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Gower-Fry L, Wängler C, Bartenstein P, Beyer L, Lindner S, Jurkschat K, Wängler B, Bailey JJ, Schirrmacher R. Silicon-Fluoride Acceptors (SiFA) for 18F-Radiolabeling: From Bench to Bedside. Methods Mol Biol 2024; 2729:29-43. [PMID: 38006489 DOI: 10.1007/978-1-0716-3499-8_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Fluorine-18 (18F) is undoubtedly one of the most frequently applied radionuclides for the development of new radiotracers for positron emission tomography (PET) in the context of clinical cancer, neurological, and metabolic imaging. Until recently, the available radiochemical methodologies to introduce 18F into organic molecules ranging from small- to medium- and large-sized compounds were limited to a few applicable protocols. With the advent of late-stage fluorination of small aromatic, nonactivated compounds and various noncanonical labeling strategies geared toward the labeling of peptides and proteins, the molecular toolbox for PET radiotracer development was substantially extended. Especially, the noncanonical labeling methodologies characterized by the formation of Si-18F, B-18F, and Al-18F bonds give access to kit-like 18F-labeling of complex and side-group unprotected compounds, some of them already in clinical use. This chapter will particularly focus on silicon-fluoride acceptor (SiFA) chemistry and cover the history of its conceptual design and its translation into the clinical practice.
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Affiliation(s)
- Lexi Gower-Fry
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB, Canada
| | - Carmen Wängler
- Biomedical Chemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Leonie Beyer
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Klaus Jurkschat
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Dortmund, Germany
| | - Björn Wängler
- Molecular Imaging and Radiochemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany
| | - Justin J Bailey
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB, Canada
| | - Ralf Schirrmacher
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB, Canada.
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Gower-Fry L, Kronemann T, Dorian A, Pu Y, Jaworski C, Wängler C, Bartenstein P, Beyer L, Lindner S, Jurkschat K, Wängler B, Bailey JJ, Schirrmacher R. Recent Advances in the Clinical Translation of Silicon Fluoride Acceptor (SiFA) 18F-Radiopharmaceuticals. Pharmaceuticals (Basel) 2021; 14:ph14070701. [PMID: 34358127 PMCID: PMC8309031 DOI: 10.3390/ph14070701] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/15/2021] [Accepted: 07/17/2021] [Indexed: 12/20/2022] Open
Abstract
The incorporation of silicon fluoride acceptor (SiFA) moieties into a variety of molecules, such as peptides, proteins and biologically relevant small molecules, has improved the generation of 18F-radiopharmaceuticals for medical imaging. The efficient isotopic exchange radiofluorination process, in combination with the enhanced [18F]SiFA in vivo stability, make it a suitable strategy for fluorine-18 incorporation. This review will highlight the clinical applicability of [18F]SiFA-labeled compounds and discuss the significant radiotracers currently in clinical use.
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Affiliation(s)
- Lexi Gower-Fry
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Travis Kronemann
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Andreas Dorian
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Yinglan Pu
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Carolin Jaworski
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Carmen Wängler
- Biomedical Chemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany;
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, Marchioninistraße 15, 81377 Munich, Germany; (P.B.); (L.B.); (S.L.)
| | - Leonie Beyer
- Department of Nuclear Medicine, University Hospital, LMU Munich, Marchioninistraße 15, 81377 Munich, Germany; (P.B.); (L.B.); (S.L.)
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital, LMU Munich, Marchioninistraße 15, 81377 Munich, Germany; (P.B.); (L.B.); (S.L.)
| | - Klaus Jurkschat
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, 44227 Dortmund, Germany;
| | - Björn Wängler
- Molecular Imaging and Radiochemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany;
| | - Justin J. Bailey
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
| | - Ralf Schirrmacher
- Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB T6G 1Z2, Canada; (L.G.-F.); (T.K.); (A.D.); (Y.P.); (C.J.); (J.J.B.)
- Correspondence:
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Otaru S, Niemikoski H, Sarparanta M, Airaksinen AJ. Metabolism of a Bioorthogonal PET Tracer Candidate [ 19F/ 18F]SiFA-Tetrazine in Mouse Liver Microsomes: Biotransformation Pathways and Defluorination Investigated by UHPLC-HRMS. Mol Pharm 2020; 17:3106-3115. [PMID: 32539414 PMCID: PMC7497667 DOI: 10.1021/acs.molpharmaceut.0c00523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
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Organofluorosilicon based 18F-radiolabeling is an efficient
method for incorporating fluorine-18 into 18F-radiopharmaceuticals
for positron emission tomography (PET) by 19F/18F isotopic exchange (IE). The first PET radiopharmaceutical, 18F-SiFAlin-TATE, radiolabeled with a silicon-based
[18F]fluoride acceptor (SiFA), namely, a para-substituted
di-tert-butyl[18F]fluorosilylbenzene,
has entered clinical trials, and is paving the way for other potential
[18F]SiFA-labeled radiopharmaceuticals for diagnostic use.
In this study, we report the in vitro metabolism
of an oxime-linked SiFA tetrazine (SiFA–Tz), a new PET-radiotracer
candidate, recently evaluated for pretargeted PET imaging and macromolecule
labeling. Metabolism of SiFA–Tz was studied in mouse liver
microsomes (MLM) for elucidating its major biotransformation pathways.
Nontargeted screening by ultrahigh performance liquid chromatography
high-resolution mass spectrometry (UHPLC-HRMS) was utilized for detection
of unknown metabolites. The oxime bond between the SiFA and Tz groups
forms two geometric (E/Z) isomers,
which underwent the same biotransformations, but unexpectedly with
different kinetics. In total, nine proposed metabolites of SiFA–Tz
from phase I and II reactions were detected, five of which were defluorinated
in MLMs, elucidating the metabolic pathway leading to previously reported
defluorination of [18F]SiFA–Tz in vivo. Based on the HRMS studies a biotransformation pathway is proposed:
hydroxylation (+O) to tert-butyl group adjacent to
the silicon, followed by oxidative defluorination (+OH/-F) cleaving
the fluorine off the silicon. Interestingly, eight proposed metabolites
of a reduced dihydrotetrazine analogue, SiFA–H2Tz,
from phase I and II reactions were additionally detected. To the best
of our knowledge, this is the first reported comprehensive investigation
of enzyme mediated metabolic pathway of tetrazines and para-substituted
di-tert-butylfluorosilylbenzene fluoride acceptors,
providing novel structural information on the biotransformation and
fragmentation patterns of radiotracers bearing these structural motifs.
By investigating the metabolism preceding defluorination, structurally
optimized new SiFA compounds can be designed for expanding the portfolio
of efficient 19F/18F isotopic exchange labeling
probes for PET imaging.
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Affiliation(s)
- Sofia Otaru
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Hanna Niemikoski
- Finnish Institute for Verification of the Chemical Weapons Convention (VERIFIN), Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Mirkka Sarparanta
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland
| | - Anu J Airaksinen
- Radiochemistry, Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland.,Turku PET Centre, Department of Chemistry, University of Turku, 20500 Turku, Finland
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Wei H, Li Y, Wang S, Tao G, Wang T, Cheng S, Yang S, Ding Y. Side-chain-type imidazolium-functionalized anion exchange membranes: The effects of additional hydrophobic side chains and their hydrophobicity. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2019.02.058] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Li Y, Zhang J, Yang H, Yang S, Lu S, Wei H, Ding Y. Boosting the performance of an anion exchange membrane by the formation of well-connected ion conducting channels. Polym Chem 2019. [DOI: 10.1039/c9py00011a] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Enlarging the discrepancies between hydrophilic/hydrophobic segments in the chemical structure of an ionomer proved to be an efficient strategy to induce the formation of a microphase-separated morphology of the resulting anion exchange membrane.
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Affiliation(s)
- Yan Li
- School of Chemistry and Chemical Engineering
- Anhui Key Laboratory of Advanced Functional Materials and Devices
- Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering
- Hefei University of Technology
- Hefei 230009
| | - Jujia Zhang
- Beijing Key Laboratory of Bio-inspired Energy Materials and Devices
- School of Space and Environment
- Beihang University
- Beijing 100191
- China
| | - Hua Yang
- School of Chemistry and Chemical Engineering
- Anhui Key Laboratory of Advanced Functional Materials and Devices
- Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering
- Hefei University of Technology
- Hefei 230009
| | - Shanzhong Yang
- School of Chemistry and Chemical Engineering
- Anhui Key Laboratory of Advanced Functional Materials and Devices
- Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering
- Hefei University of Technology
- Hefei 230009
| | - Shanfu Lu
- Beijing Key Laboratory of Bio-inspired Energy Materials and Devices
- School of Space and Environment
- Beihang University
- Beijing 100191
- China
| | - Haibing Wei
- School of Chemistry and Chemical Engineering
- Anhui Key Laboratory of Advanced Functional Materials and Devices
- Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering
- Hefei University of Technology
- Hefei 230009
| | - Yunsheng Ding
- School of Chemistry and Chemical Engineering
- Anhui Key Laboratory of Advanced Functional Materials and Devices
- Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering
- Hefei University of Technology
- Hefei 230009
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Berke S, Kampmann AL, Wuest M, Bailey JJ, Glowacki B, Wuest F, Jurkschat K, Weberskirch R, Schirrmacher R. 18F-Radiolabeling and In Vivo Analysis of SiFA-Derivatized Polymeric Core–Shell Nanoparticles. Bioconjug Chem 2017; 29:89-95. [DOI: 10.1021/acs.bioconjchem.7b00630] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sheldon Berke
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
| | - Anne-Larissa Kampmann
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
| | - Melinda Wuest
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
| | - Justin J. Bailey
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
| | | | - Frank Wuest
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
| | | | | | - Ralf Schirrmacher
- Department
of Oncology, University of Alberta, 6820 116 Street, Edmonton, Alberta T6G 2R3, Canada
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Shi H, Wang Z, Huang C, Gu X, Jia T, Zhang A, Wu Z, Zhu L, Luo X, Zhao X, Jia N, Miao F. A Functional CT Contrast Agent for In Vivo Imaging of Tumor Hypoxia. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:3995-4006. [PMID: 27345304 DOI: 10.1002/smll.201601029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/23/2016] [Indexed: 05/16/2023]
Abstract
Hypoxia, which has been well established as a key feature of the tumor microenvironment, significantly influences tumor behavior and treatment response. Therefore, imaging for tumor hypoxia in vivo is warranted. Although some imaging modalities for detecting tumor hypoxia have been developed, such as magnetic resonance imaging, positron emission tomography, and optical imaging, these technologies still have their own specific limitations. As computed tomography (CT) is one of the most useful imaging tools in terms of availability, efficiency, and convenience, the feasibility of using a hypoxia-sensitive nanoprobe (Au@BSA-NHA) for CT imaging of tumor hypoxia is investigated, with emphasis on identifying different levels of hypoxia in two xenografts. The nanoprobe is composed of Au nanoparticles and nitroimidazole moiety which can be electively reduced by nitroreductase under hypoxic condition. In vitro, Au@BSA-NHA attain the higher cellular uptake under hypoxic condition. Attractively, after in vivo administration, Au@BSA-NHA can not only monitor the tumor hypoxic environment with CT enhancement but also detect the hypoxic status by the degree of enhancement in two xenograft tumors with different hypoxic levels. The results demonstrate that Au@BSA-NHA may potentially be used as a sensitive CT imaging agent for detecting tumor hypoxia.
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Affiliation(s)
- Hongyuan Shi
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
| | - Zhiming Wang
- The Education Ministry Key Laboratory of Resource Chemistry, Department of Chemistry, Life and Environmental Science College, Shanghai Normal University, No.100, Guilin Road, Shanghai, 200234, P. R. China
| | - Chusen Huang
- The Education Ministry Key Laboratory of Resource Chemistry, Department of Chemistry, Life and Environmental Science College, Shanghai Normal University, No.100, Guilin Road, Shanghai, 200234, P. R. China
| | - Xiaoli Gu
- Department of Radiology, Jing'an District Center Hospital, No.259, Xikang Road, Shanghai, 200040, P. R. China
| | - Ti Jia
- The Education Ministry Key Laboratory of Resource Chemistry, Department of Chemistry, Life and Environmental Science College, Shanghai Normal University, No.100, Guilin Road, Shanghai, 200234, P. R. China
| | - Amin Zhang
- The Education Ministry Key Laboratory of Resource Chemistry, Department of Chemistry, Life and Environmental Science College, Shanghai Normal University, No.100, Guilin Road, Shanghai, 200234, P. R. China
| | - Zhiyuan Wu
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
| | - Lan Zhu
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
| | - Xianfu Luo
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
| | - Xuesong Zhao
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
| | - Nengqin Jia
- The Education Ministry Key Laboratory of Resource Chemistry, Department of Chemistry, Life and Environmental Science College, Shanghai Normal University, No.100, Guilin Road, Shanghai, 200234, P. R. China
| | - Fei Miao
- Department of Radiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197, RuiJin 2nd Road, Shanghai, 200025, P. R. China
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Bernard-Gauthier V, Bailey JJ, Liu Z, Wängler B, Wängler C, Jurkschat K, Perrin DM, Schirrmacher R. From Unorthodox to Established: The Current Status of (18)F-Trifluoroborate- and (18)F-SiFA-Based Radiopharmaceuticals in PET Nuclear Imaging. Bioconjug Chem 2015; 27:267-79. [PMID: 26566577 DOI: 10.1021/acs.bioconjchem.5b00560] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Unorthodox (18)F-labeling strategies not employing the formation of a carbon-(18)F bond are seldom found in radiochemistry. Historically, the formation of a boron- or silicon-(18)F bond has been introduced very early on into the repertoire of labeling chemistries, but is without translation into any clinical radiotracer besides inorganic B[(18)F]F4(-) for brain tumor diagnosis. For many decades these labeling methodologies were forgotten and have just recently been revived by a handful of researchers thinking outside the box. When breaking with established paradigms such as the inability to obtain labeled compounds of high specific activity via isotopic exchange or performing radiofluorination in aqueous media, the research community often reacts skeptically. In 2005 and 2006, two novel labeling methodologies were introduced into radiochemistry for positron emission tomography (PET) tracer development: RBF3(-) labeling reported by Perrin et al. and the SiFA methodology by Schirrmacher, Jurkschat, and Waengler et al. which is based on isotopic exchange (IE). Both labeling methodologies have been complemented by other noncanonical strategies to introduce (18)F into biomolecules of diagnostic importance, thus profoundly enriching the landscape of (18)F radiolabeling. B- and Si-based labeling strategies finally revealed that IE is a viable alternative to established and traditional radiochemistry with the advantage of simplifying both the labeling effort as well as the necessary purification of the radiotracer. Hence IE will be the focus of this contribution over other noncanonical labeling methods. Peptides for tumor imaging especially lend themselves favorably toward one-step labeling via IE, but small molecules have been described as well, taking advantage of these new approaches, and have been used successfully for brain imaging. This Review gives an account of both radiochemistries centered on boron and silicon, describing the very beginnings of their basic research, the path that led to optimization of their chemistries, and the first encouraging preclinical results paving the way to their clinical use. This side by side approach will give the reader the opportunity to follow the development of a new basic discovery into a clinically applicable radiotracer including all the hurdles that have had to be overcome.
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Affiliation(s)
- Vadim Bernard-Gauthier
- Division of Oncological Imaging, Department of Oncology, University of Alberta , 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Justin J Bailey
- Division of Oncological Imaging, Department of Oncology, University of Alberta , 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Zhibo Liu
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health , 9000 Rockville Pike, Bethesda, Maryland 20892, United States
| | | | | | - Klaus Jurkschat
- Department of Chemistry and Chemical Biology, Technical University of Dortmund , 44227 Dortmund, Germany
| | - David M Perrin
- Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Ralf Schirrmacher
- Division of Oncological Imaging, Department of Oncology, University of Alberta , 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
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Chansaenpak K, Vabre B, Gabbaï FP. [(18)F]-Group 13 fluoride derivatives as radiotracers for positron emission tomography. Chem Soc Rev 2015; 45:954-71. [PMID: 26548467 DOI: 10.1039/c5cs00687b] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The field of (18)F chemistry is rapidly expanding because of the use of this radionuclide in radiotracers for positron emission tomography (PET). Until recently, most [(18)F]-radiotracers were generated by the direct attachment of (18)F to a carbon in the organic backbone of the radiotracer. The past decade has witnessed the emergence of a new strategy based on the formation of an (18)F-group 13 element bond. This approach, which is rooted in the field of fluoride anion complexation/coordination chemistry, has led to the development of a remarkable family of boron, aluminium and gallium [(18)F]-fluoride anion complexing agents which can be conjugated with peptides and small molecules to generate disease specific PET radiotracers. This review is dedicated to the chemistry of these group 13 [(18)F]-fluorides anion complexing agents and their use in PET. Some of the key fluoride-binding motifs covered in this review include the trifluoroborate unit bound to neutral or cationic electron deficient backbones, the BF2 unit of BODIPY dyes, and AlF or GaF3 units coordinated to multidentate Lewis basic ligands. In addition to describing how these moieties can be converted into their [(18)F]-analogs, this review also dicusses their incorporation into bioconjugates for application in PET.
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Affiliation(s)
- Kantapat Chansaenpak
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA.
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¹⁸F-labeled silicon-based fluoride acceptors: potential opportunities for novel positron emitting radiopharmaceuticals. BIOMED RESEARCH INTERNATIONAL 2014; 2014:454503. [PMID: 25157357 PMCID: PMC4135131 DOI: 10.1155/2014/454503] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/07/2014] [Accepted: 04/08/2014] [Indexed: 12/16/2022]
Abstract
BACKGROUND Over the recent years, radiopharmaceutical chemistry has experienced a wide variety of innovative pushes towards finding both novel and unconventional radiochemical methods to introduce fluorine-18 into radiotracers for positron emission tomography (PET). These "nonclassical" labeling methodologies based on silicon-, boron-, and aluminium-(18)F chemistry deviate from commonplace bonding of an [(18)F]fluorine atom ((18)F) to either an aliphatic or aromatic carbon atom. One method in particular, the silicon-fluoride-acceptor isotopic exchange (SiFA-IE) approach, invalidates a dogma in radiochemistry that has been widely accepted for many years: the inability to obtain radiopharmaceuticals of high specific activity (SA) via simple IE. METHODOLOGY The most advantageous feature of IE labeling in general is that labeling precursor and labeled radiotracer are chemically identical, eliminating the need to separate the radiotracer from its precursor. SiFA-IE chemistry proceeds in dipolar aprotic solvents at room temperature and below, entirely avoiding the formation of radioactive side products during the IE. SCOPE OF REVIEW A great plethora of different SiFA species have been reported in the literature ranging from small prosthetic groups and other compounds of low molecular weight to labeled peptides and most recently affibody molecules. CONCLUSIONS The literature over the last years (from 2006 to 2014) shows unambiguously that SiFA-IE and other silicon-based fluoride acceptor strategies relying on (18)F(-) leaving group substitutions have the potential to become a valuable addition to radiochemistry.
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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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