times and improved relaxivity. The proton NMRD profiles show a characteristic hump at higher frequencies, which is caused by the slow rotation of the nanoconstruct, resulting in r1 values of 25 mM(-1) s(-1) per gadolinium(III)-ion at 60 MHz and 310 K. This is a significant improvement compared to the Gd-DO3A-ethylamine precursor (4) for which a value of r1 of 3.23 mM(-1) s(-1) was observed under the same conditions. Theoretical fitting by two different approaches showed an increase of τR from 57.3 ps for the Gd-DO3A-ethylamine precursor (4) to 392.0 ps for the nanoconstruct, which is responsible for the overall substantial increase in relaxivity.
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Affiliation(s)
- Sophie Carron
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
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16
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Hingorani DV, Bernstein AS, Pagel MD. A review of responsive MRI contrast agents: 2005-2014. CONTRAST MEDIA & MOLECULAR IMAGING 2015; 10:245-65. [PMID: 25355685 PMCID: PMC4414668 DOI: 10.1002/cmmi.1629] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/06/2014] [Accepted: 09/18/2014] [Indexed: 12/18/2022]
Abstract
This review focuses on MRI contrast agents that are responsive to a change in a physiological biomarker. The response mechanisms are dependent on six physicochemical characteristics, including the accessibility of water to the agent, tumbling time, proton exchange rate, electron spin state, MR frequency or superparamagnetism of the agent. These characteristics can be affected by changes in concentrations or activities of enzymes, proteins, nucleic acids, metabolites, or metal ions, or changes in redox state, pH, temperature, or light. A total of 117 examples are presented, including ones that employ nuclei other than (1) H, which attests to the creativity of multidisciplinary research efforts to develop responsive MRI contrast agents.
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Affiliation(s)
- Dina V Hingorani
- Department of Chemistry and Biochemistry, University of Arizona, USA
| | - Adam S Bernstein
- Department of Biomedical Engineering, University of Arizona, USA
| | - Mark D Pagel
- Department of Chemistry and Biochemistry, University of Arizona, USA
- Department of Biomedical Engineering, University of Arizona, USA
- Department of Medical Imaging, University of Arizona, USA
- University of Arizona Cancer Center, University of Arizona, USA
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17
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Lewis MM, Milne M, Bartha R, Hudson RH. Dysprosium(III) and thulium(III) complexes of DO3A-monoanilides: an investigation of electronic effects on their relaxometric and amide-based PARACEST properties. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A series of 1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate monoamide (DO3A-monoanilide) complexes Dy3+ and Tm3+ were prepared and their magnetic properties evaluated in the context of their potential use as pH sensors. The ligands varied by para-substitution of the aniline moiety and represent electron-withdrawing and electron-donating groups. Only the Tm3+ complexes produced chemical exchange saturation transfer (CEST) spectra with CEST intensities due to the amide proton ranging from 1% to 8%. A maximum CEST signal was observed under slightly alkaline conditions (pH ∼8) when electron-donating groups were present, whereas the strongly electron-withdrawing nitro group produced a maximum CEST at neutral pH (pH = 7). The T1 and T2 relaxivities of the Dy3+ and Tm3+ complexes were also assessed. The T1 relaxivities of the Dy3+ and Tm3+ complexes were both low (r1 ≤ 0.3 mM−1 s−1, 25 °C, pH = 7) but, as expected, the Dy3+ complexes had much higher T2 relaxivities (r2 = 2–7 mM−1 s−1, 25 °C, pH = 7) as compared to the Tm3+-based chelates (r2 ≤ 0.09 mM−1 s−1, 25 °C, pH = 7).
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Affiliation(s)
- Melissa M. Lewis
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Mark Milne
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Robert Bartha
- Robarts Research Institute, Western University, 1151 Richmond St. N., London, ON N6A 5B7, Canada
| | - Robert H.E. Hudson
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
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18
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Krchová T, Kotek J, Jirák D, Havlíčková J, Císařová I, Hermann P. Lanthanide(III) complexes of aminoethyl-DO3A as PARACEST contrast agents based on decoordination of the weakly bound amino group. Dalton Trans 2014; 42:15735-47. [PMID: 24051547 DOI: 10.1039/c3dt52031e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2-Aminoethyl DOTA analogues with unsubstituted (H3L1), monomethylated (H3L2) and dimethylated (H3L3) amino groups were prepared by improved synthetic procedures. Their solid-state structures exhibit an extensive system of intramolecular hydrogen bonds, which is probably present in solution and leads to the rather high value of the last dissociation constant. The protonation sequence of H3L1 in solution corresponds to that found in the solid state. The stability constants of the H3L1 complexes with La(3+) and Gd(3+) (20.02 and 22.23, respectively) are similar to those of DO3A and the reduction of the pK(A) value of the pendant amino group from 10.51 in the free ligand to 6.06 and 5.83 in the La(3+) and Gd(3+) complexes, respectively, points to coordination of the amino group. It was confirmed in the solid state structure of the [Yb(L1)] complex, where disorder between the SA' and TSA' isomers was found. A similar situation is expected in solution, where a fast equilibration among the isomers hampers the unambiguous determination of the isomer ratio in solution. The PARACEST effect was observed in Eu(III)-H3L1/H3L2 and Yb(III)-H3L1/H3L2 complexes, being dependent on pH in the region of 4.5-7.5 and pH-independent in more alkaline solutions. The decrease of the PARACEST effect parallels with the increasing abundance of the complex protonated species, where the pendant amino group is not coordinating. Surprisingly, a small PARACEST effect was also observed in solutions of Eu(III)/Yb(III)-H3L3 complexes, where the pendant amino group is dimethylated. The effect is detectable in a narrow pH region, where both protonated and deprotonated complex species are present in equilibrium. The data points to the new mechanism of the PARACEST effect, where the slow coordination-decoordination of the pendant amine is coupled with the fast proton exchange between the free amino group and bulk water mediates the magnetization transfer. The pH-dependence of the effect was proved to be measurable by MRI and, thus, the complexes extend the family of pH-sensitive probes.
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Affiliation(s)
- Tereza Krchová
- Department of Inorganic Chemistry, Universita Karlova (Charles University), Hlavova 2030, 128 40 Prague 2, Czech Republic.
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19
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Affiliation(s)
- Marie C. Heffern
- Department of Chemistry, Molecular Biosciences, Neurobiology, Biomedical Engineering, and Radiology, Northwestern University, Evanston, Illinois 60208-3113
| | - Lauren M. Matosziuk
- Department of Chemistry, Molecular Biosciences, Neurobiology, Biomedical Engineering, and Radiology, Northwestern University, Evanston, Illinois 60208-3113
| | - Thomas J. Meade
- Department of Chemistry, Molecular Biosciences, Neurobiology, Biomedical Engineering, and Radiology, Northwestern University, Evanston, Illinois 60208-3113
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20
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Takács A, Napolitano R, Purgel M, Bényei AC, Zékány L, Brücher E, Tóth I, Baranyai Z, Aime S. Solution structures, stabilities, kinetics, and dynamics of DO3A and DO3A-sulphonamide complexes. Inorg Chem 2014; 53:2858-72. [PMID: 24564285 DOI: 10.1021/ic4025958] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The Gd(3+)-DO3A-arylsulphonamide (DO3A-SA) complex is a promising pH-sensitive MRI agent. The stability constants of the DO3A-SA and DO3A complexes formed with Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) ions are similar, whereas the logKLnL values of Ln(DO3A-SA) complexes are 2 orders of magnitude higher than those of the Ln(DO3A) complexes. The protonation constant (log KMHL) of the sulphonamide nitrogen in the Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) complexes is very similar to that of the free ligand, whereas the logKLnHL values of the Ln(DO3A-SA) complexes are lower by about 4 logK units, indicating a strong interaction between the Ln(3+) ions and the sulphonamide N atom. The Ln(HDO3A-SA) complexes are formed via triprotonated *Ln(H3DO3A-SA) intermediates which rearrange to the final complex in an OH(-)-assisted deprotonation process. The transmetalation reaction of Gd(HDO3A-SA) with Cu(2+) is very slow (t1/2 = 5.6 × 10(3) h at pH = 7.4), and it mainly occurs through proton-assisted dissociation of the complex. The (1)H and (13)C NMR spectra of the La-, Eu-, Y-, and Lu(DO3A-SA) complexes have been assigned using 2D correlation spectroscopy (COSY, EXSY, HSQC). Two sets of signals are observed for Eu-, Y-, and Lu(DO3A-SA), showing two coordination isomers in solution, that is, square antiprismatic (SAP) and twisted square antiprismatic (TSAP) geometries with ratios of 86-14, 93-7, and 94-6%, respectively. Line shape analysis of the (13)C NMR spectra of La-, Y- , and Lu(DO3A-SA) gives higher rates and lower activation entropy values compared to Ln(DOTA) for the arm rotation, which indicates that the Ln(DO3A-SA) complexes are less rigid due to the larger flexibility of the ethylene group in the sulphonamide pendant arm. The fast isomerization and the lower activation parameters of Ln(DO3A-SA) have been confirmed by theoretical calculations in vacuo and by using the polarizable continuum model. The solid state X-ray structure of Cu(H2DO3A-SA) shows distorted octahedral coordination. The coordination sites of Cu(2+) are occupied by two ring N- and two carboxylate O-atoms in equatorial position. The other two ring N-atoms complete the coordination sphere in axial positions. The solid state structure also indicates that a carboxylate O atom and the sulphonamide nitrogen are protonated and noncoordinated.
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Affiliation(s)
- Anett Takács
- Department of Inorganic and Analytical Chemistry, ‡MTA-DE Homogeneous Catalysis and Reaction Mechanisms Research Group, §Department of Physical Chemistry, University of Debrecen , H-4032 Debrecen, Egyetem tér 1, Hungary
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21
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Baranyai Z, Rolla GA, Negri R, Forgács A, Giovenzana GB, Tei L. Comprehensive Evaluation of the Physicochemical Properties of LnIIIComplexes of Aminoethyl-DO3A as pH-ResponsiveT1-MRI Contrast Agents. Chemistry 2014; 20:2933-44. [DOI: 10.1002/chem.201304063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Indexed: 11/10/2022]
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22
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Wang K, Peng H, Thurecht KJ, Puttick S, Whittaker AK. Biodegradable core crosslinked star polymer nanoparticles as19F MRI contrast agents for selective imaging. Polym Chem 2014. [DOI: 10.1039/c3py01311a] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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23
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Giardiello M, Botta M, Lowe MP. pH-Responsive Lanthanide Complexes Based on Reversible Ligation of a Diphenylphosphinamide. Inorg Chem 2013; 52:14264-9. [DOI: 10.1021/ic402205j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Marco Giardiello
- Department
of Chemistry, University
Road, University of Leicester, Leicester LE1 7RH, U.K
| | - Mauro Botta
- Dipartimento
di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “Amedeo Avogadro”, Viale Teresa Michel 11, I-15121 Alessandria, Italy
| | - Mark P. Lowe
- Department
of Chemistry, University
Road, University of Leicester, Leicester LE1 7RH, U.K
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24
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Napolitano R, Pariani G, Fedeli F, Baranyai Z, Aswendt M, Aime S, Gianolio E. Synthesis and relaxometric characterization of a MRI Gd-based probe responsive to glutamic acid decarboxylase enzymatic activity. J Med Chem 2013; 56:2466-77. [PMID: 23469759 DOI: 10.1021/jm301831f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Novel contrast agent based systems, which selectively visualize specific cells, e.g., neurons in the brain, would be of substantial importance for the fast developing field of molecular magnetic resonance imaging (MRI). We report here the synthesis and in vitro validation of a Gd(III)-based contrast agent designed to act as an MRI responsive probe for imaging the activity of the enzyme glutamic acid decarboxylase (GAD) present in neurons. Upon the action of the enzyme, the Gd(III) complex increases its hydration sphere and takes on a residual positive charge that promotes its binding to endogenous macromolecules. Both effects contribute in a synergic way to generate a marked relaxation enhancement, which directly reports enzyme activity and will allow activity detection of GAD positive cells in vitro and in vivo selectively.
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Affiliation(s)
- Roberta Napolitano
- Department of Molecular Biotechnologies and Health Sciences and Molecular Imaging Center, University of Torino, Turin, Italy
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25
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Vologdin N, Rolla GA, Botta M, Tei L. Orthogonal synthesis of a heterodimeric ligand for the development of the GdIII–GaIII ditopic complex as a potential pH-sensitive MRI/PET probe. Org Biomol Chem 2013; 11:1683-90. [DOI: 10.1039/c2ob27200h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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26
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Promising strategies for Gd-based responsive magnetic resonance imaging contrast agents. Curr Opin Chem Biol 2012; 17:158-66. [PMID: 23141598 DOI: 10.1016/j.cbpa.2012.10.031] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 10/18/2012] [Accepted: 10/20/2012] [Indexed: 11/22/2022]
Abstract
Magnetic resonance imaging is a powerful imaging modality that is often coupled with paramagnetic contrast agents based on gadolinium to enhance sensitivity and image quality. Responsive contrast agents are key to furthering the diagnostic potential of MRI, both to provide anatomical information and to discern biochemical activity. Recent design of responsive gadolinium-based T₁ agents has made interesting progress, with the development of novel complexes which sense their chemical environment through changes in the coordination of water molecules, the molecular tumbling time or the number of metal centres. Particular promising design strategies include the use of multimeric systems, and the development of dual imaging probes.
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