1
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Mc Veigh M, Bellan LM. Microfluidic synthesis of radiotracers: recent developments and commercialization prospects. LAB ON A CHIP 2024; 24:1226-1243. [PMID: 38165824 DOI: 10.1039/d3lc00779k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Positron emission tomography (PET) is a powerful diagnostic tool that holds incredible potential for clinicians to track a wide variety of biological processes using specialized radiotracers. Currently, however, a single radiotracer accounts for over 95% of procedures, largely due to the cost of radiotracer synthesis. Microfluidic platforms provide a solution to this problem by enabling a dose-on-demand pipeline in which a single benchtop platform would synthesize a wide array of radiotracers. In this review, we will explore the field of microfluidic production of radiotracers from early research to current development. Furthermore, the benefits and drawbacks of different microfluidic reactor designs will be analyzed. Lastly, we will discuss the various engineering considerations that must be addressed to create a fully developed, commercially effective platform that can usher the field from research and development to commercialization.
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Affiliation(s)
- Mark Mc Veigh
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN, 37235, USA
| | - Leon M Bellan
- Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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2
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Elkawad H, Xu Y, Tian M, Jin C, Zhang H, Yu K, He Q. Recent advances in microfluidic devices for radiosynthesis of PET‐imaging probes. Chem Asian J 2022; 17:e202200579. [PMID: 35909081 DOI: 10.1002/asia.202200579] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/29/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Husamelden Elkawad
- The second affiliated hospital of Zhejiang University Nuclear Medicine and PET center CHINA
| | - Yangyang Xu
- Zhejiang University b. College of Chemical & Biological Engineering CHINA
| | - Mei Tian
- The second affiliated hospital of Zhejiang University Nuclear Medicine & PET center CHINA
| | - Chenyang Jin
- Zhejiang University b. College of Chemical & Biological Engineering CHINA
| | - Hong Zhang
- The second affiliated hospital of Zhejiang University b. College of Chemical & Biological Engineering CHINA
| | - Kaiwu Yu
- Zhejiang University b. College of Chemical & Biological Engineering CHINA
| | - Qinggang He
- Zhejiang University Chemical Engineering 38 Zheda Rd. 310027 Hangzhou CHINA
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3
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Duan X, Wang X, Chen X, Zhang J. Continuous and Selective Hydrogenation of Heterocyclic Nitroaromatics in a Micropacked Bed Reactor. Org Process Res Dev 2021. [DOI: 10.1021/acs.oprd.1c00164] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaonan Duan
- The State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Xuepeng Wang
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, P. R. China
| | - Xingkun Chen
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, P. R. China
| | - Jisong Zhang
- The State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
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4
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Kaur T, Brooks AF, Hockley BG, Torres J, Henderson BD, Scott PJH, Shao X. An updated synthesis of N 1 '-([ 11 C]methyl)naltrindole for positron emission tomography imaging of the delta opioid receptor. J Labelled Comp Radiopharm 2020; 64:187-193. [PMID: 33274468 DOI: 10.1002/jlcr.3898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 11/08/2022]
Abstract
A new method for the synthesis of the highly selective delta opioid receptor (DOR) antagonist radiotracer N1 '-([11 C]methyl)naltrindole ([11 C]MeNTI) is described. The original synthesis required hydrogenation of a benzyl protecting group after 11 C-labeling, which is challenging in modern radiochemistry laboratories that tend to be heavily automated and operate according to current good manufacturing practice. To address this challenge, we describe development of a novel MeNTI precursor bearing a methoxymethyl acetal (MOM) protecting group, which is easily removed with HCl, and employ it in an updated synthesis of [11 C]MeNTI. The new synthesis is fully automated and validated for clinical use. The total synthesis time is 45 min and provides [11 C]MeNTI in good activity yield (49 ± 8 mCi), molar activity (3,926 ± 326 Ci/mmol) and radiochemical purity (97% ± 2%).
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Affiliation(s)
- Tanpreet Kaur
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Brian G Hockley
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Jovany Torres
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Bradford D Henderson
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xia Shao
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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5
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Klenner MA, Fraser BH, Moon V, Evans BJ, Massi M, Pascali G. Telescoping the Synthesis of the [
18
F]CABS13 Alzheimer's Disease Radiopharmaceutical via Flow Microfluidic Rhenium(I) Complexations. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Mitchell A. Klenner
- National Deuteration Facility (NDF) & Human Health Australian Nuclear Science and Technology Organisation (ANSTO) 2234 Lucas Heights NSW Australia
- School of Molecular and Life Sciences Curtin University 6102 Bentley WA. Australia
| | - Benjamin H. Fraser
- National Deuteration Facility (NDF) & Human Health Australian Nuclear Science and Technology Organisation (ANSTO) 2234 Lucas Heights NSW Australia
| | - Vaughan Moon
- National Deuteration Facility (NDF) & Human Health Australian Nuclear Science and Technology Organisation (ANSTO) 2234 Lucas Heights NSW Australia
- Department of Molecular Sciences Macquarie University 2109 Macquarie Park NSW Australia
| | - Brendan J. Evans
- National Deuteration Facility (NDF) & Human Health Australian Nuclear Science and Technology Organisation (ANSTO) 2234 Lucas Heights NSW Australia
- Department of Molecular Sciences Macquarie University 2109 Macquarie Park NSW Australia
| | - Massimiliano Massi
- School of Molecular and Life Sciences Curtin University 6102 Bentley WA. Australia
| | - Giancarlo Pascali
- National Deuteration Facility (NDF) & Human Health Australian Nuclear Science and Technology Organisation (ANSTO) 2234 Lucas Heights NSW Australia
- Prince of Wales Hospital 2031 Randwick NSW Australia
- School of Chemistry University of New South Wales (UNSW) 2052 Kensington NSW Australia
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6
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Klenner MA, Darwish T, Fraser BH, Massi M, Pascali G. Labeled Rhenium Complexes: Radiofluorination, α-MSH Cyclization, and Deuterium Substitutions. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mitchell A. Klenner
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales, Australia 2234
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia 6102
| | - Tamim Darwish
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales, Australia 2234
| | - Benjamin H. Fraser
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales, Australia 2234
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia 6102
| | - Giancarlo Pascali
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales, Australia 2234
- Prince of Wales Hospital, Randwick, New South Wales, Australia 2031
- School of Chemistry, University of New South Wales (UNSW), Kensington, New South Wales, Australia 2052
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7
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Knapp KA, Nickels ML, Manning HC. The Current Role of Microfluidics in Radiofluorination Chemistry. Mol Imaging Biol 2019; 22:463-475. [DOI: 10.1007/s11307-019-01414-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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8
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Basuli F, Zhang X, Brugarolas P, Reich DS, Swenson RE. An efficient new method for the synthesis of 3-[ 18 F]fluoro-4-aminopyridine via Yamada-Curtius rearrangement. J Labelled Comp Radiopharm 2018; 61:112-117. [PMID: 28870001 PMCID: PMC5992582 DOI: 10.1002/jlcr.3560] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/31/2017] [Accepted: 08/29/2017] [Indexed: 01/10/2023]
Abstract
4-Aminopyridine is a clinically approved drug to improve motor symptoms in multiple sclerosis. A fluorine-18-labeled derivative of this drug, 3-[18 F]fluoro-4-aminopyridine, is currently under investigation for positron emission tomography (PET) imaging of demyelination. Herein, the Yamada-Curtius reaction has been successfully applied for the preparation of this PET radioligand with a better radiochemical yield and improved specific activity. The overall radiochemical yield was 5 to 15% (n = 12, uncorrected) with a specific activity of 37 to 148 GBq/μmol (end of synthesis) in a 90 minute synthesis time. It is expected that this 1 pot Yamada-Curtius reaction can be used to prepare similar fluorine-18-labeled amino substituted heterocycles.
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Affiliation(s)
- Falguni Basuli
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Xiang Zhang
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Pedro Brugarolas
- Department of Neurology, The University of Chicago, Chicago, IL, USA
| | - Daniel S. Reich
- Translational Neuroradiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Rolf E. Swenson
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
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9
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Krishnan HS, Bernard-Gauthier V, Placzek MS, Dahl K, Narayanaswami V, Livni E, Chen Z, Yang J, Collier TL, Ran C, Hooker JM, Liang SH, Vasdev N. Metal Protein-Attenuating Compound for PET Neuroimaging: Synthesis and Preclinical Evaluation of [11C]PBT2. Mol Pharm 2018; 15:695-702. [DOI: 10.1021/acs.molpharmaceut.7b00936] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Hema S. Krishnan
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Vadim Bernard-Gauthier
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Michael S. Placzek
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Kenneth Dahl
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Vidya Narayanaswami
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Elijahu Livni
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Jing Yang
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Thomas L. Collier
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Research
and Development, Advion Inc., Ithaca, New York 14850, United States
| | - Chongzhao Ran
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Jacob M. Hooker
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Steven H. Liang
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Neil Vasdev
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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10
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Carlucci G, Carney B, Sadique A, Vansteene A, Tang J, Reiner T. Evaluation of [ 18F]-ATRi as PET tracer for in vivo imaging of ATR in mouse models of brain cancer. Nucl Med Biol 2017; 48:9-15. [PMID: 28157626 DOI: 10.1016/j.nucmedbio.2017.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/28/2016] [Accepted: 01/05/2017] [Indexed: 10/20/2022]
Abstract
RATIONALE Ataxia telangiectasia and Rad3-related (ATR) threonine serine kinase is one of the key elements in orchestrating the DNA damage response (DDR). As such, inhibition of ATR can amplify the effects of chemo- and radiation-therapy, and several ATR inhibitors (ATRi) have already undergone clinical testing in cancer. For more accurate patient selection, monitoring and staging, real-time in vivo imaging of ATR could be invaluable; the development of appropriate imaging agents has remained a major challenge. METHODS 3-amino-N-(4-[18F]phenyl)-6-(4-(methylsulfonyl)phenyl)pyrazine-2-carboxamide ([18F]-ATRi), a close analogue of Ve-821, (a clinical ATRi candidate), was readily accomplished similarly to already established synthetic procedures. Structurally, 18F was introduced at the 4-position of the aromatic ring of Ve-821 for generating a labeled ATR inhibitor. In vitro experiments were conducted in U251 MG glioblastoma cell lines and ex vivo biodistribution were performed in subcutaneous U251 MG xenograft bearing athymic nude mice following microPET imaging. RESULTS [18F]-ATRi has a similar pharmacokinetic profile to that of Ve-821. Using an U251 MG glioblastoma mouse model, we evaluated the in vivo binding efficiency of [18F]-ATRi. Blood and tumor showed a statistically significant difference between mice injected with only the probe or following blocking experiment with Ve-821 (1.48±0.40%ID/g vs. 0.46±0.12%ID/g in tumor and 1.85±0.47%ID/g vs. 0.84±0.3%ID/g in blood respectively). CONCLUSIONS [18F]-ATRi represents the first 18F positron emission tomography (PET) ATR imaging agent, and is designed on a low nanomolar and clinically relevant ATR inhibitor.
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Affiliation(s)
- Giuseppe Carlucci
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Brandon Carney
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA; Department of Chemistry, Hunter College and PhD Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10018, USA
| | - Ahmad Sadique
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Axel Vansteene
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Jun Tang
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Thomas Reiner
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA; Weill Cornell Medical College, New York, NY, 10065, USA.
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11
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Balti M, Efrit ML, Leadbeater NE. Preparation of vinyl ethers using a Wittig approach, and their subsequent hydrogenation employing continuous-flow processing. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.03.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Rotstein BH, Wang L, Liu RY, Patteson J, Kwan EE, Vasdev N, Liang SH. Mechanistic Studies and Radiofluorination of Structurally Diverse Pharmaceuticals with Spirocyclic Iodonium(III) Ylides. Chem Sci 2016; 7:4407-4417. [PMID: 27540460 PMCID: PMC4987086 DOI: 10.1039/c6sc00197a] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Theoretical studies provide insight into radiofluorination of non-activated electron-rich and sterically hindered 18F-arenes using a new class of adamantyl-based spirocyclic iodonium(iii) ylide precursors.
Synthesis of non-activated electron-rich and sterically hindered 18F-arenes remains a major challenge due to limitations of existing radiofluorination methodologies. Herein, we report on our mechanistic investigations of spirocyclic iodonium(iii) ylide precursors for arene radiofluorination, including their reactivity, selectivity, and stability with no-carrier-added [18F]fluoride. Benchmark calculations at the G2[ECP] level indicate that pseudorotation and reductive elimination at iodine(iii) can be modeled well by appropriately selected dispersion-corrected density functional methods. Modeling of the reaction pathways show that fluoride–iodonium(iii) adduct intermediates are strongly activated and highly regioselective for reductive elimination of the desired [18F]fluoroarenes (difference in barriers, ΔΔG‡ > 25 kcal mol–1). The advantage of spirocyclic auxiliaries is further supported by NMR spectroscopy studies, which bolster evidence for underlying decomposition processes which can be overcome for radiofluorination of iodonium(iii) precursors. Using a novel adamantyl auxiliary, sterically hindered iodonium ylides have been developed to enable highly efficient radiofluorination of electron-rich arenes, including fragments of pharmaceutically relevant nitrogen-containing heterocycles and tertiary amines. Furthermore, this methodology has been applied for the syntheses of the radiopharmaceuticals 6-[18F]fluoro-meta-tyrosine ([18F]FMT, 11 ± 1% isolated radiochemical yield, non-decay-corrected (RCY, n.d.c.), n = 3), and meta-[18F]fluorobenzylguanidine ([18F]mFBG, 14 ± 1% isolated RCY, n.d.c., n = 3) which cannot be directly radiolabeled using conventional nucleophilic aromatic substitution with [18F]fluoride.
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Affiliation(s)
- Benjamin H Rotstein
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Lu Wang
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Richard Y Liu
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, United States of America
| | - Jon Patteson
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Eugene E Kwan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, United States of America
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
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13
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Trojanowicz M. Flow chemistry vs. flow analysis. Talanta 2016; 146:621-40. [DOI: 10.1016/j.talanta.2015.07.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 07/07/2015] [Accepted: 07/13/2015] [Indexed: 11/28/2022]
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14
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Rehm TH. Photochemical Fluorination Reactions - A Promising Research Field for Continuous-Flow Synthesis. Chem Eng Technol 2015. [DOI: 10.1002/ceat.201500195] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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15
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Liang SH, Southon AG, Fraser BH, Krause-Heuer AM, Zhang B, Shoup TM, Lewis R, Volitakis I, Han Y, Greguric I, Bush AI, Vasdev N. Novel Fluorinated 8-Hydroxyquinoline Based Metal Ionophores for Exploring the Metal Hypothesis of Alzheimer's Disease. ACS Med Chem Lett 2015; 6:1025-9. [PMID: 26396692 DOI: 10.1021/acsmedchemlett.5b00281] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 08/09/2015] [Indexed: 12/14/2022] Open
Abstract
Zinc, copper, and iron ions are involved in amyloid-beta (Aβ) deposition and stabilization in Alzheimer's disease (AD). Consequently, metal binding agents that prevent metal-Aβ interaction and lead to the dissolution of Aβ deposits have become well sought therapeutic and diagnostic targets. However, direct intervention between diseases and metal abnormalities has been challenging and is partially attributed to the lack of a suitable agent to determine and modify metal concentration and distribution in vivo. In the search of metal ionophores, we have identified several promising chemical entities by strategic fluorination of 8-hydroxyquinoline drugs, clioquinol, and PBT2. Compounds 15-17 and 28-30 showed exceptional metal ionophore ability (6-40-fold increase of copper uptake and >2-fold increase of zinc uptake) and inhibition of zinc induced Aβ oligomerization (EC50s < ∼5 μM). These compounds are suitable for further development as drug candidates and/or positron emission tomography (PET) biomarkers if radiolabeled with (18)F.
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Affiliation(s)
- Steven H. Liang
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Adam G. Southon
- Florey
Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Benjamin H. Fraser
- Radiopharmaceutical
Research and Development, Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales 2232, Australia
| | - Anwen M. Krause-Heuer
- Radiopharmaceutical
Research and Development, Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales 2232, Australia
| | - Bo Zhang
- Radiopharmaceutical
Research and Development, Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales 2232, Australia
| | - Timothy M. Shoup
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Rebecca Lewis
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Irene Volitakis
- Florey
Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Yifeng Han
- The
Key Laboratory of Advanced Textile Materials and Manufacturing Technology,
Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Ivan Greguric
- Radiopharmaceutical
Research and Development, Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales 2232, Australia
| | - Ashley I. Bush
- Florey
Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Neil Vasdev
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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16
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Abstract
The logic of total synthesis transformed a stagnant state of medicinal and synthetic organic chemistry when there was a paucity of methods and reagents to synthesize drug molecules and/or natural products. Molecular imaging by positron emission tomography (PET) is now experiencing a renaissance in the way radiopharmaceuticals for molecular imaging are synthesized, however, a paradigm shift is desperately needed in the discovery pipeline to accelerate in vivo imaging studies. A significant challenge in radiochemistry is the limited choice of labeled reagents (or building blocks) available for the synthesis of novel radiopharmaceuticals with the most commonly used short-lived radionuclides carbon-11 (11C; half-life ~20 minutes) and fluorine-18 (18F; half-life ~2 hours). In fact, most drugs cannot be labeled with 11C or 18F due to a lack of efficient and diverse radiosynthetic methods. In general, routine radiopharmaceutical production relies on the incorporation of the isotope at the last or penultimate step of synthesis, ideally within one half-life of the radionuclide, to maximize radiochemical yields and specific activities thereby reducing losses due to radioactive decay. Reliance on radiochemistry conducted within the constraints of an automated synthesis unit ("box") has stifled the exploration of multi-step reactions with short-lived radionuclides. Radiopharmaceutical synthesis can be transformed by considering logic of total synthesis to develop novel approaches for 11C- and 18F-radiolabeling complex molecules via retrosynthetic analysis and multi-step reactions. As a result of such exploration, new methods, reagents and radiopharmaceuticals for in vivo imaging studies are discovered. A new avenue to develop radiotracers that were previously unattainable due to the lack of efficient radiosynthetic methods is necessary to work towards our ultimate, albeit impossible goal - the concept we term total radiosynthesis - to radiolabel virtually any molecule. As with the vast majority of drugs, most radiotracers also fail, therefore expeditious evaluation of tracers in preclinical models prior to optimization or derivatization of the lead molecules/drugs is necessary. Furthermore the exact position of the 11C and 18F radionuclide in tracers is often critical for metabolic considerations, and flexible methodologies to introduce the radiolabel are needed. Using the principles of total synthesis our laboratory and others have shown that multi-step radiochemical reactions are indeed suitable for preclinical and even clinical use. As the goal of total synthesis is to be concise, we have also simplified the syntheses of radiopharmaceuticals. We are presently developing new strategies via [11C]CO2 fixation which has enabled library radiosynthesis as well as labeling non-activated arenes using [18F]fluoride via iodonium ylides. Both of which have proven to be suitable for human PET imaging. We concurrently utilize state-of-the-art automation technologies including microfluidic flow chemistry and rapid purification strategies for radiopharmaceutical production. In this account we highlight how total radiosynthesis has impacted our radiochemistry program, with prominent examples from others, focusing on its impact towards preclinical and clinical research studies.
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Affiliation(s)
- Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
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17
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Liang SH, Holland JP, Stephenson NA, Kassenbrock A, Rotstein BH, Daignault CP, Lewis R, Collier L, Hooker JM, Vasdev N. PET neuroimaging studies of [(18)F]CABS13 in a double transgenic mouse model of Alzheimer's disease and nonhuman primates. ACS Chem Neurosci 2015; 6:535-41. [PMID: 25776827 DOI: 10.1021/acschemneuro.5b00055] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Fluorine-18 labeled 2-fluoro-8-hydroxyquinoline ([(18)F]CABS13) is a promising positron emission tomography (PET) radiopharmaceutical based on a metal chelator developed to probe the "metal hypothesis of Alzheimer's disease". Herein, a practical radiosynthesis of [(18)F]CABS13 was achieved by radiofluorination followed by deprotection of an O-benzyloxymethyl group. Automated production and formulation of [(18)F]CABS13 resulted in 19 ± 5% uncorrected radiochemical yield, relative to starting [(18)F]fluoride, with ≥95% chemical and radiochemical purities, and high specific activity (>2.5 Ci/μmol) within 80 min. Temporal PET neuroimaging studies were carried out in female transgenic B6C3-Tg(APPswe,PSEN 1dE9)85Dbo/J (APP/PS1) and age-matched wild-type (WT) B6C3F1/J control mice at 3, 7, and 10 months of age. [(18)F]CABS13 showed an overall higher uptake and retention of radioactivity in the central nervous system of APP/PS1 mice versus WT mice with increasing age. However, PET/magnetic resonance imaging in normal nonhuman primates revealed that the tracer had low uptake in the brain and rapid formation of a hydrophilic radiometabolite. Identification of more metabolically stable (18)F-hydroxyquinolines that can be readily accessed by the radiochemical strategy presented herein is underway.
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Affiliation(s)
- Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Jason P. Holland
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Nickeisha A. Stephenson
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Alina Kassenbrock
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Benjamin H. Rotstein
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Cory P. Daignault
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Rebecca Lewis
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Lee Collier
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
- Advion, Inc., Ithaca, New York 14850, United States
| | - Jacob M. Hooker
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
- Athinoula
A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging & Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
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18
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Liang SH, Yokell DL, Normandin MD, Rice PA, Jackson RN, Shoup TM, Brady TJ, El Fakhri G, Collier TL, Vasdev N. First human use of a radiopharmaceutical prepared by continuous-flow microfluidic radiofluorination: proof of concept with the tau imaging agent [18F]T807. Mol Imaging 2015; 13. [PMID: 25248283 DOI: 10.2310/7290.2014.00025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite extensive preclinical imaging with radiotracers developed by continuous-flow microfluidics, a positron emission tomographic (PET) radiopharmaceutical has not been reported for human imaging studies by this technology. The goal of this study was to validate the synthesis of the tau radiopharmaceutical 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([18F]T807) and perform first-in-human PET scanning enabled by microfluidic flow chemistry. [18F]T807 was synthesized by our modified one-step method and adapted to suit a commercial microfluidic flow chemistry module. For this proof of concept, the flow system was integrated to a GE Tracerlab FXFN unit for high-performance liquid chromatography purification and formulation. Three consecutive productions of [18F]T807 were conducted to validate this radiopharmaceutical. Uncorrected radiochemical yields of 17 ± 1% of crude [18F]T807 (≈ 500 mCi, radiochemical purity 95%) were obtained from the microfluidic device. The crude material was then purified, and > 100 mCi of the final product was obtained in an overall uncorrected radiochemical yield of 5 ± 1% (n = 3), relative to starting [18F]fluoride (end of bombardment), with high radiochemical purity (≥ 99%) and high specific activities (6 Ci/μmol) in 100 minutes. A clinical research study was carried out with [18F]T807, representing the first reported human imaging study with a radiopharmaceutical prepared by this technology.
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Dahl K, Schou M, Ulin J, Sjöberg CO, Farde L, Halldin C. 11C-carbonylation reactions using gas–liquid segmented microfluidics. RSC Adv 2015. [DOI: 10.1039/c5ra20646d] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A novel gas–liquid segmented microfluidic platform has been developed, allowing for the direct access to11C-labelled drug-like molecules.
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Affiliation(s)
- Kenneth Dahl
- Karolinska Institutet
- Department of Clinical Neuroscience
- Centre for Psychiatric Research
- Karolinska Hospital
- S-171 76 Stockholm
| | - Magnus Schou
- AstraZeneca Translational Science Centre
- Department of Clinical Neuroscience
- Karolinska Institutet
- S-171 76 Stockholm
- Sweden
| | - Johan Ulin
- Bencar AB
- Uppsala Science Park
- S-751 83 Uppsala
- Sweden
| | | | - Lars Farde
- Karolinska Institutet
- Department of Clinical Neuroscience
- Centre for Psychiatric Research
- Karolinska Hospital
- S-171 76 Stockholm
| | - Christer Halldin
- Karolinska Institutet
- Department of Clinical Neuroscience
- Centre for Psychiatric Research
- Karolinska Hospital
- S-171 76 Stockholm
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20
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Jacobson O, Kiesewetter DO, Chen X. Fluorine-18 radiochemistry, labeling strategies and synthetic routes. Bioconjug Chem 2014; 26:1-18. [PMID: 25473848 PMCID: PMC4306521 DOI: 10.1021/bc500475e] [Citation(s) in RCA: 307] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Fluorine-18 is the most frequently used radioisotope in positron emission tomography (PET) radiopharmaceuticals in both clinical and preclinical research. Its physical and nuclear characteristics (97% β(+) decay, 109.7 min half-life, 635 keV positron energy), along with high specific activity and ease of large scale production, make it an attractive nuclide for radiochemical labeling and molecular imaging. Versatile chemistry including nucleophilic and electrophilic substitutions allows direct or indirect introduction of (18)F into molecules of interest. The significant increase in (18)F radiotracers for PET imaging accentuates the need for simple and efficient (18)F-labeling procedures. In this review, we will describe the current radiosynthesis routes and strategies for (18)F labeling of small molecules and biomolecules.
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Affiliation(s)
- Orit Jacobson
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health , Bethesda, Maryland 20892, United States
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21
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Pascali G, Matesic L, Collier TL, Wyatt N, Fraser BH, Pham TQ, Salvadori PA, Greguric I. Optimization of nucleophilic ¹⁸F radiofluorinations using a microfluidic reaction approach. Nat Protoc 2014; 9:2017-29. [PMID: 25079426 DOI: 10.1038/nprot.2014.137] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microfluidic techniques are increasingly being used to synthesize positron-emitting radiopharmaceuticals. Several reports demonstrate higher incorporation yields, with shorter reaction times and reduced amounts of reagents compared with traditional vessel-based techniques. Microfluidic techniques, therefore, have tremendous potential for allowing rapid and cost-effective optimization of new radiotracers. This protocol describes the implementation of a suitable microfluidic process to optimize classical (18)F radiofluorination reactions by rationalizing the time and reagents used. Reaction optimization varies depending on the systems used, and it typically involves 5-10 experimental days of up to 4 h of sample collection and analysis. In particular, the protocol allows optimization of the key fluidic parameters in the first tier of experiments: reaction temperature, residence time and reagent ratio. Other parameters, such as solvent, activating agent and precursor concentration need to be stated before the experimental runs. Once the optimal set of parameters is found, repeatability and scalability are also tested in the second tier of experiments. This protocol allows the standardization of a microfluidic methodology that could be applied in any radiochemistry laboratory, in order to enable rapid and efficient radiosynthesis of new and existing [(18)F]-radiotracers. Here we show how this method can be applied to the radiofluorination optimization of [(18)F]-MEL050, a melanoma tumor imaging agent. This approach, if integrated into a good manufacturing practice (GMP) framework, could result in the reduction of materials and the time required to bring new radiotracers toward preclinical and clinical applications.
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Affiliation(s)
- Giancarlo Pascali
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Lidia Matesic
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Thomas L Collier
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Naomi Wyatt
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Benjamin H Fraser
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Tien Q Pham
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Piero A Salvadori
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Ivan Greguric
- LifeSciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
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22
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Ermert J. 18F-labelled intermediates for radiosynthesis by modular build-up reactions: newer developments. BIOMED RESEARCH INTERNATIONAL 2014; 2014:812973. [PMID: 25343144 PMCID: PMC4197889 DOI: 10.1155/2014/812973] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 05/12/2014] [Indexed: 12/20/2022]
Abstract
This brief review gives an overview of newer developments in (18)F-chemistry with the focus on small (18)F-labelled molecules as intermediates for modular build-up syntheses. The short half-life (<2 h) of the radionuclide requires efficient syntheses of these intermediates considering that multistep syntheses are often time consuming and characterized by a loss of yield in each reaction step. Recent examples of improved synthesis of (18)F-labelled intermediates show new possibilities for no-carrier-added ring-fluorinated arenes, novel intermediates for tri[(18)F]fluoromethylation reactions, and (18)F-fluorovinylation methods.
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Affiliation(s)
- Johannes Ermert
- Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich, 52425 Jülich, Germany
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23
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Pascali G, Berton A, DeSimone M, Wyatt N, Matesic L, Greguric I, Salvadori PA. Hardware and software modifications on the Advion NanoTek microfluidic platform to extend flexibility for radiochemical synthesis. Appl Radiat Isot 2014; 84:40-7. [DOI: 10.1016/j.apradiso.2013.10.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/14/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
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24
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Liang SH, Yokell DL, Jackson RN, Rice PA, Callahan R, Johnson KA, Alagille D, Tamagnan G, Collier TL, Vasdev N. Microfluidic continuous-flow radiosynthesis of [ 18F]FPEB suitable for human PET imaging. MEDCHEMCOMM 2014; 5:432-435. [PMID: 25431646 DOI: 10.1039/c3md00335c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The synthesis of fluorine-18 labeled 3-fluoro-5-[(pyridin-3-yl)ethynyl] benzonitrile ([18F]FPEB) for imaging metabotropic glutamate receptor subtype type 5 (mGluR5) was achieved with a commercial continuous-flow microfluidics device. This work represents the first positron emission tomography (PET) radiopharmaceutical that is suitable for human use with this technology. We also describe a validated synthesis of [18F]FPEB with a commercial reactor-based system.
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Affiliation(s)
- Steven H Liang
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA, USA, 02114 ; Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - Daniel L Yokell
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - Raul N Jackson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - Peter A Rice
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - Ronald Callahan
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA, USA, 02114 ; Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - Keith A Johnson
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA, USA, 02114 ; Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
| | - David Alagille
- Molecular NeuroImaging, LLC, New Haven, CT, 06510 ; Institute for Neurodegenerative Disorders, New Haven, CT, 06510
| | - Gilles Tamagnan
- Molecular NeuroImaging, LLC, New Haven, CT, 06510 ; Institute for Neurodegenerative Disorders, New Haven, CT, 06510
| | - Thomas Lee Collier
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA, USA, 02114 ; Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114 ; Advion Inc., 10 Brown Road, Ithaca, NY, 14850
| | - Neil Vasdev
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, MA, USA, 02114 ; Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114
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