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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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Cavaliere A, Probst KC, Paisey SJ, Marshall C, Dheere AKH, Aigbirhio F, McGuigan C, Westwell AD. Radiosynthesis of [ 18F]-Labelled Pro-Nucleotides (ProTides). Molecules 2020; 25:E704. [PMID: 32041321 PMCID: PMC7037993 DOI: 10.3390/molecules25030704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/25/2020] [Accepted: 02/01/2020] [Indexed: 12/31/2022] Open
Abstract
Phosphoramidate pro-nucleotides (ProTides) have revolutionized the field of anti-viral and anti-cancer nucleoside therapy, overcoming the major limitations of nucleoside therapies and achieving clinical and commercial success. Despite the translation of ProTide technology into the clinic, there remain unresolved in vivo pharmacokinetic and pharmacodynamic questions. Positron Emission Tomography (PET) imaging using [18F]-labelled model ProTides could directly address key mechanistic questions and predict response to ProTide therapy. Here we report the first radiochemical synthesis of [18F]ProTides as novel probes for PET imaging. As a proof of concept, two chemically distinct radiolabelled ProTides have been synthesized as models of 3'- and 2'-fluorinated ProTides following different radiosynthetic approaches. The 3'-[18F]FLT ProTide was obtained via a late stage [18F]fluorination in radiochemical yields (RCY) of 15-30% (n = 5, decay-corrected from end of bombardment (EoB)), with high radiochemical purities (97%) and molar activities of 56 GBq/μmol (total synthesis time of 130 min.). The 2'-[18F]FIAU ProTide was obtained via an early stage [18F]fluorination approach with an RCY of 1-5% (n = 7, decay-corrected from EoB), with high radiochemical purities (98%) and molar activities of 53 GBq/μmol (total synthesis time of 240 min).
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Affiliation(s)
- Alessandra Cavaliere
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK; (A.C.)
- Wales Research & Diagnostic Positron Emission Tomography Imaging Centre (PETIC), School of Medicine, Cardiff University, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, Wales, UK; (K.C.P.); (S.J.P.); (C.M.)
| | - Katrin C. Probst
- Wales Research & Diagnostic Positron Emission Tomography Imaging Centre (PETIC), School of Medicine, Cardiff University, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, Wales, UK; (K.C.P.); (S.J.P.); (C.M.)
| | - Stephen J. Paisey
- Wales Research & Diagnostic Positron Emission Tomography Imaging Centre (PETIC), School of Medicine, Cardiff University, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, Wales, UK; (K.C.P.); (S.J.P.); (C.M.)
| | - Christopher Marshall
- Wales Research & Diagnostic Positron Emission Tomography Imaging Centre (PETIC), School of Medicine, Cardiff University, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, Wales, UK; (K.C.P.); (S.J.P.); (C.M.)
| | - Abdul K. H. Dheere
- Wolfson Brain Imaging Centre and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (A.K.H.D.); (F.A.)
| | - Franklin Aigbirhio
- Wolfson Brain Imaging Centre and Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK; (A.K.H.D.); (F.A.)
| | - Christopher McGuigan
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK; (A.C.)
| | - Andrew D. Westwell
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK; (A.C.)
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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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Gangangari KK, Humm JL, Larson SM, Pillarsetty NVK. TMSOTf assisted synthesis of 2'-deoxy-2'-[18F]fluoro-β-D-arabinofuranosylcytosine ([18F]FAC). PLoS One 2018; 13:e0196784. [PMID: 29715301 PMCID: PMC5929562 DOI: 10.1371/journal.pone.0196784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 04/19/2018] [Indexed: 01/19/2023] Open
Abstract
[18F]FAC (2’-deoxy-2’-[18F]fluoro-β-D-arabinofuranosylcytosine, 1) is a versatile probe for imaging deoxycytidine kinase (dCK) expression levels in vivo. dCK is responsible for phosphorylation of deoxycytidine (dC, 2) and other nucleoside analogs, plays a key role in immune activation and has demonstrated to be one of the key enzymes in activating nucleoside based drugs including gemcitabine. Reported synthesis of [18F]FAC is high yielding but is quite challenging requiring bromination using HBr and careful drying of excess HBr which is critical for successful synthesis. Here in we report a simplified trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted synthesis of [18F]FAC eliminating the need of bromination and drying. [18F]FAC (β-anomer) was synthesized with average isolated decay corrected yield of 10.59 + 4.2% (n = 6) with radiochemical purity of >98% and total synthesis time of 158 + 19 min.
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Affiliation(s)
- Kishore K. Gangangari
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
- Department of Chemistry, Hunter College and PhD Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, United States of America
| | - John L. Humm
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
| | - Steven M. Larson
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
| | - Naga Vara Kishore Pillarsetty
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
- Department of Radiology, Weill Cornell Medical College, New York, NY, United States of America
- * E-mail:
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Production of diverse PET probes with limited resources: 24 18F-labeled compounds prepared with a single radiosynthesizer. Proc Natl Acad Sci U S A 2017; 114:11309-11314. [PMID: 29073049 DOI: 10.1073/pnas.1710466114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
New radiolabeled probes for positron-emission tomography (PET) are providing an ever-increasing ability to answer diverse research and clinical questions and to facilitate the discovery, development, and clinical use of drugs in patient care. Despite the high equipment and facility costs to produce PET probes, many radiopharmacies and radiochemistry laboratories use a dedicated radiosynthesizer to produce each probe, even if the equipment is idle much of the time, to avoid the challenges of reconfiguring the system fluidics to switch from one probe to another. To meet growing demand, more cost-efficient approaches are being developed, such as radiosynthesizers based on disposable "cassettes," that do not require reconfiguration to switch among probes. However, most cassette-based systems make sacrifices in synthesis complexity or tolerated reaction conditions, and some do not support custom programming, thereby limiting their generality. In contrast, the design of the ELIXYS FLEX/CHEM cassette-based synthesizer supports higher temperatures and pressures than other systems while also facilitating flexible synthesis development. In this paper, the syntheses of 24 known PET probes are adapted to this system to explore the possibility of using a single radiosynthesizer and hot cell for production of a diverse array of compounds with wide-ranging synthesis requirements, alongside synthesis development efforts. Most probes were produced with yields and synthesis times comparable to literature reports, and because hardware modification was unnecessary, it was convenient to frequently switch among probes based on demand. Although our facility supplies probes for preclinical imaging, the same workflow would be applicable in a clinical setting.
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Fluorinated nucleosides as an important class of anticancer and antiviral agents. Future Med Chem 2017; 9:1809-1833. [DOI: 10.4155/fmc-2017-0095] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Fluorine-containing nucleoside analogs (NAs) represent a significant class of the US FDA-approved chemotherapeutics widely used in the clinic. The incorporation of fluorine into drug-like agents modulates lipophilic, electronic and steric parameters, thus influencing pharmacodynamic and pharmacokinetic properties of drugs. Fluorine can block oxidative metabolism of drugs and the formation of undesired metabolites by changing H-bonding interactions. In this review, we focus our attention on chemical fluorination reagents and methods used in the NAs field, including positron emission tomography radiochemistry. We briefly discuss both the cellular biology and clinical properties of FDA-approved and fluorine-containing nucleoside/nucleotide analogs in development as well as common resistance mechanisms associated with their use. Finally, we emphasize pronucleotide strategies used to improve therapeutic outcome of NAs in the clinic.
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van der Born D, Pees A, Poot AJ, Orru RVA, Windhorst AD, Vugts DJ. Fluorine-18 labelled building blocks for PET tracer synthesis. Chem Soc Rev 2017; 46:4709-4773. [DOI: 10.1039/c6cs00492j] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review presents a comprehensive overview of the synthesis and application of fluorine-18 labelled building blocks since 2010.
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Affiliation(s)
- Dion van der Born
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Anna Pees
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Alex J. Poot
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Romano V. A. Orru
- Department of Chemistry and Pharmaceutical Sciences and Amsterdam Institute for Molecules
- Medicines & Systems (AIMMS)
- VU University Amsterdam
- Amsterdam
- The Netherlands
| | - Albert D. Windhorst
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Danielle J. Vugts
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
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Rotsch D, Brossard T, Bihmidine S, Ying W, Gaddam V, Harmata M, Robertson JD, Swyers M, Jurisson SS, Braun DM. Radiosynthesis of 6'-Deoxy-6'[18F]Fluorosucrose via Automated Synthesis and Its Utility to Study In Vivo Sucrose Transport in Maize (Zea mays) Leaves. PLoS One 2015; 10:e0128989. [PMID: 26024520 PMCID: PMC4449027 DOI: 10.1371/journal.pone.0128989] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 05/01/2015] [Indexed: 01/08/2023] Open
Abstract
Sugars produced from photosynthesis in leaves are transported through the phloem tissues within veins and delivered to non-photosynthetic organs, such as roots, stems, flowers, and seeds, to support their growth and/or storage of carbohydrates. However, because the phloem is located internally within the veins, it is difficult to access and to study the dynamics of sugar transport. Radioactive tracers have been extensively used to study vascular transport in plants and have provided great insights into transport dynamics. To better study sucrose partitioning in vivo, a novel radioactive analog of sucrose was synthesized through a completely chemical synthesis route by substituting fluorine-18 (half-life 110 min) at the 6' position to generate 6'-deoxy-6'[(18)F]fluorosucrose ((18)FS). This radiotracer was then used to compare sucrose transport between wild-type maize plants and mutant plants lacking the Sucrose transporter1 (Sut1) gene, which has been shown to function in sucrose phloem loading. Our results demonstrate that (18)FS is transported in vivo, with the wild-type plants showing a greater rate of transport down the leaf blade than the sut1 mutant plants. A similar transport pattern was also observed for universally labeled [U-(14)C]sucrose ([U-(14)C]suc). Our findings support the proposed sucrose phloem loading function of the Sut1 gene in maize, and additionally demonstrate that the (18)FS analog is a valuable, new tool that offers imaging advantages over [U-(14)C]suc for studying phloem transport in plants.
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Affiliation(s)
- David Rotsch
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Tom Brossard
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Saadia Bihmidine
- Division of Biological Sciences, Interdisciplinary Plant Group and the Missouri Maize Center, University of Missouri, Columbia, Missouri, United States of America
| | - Weijiang Ying
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Vikram Gaddam
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Michael Harmata
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - J. David Robertson
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
- University of Missouri Research Reactor, University of Missouri, Columbia, Missouri, United States of America
| | - Michael Swyers
- Division of Biological Sciences, Interdisciplinary Plant Group and the Missouri Maize Center, University of Missouri, Columbia, Missouri, United States of America
| | - Silvia S. Jurisson
- Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America
| | - David M. Braun
- Division of Biological Sciences, Interdisciplinary Plant Group and the Missouri Maize Center, University of Missouri, Columbia, Missouri, United States of America
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Gómez-Vallejo V, Gaja V, Gona KB, Llop J. Nitrogen-13: historical review and future perspectives. J Labelled Comp Radiopharm 2014; 57:244-54. [DOI: 10.1002/jlcr.3163] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/29/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Vanessa Gómez-Vallejo
- Radiochemistry Department, Molecular Imaging Unit; CIC biomaGUNE; Parque Tecnológico de Miramón; San Sebastián 20009 Guipúzcoa Spain
| | - Vijay Gaja
- Radiochemistry Department, Molecular Imaging Unit; CIC biomaGUNE; Parque Tecnológico de Miramón; San Sebastián 20009 Guipúzcoa Spain
| | - Kiran B. Gona
- Radiochemistry Department, Molecular Imaging Unit; CIC biomaGUNE; Parque Tecnológico de Miramón; San Sebastián 20009 Guipúzcoa Spain
| | - Jordi Llop
- Radiochemistry Department, Molecular Imaging Unit; CIC biomaGUNE; Parque Tecnológico de Miramón; San Sebastián 20009 Guipúzcoa Spain
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Tumor-specific targeting with modified Sindbis viral vectors: evaluation with optical imaging and positron emission tomography in vivo. Mol Imaging Biol 2013; 15:166-74. [PMID: 22847302 DOI: 10.1007/s11307-012-0585-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE Sindbis virus (SINV) infect tumor cells specifically and systemically throughout the body. Sindbis vectors are capable of expressing high levels of transduced suicide genes and thus efficiently produce enzymes for prodrug conversion in infected tumor cells. The ability to monitor suicide gene expression levels and viral load in patients, after administration of the vectors, would significantly enhance this tumor-specific therapeutic option. PROCEDURES The tumor specificity of SINV is mediated by the 67-kDa laminin receptor (LR). We probed different cancer cell lines for their LR expression and, to determine the specific role of LR-expression in the infection cycle, used different molecular imaging strategies, such as bioluminescence, fluorescence molecular tomography, and positron emission tomography, to evaluate SINV-mediated infection in vitro and in vivo. RESULTS All cancer cell lines showed a marked expression of LR. The infection rates of the SINV particles, however, differed significantly among the cell lines. CONCLUSION We used novel molecular imaging techniques to visualize vector delivery to different neoplatic cells. SINV infection rates proofed to be not solely dependent on cellular LR expression. Further studies need to evaluate the herein discussed ways of cellular infection and viral replication.
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Pascali G, Watts P, Salvadori PA. Microfluidics in radiopharmaceutical chemistry. Nucl Med Biol 2013; 40:776-87. [DOI: 10.1016/j.nucmedbio.2013.04.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/20/2013] [Accepted: 04/03/2013] [Indexed: 11/28/2022]
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Lazari M, Quinn KM, Claggett SB, Collins J, Shah GJ, Herman HE, Maraglia B, Phelps ME, Moore MD, van Dam RM. ELIXYS - a fully automated, three-reactor high-pressure radiosynthesizer for development and routine production of diverse PET tracers. EJNMMI Res 2013; 3:52. [PMID: 23849185 PMCID: PMC3717127 DOI: 10.1186/2191-219x-3-52] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 07/02/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Automated radiosynthesizers are vital for routine production of positron-emission tomography tracers to minimize radiation exposure to operators and to ensure reproducible synthesis yields. The recent trend in the synthesizer industry towards the use of disposable kits aims to simplify setup and operation for the user, but often introduces several limitations related to temperature and chemical compatibility, thus requiring reoptimization of protocols developed on non-cassette-based systems. Radiochemists would benefit from a single hybrid system that provides tremendous flexibility for development and optimization of reaction conditions while also providing a pathway to simple, cassette-based production of diverse tracers. METHODS We have designed, built, and tested an automated three-reactor radiosynthesizer (ELIXYS) to provide a flexible radiosynthesis platform suitable for both tracer development and routine production. The synthesizer is capable of performing high-pressure and high-temperature reactions by eliminating permanent tubing and valve connections to the reaction vessel. Each of the three movable reactors can seal against different locations on disposable cassettes to carry out different functions such as sealed reactions, evaporations, and reagent addition. A reagent and gas handling robot moves sealed reagent vials from storage locations in the cassette to addition positions and also dynamically provides vacuum and inert gas to ports on the cassette. The software integrates these automated features into chemistry unit operations (e.g., React, Evaporate, Add) to intuitively create synthesis protocols. 2-Deoxy-2-[18F]fluoro-5-methyl-β-l-arabinofuranosyluracil (l-[18F]FMAU) and 2-deoxy-2-[18F]fluoro-β-d-arabinofuranosylcytosine (d-[18F]FAC) were synthesized to validate the system. RESULTS l-[18F]FMAU and d-[18F]FAC were successfully synthesized in 165 and 170 min, respectively, with decay-corrected radiochemical yields of 46% ± 1% (n = 6) and 31% ± 5% (n = 6), respectively. The yield, repeatability, and synthesis time are comparable to, or better than, other reports. d-[18F]FAC produced by ELIXYS and another manually operated apparatus exhibited similar biodistribution in wild-type mice. CONCLUSION The ELIXYS automated radiosynthesizer is capable of performing radiosyntheses requiring demanding conditions: up to three reaction vessels, high temperatures, high pressures, and sensitive reagents. Such flexibility facilitates tracer development and the ability to synthesize multiple tracers on the same system without customization or replumbing. The disposable cassette approach simplifies the transition from development to production.
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Affiliation(s)
- Mark Lazari
- Department of Bioengineering, Henry Samueli School of Engineering, UCLA, Los Angeles, CA 90095, USA.
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Rensch C, Jackson A, Lindner S, Salvamoser R, Samper V, Riese S, Bartenstein P, Wängler C, Wängler B. Microfluidics: a groundbreaking technology for PET tracer production? Molecules 2013; 18:7930-56. [PMID: 23884128 PMCID: PMC6270045 DOI: 10.3390/molecules18077930] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 06/21/2013] [Accepted: 07/03/2013] [Indexed: 11/16/2022] Open
Abstract
Application of microfluidics to Positron Emission Tomography (PET) tracer synthesis has attracted increasing interest within the last decade. The technical advantages of microfluidics, in particular the high surface to volume ratio and resulting fast thermal heating and cooling rates of reagents can lead to reduced reaction times, increased synthesis yields and reduced by-products. In addition automated reaction optimization, reduced consumption of expensive reagents and a path towards a reduced system footprint have been successfully demonstrated. The processing of radioactivity levels required for routine production, use of microfluidic-produced PET tracer doses in preclinical and clinical imaging as well as feasibility studies on autoradiolytic decomposition have all given promising results. However, the number of microfluidic synthesizers utilized for commercial routine production of PET tracers is very limited. This study reviews the state of the art in microfluidic PET tracer synthesis, highlighting critical design aspects, strengths, weaknesses and presenting several characteristics of the diverse PET market space which are thought to have a significant impact on research, development and engineering of microfluidic devices in this field. Furthermore, the topics of batch- and single-dose production, cyclotron to quality control integration as well as centralized versus de-centralized market distribution models are addressed.
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Affiliation(s)
- Christian Rensch
- GE Global Research, Freisinger Landstrasse 50, Garching bei Munich 85748, Germany; E-Mails: (R.S.); (V.S.)
| | - Alexander Jackson
- GE Healthcare, Life Sciences, The Grove Centre, White Lion Rd., Amersham HP7 9LL, UK; E-Mails: (A.J.); (S.R.)
| | - Simon Lindner
- University Hospital Munich, Department of Nuclear Medicine, Ludwig Maximilians-University, Munich 81377, Germany; E-Mails: (S.L.); (P.B.); (C.W.)
| | - Ruben Salvamoser
- GE Global Research, Freisinger Landstrasse 50, Garching bei Munich 85748, Germany; E-Mails: (R.S.); (V.S.)
| | - Victor Samper
- GE Global Research, Freisinger Landstrasse 50, Garching bei Munich 85748, Germany; E-Mails: (R.S.); (V.S.)
| | - Stefan Riese
- GE Healthcare, Life Sciences, The Grove Centre, White Lion Rd., Amersham HP7 9LL, UK; E-Mails: (A.J.); (S.R.)
| | - Peter Bartenstein
- University Hospital Munich, Department of Nuclear Medicine, Ludwig Maximilians-University, Munich 81377, Germany; E-Mails: (S.L.); (P.B.); (C.W.)
| | - Carmen Wängler
- University Hospital Munich, Department of Nuclear Medicine, Ludwig Maximilians-University, Munich 81377, Germany; E-Mails: (S.L.); (P.B.); (C.W.)
- Biomedical Chemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim 68167, Germany
| | - Björn Wängler
- Molecular Imaging and Radiochemistry, Department of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim 68167, Germany
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Amaraesekera B, Marchis PD, Bobinski KP, Radu CG, Czernin J, Barrio JR, Michael van Dam R. High-pressure, compact, modular radiosynthesizer for production of positron emitting biomarkers. Appl Radiat Isot 2013; 78:88-101. [PMID: 23702794 DOI: 10.1016/j.apradiso.2013.04.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 03/10/2013] [Accepted: 04/13/2013] [Indexed: 11/17/2022]
Abstract
A robust, modular, semi-automated synthesis unit useful for conducting radiochemical reactions under pressurized conditions (up to ∼200psi [1.4MPa]) for the production of PET biomarkers has been developed. This compact unit (7.6cm×33.0cm×58.4cm) is capable of performing any single step reaction that is generally encountered in radiochemical syntheses, and multiple units can be combined for more complex syntheses. The versatility of a 3-unit system is exemplified by reliably conducting the multi-step syntheses of 2'-deoxy-2'-[(18)F]fluoro-1-β-arabinofuranosyl-uracil and -cytosine derivatives, which involve corrosive and moisture sensitive reagents under pressurized conditions.
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Affiliation(s)
- Bernard Amaraesekera
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Plug-and-play modules for flexible radiosynthesis. Appl Radiat Isot 2013; 78:113-24. [PMID: 23702795 DOI: 10.1016/j.apradiso.2013.04.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 03/23/2013] [Accepted: 04/13/2013] [Indexed: 11/23/2022]
Abstract
We present a plug-and-play radiosynthesis platform and accompanying computer software based on modular subunits that can easily and flexibly be configured to implement a diverse range of radiosynthesis protocols. Modules were developed that perform: (i) reagent storage and delivery, (ii) evaporations and sealed reactions, and (iii) cartridge-based purifications. The reaction module incorporates a simple robotic mechanism that removes tubing from the vessel and replaces it with a stopper prior to sealed reactions, enabling the system to withstand high pressures and thus provide tremendous flexibility in choice of solvents and temperatures. Any number of modules can rapidly be connected together using only a few fluidic connections to implement a particular synthesis, and the resulting system is controlled in a semi-automated fashion by a single software interface. Radiosyntheses of 2-[(18)F]fluoro-2-deoxy-d-glucose ([(18)F]FDG), 1-[(18)F]fluoro-4-nitrobenzene ([(18)F]FNB), and 2'-deoxy-2'-[(18)F]fluoro-1-β-d-arabinofuranosyl cytosine (d-[(18)F]FAC) were performed to validate the system and demonstrate its versatility.
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Alauddin MM. Nucleoside-based probes for imaging tumor proliferation using positron emission tomography. J Labelled Comp Radiopharm 2013; 56:237-43. [PMID: 24285330 DOI: 10.1002/jlcr.3003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 07/03/2012] [Accepted: 11/06/2012] [Indexed: 02/03/2023]
Abstract
Cancer is one of the leading causes of human death, and early detection can be beneficial for its timely therapy and management. For the early detection of cancer, positron emission tomography (PET) is more accurate and sensitive than other imaging modalities, such as computed tomography and magnetic resonance imaging. [(18) F]-Labeled fluorodeoxyglucose is the most useful PET probe in early detection of cancer; however, its nonspecific accumulation and consequent false-positive findings warrant the identification of other PET probes. Thymidine (TdR) and its analogs have been radiolabeled for PET imaging of cellular proliferation and DNA synthesis. Because of its in vivo instability, radiolabeled TdR has not been successful in PET imaging. However, some of its radiolabeled analogs have been developed for PET imaging of cellular proliferation and DNA synthesis. In this review, the radiochemistry and production of (11) C-TdR and (11) C/(18) F-labeled TdR analogs published to date are presented.
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Affiliation(s)
- Mian M Alauddin
- Department of Experimental Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Ribeiro Morais G, Falconer RA, Santos I. Carbohydrate-Based Molecules for Molecular Imaging in Nuclear Medicine. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201457] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Dewkar GK, Sundaresan G, Lamichhane N, Hirsch J, Thadigiri C, Collier T, Hartman MCT, Vaidyanthan G, Zweit J. Microfluidic radiosynthesis and biodistribution of [18F] 2-(5-fluoro-pentyl)-2-methyl malonic acid. J Labelled Comp Radiopharm 2013; 56:289-94. [DOI: 10.1002/jlcr.3016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 11/29/2012] [Accepted: 11/30/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Gajanan K. Dewkar
- Center for Molecular Imaging, Department of Radiology; Virginia Commonwealth University; Richmond; VA; 23298; USA
| | - Gobalakrishnan Sundaresan
- Center for Molecular Imaging, Department of Radiology; Virginia Commonwealth University; Richmond; VA; 23298; USA
| | - Narottam Lamichhane
- Center for Molecular Imaging, Department of Radiology; Virginia Commonwealth University; Richmond; VA; 23298; USA
| | - Jerry Hirsch
- Center for Molecular Imaging, Department of Radiology; Virginia Commonwealth University; Richmond; VA; 23298; USA
| | - Celina Thadigiri
- Center for Molecular Imaging, Department of Radiology; Virginia Commonwealth University; Richmond; VA; 23298; USA
| | | | | | - Ganesan Vaidyanthan
- Department of Radiology; Duke University School of Medicine; Durham; NC; 27710; USA
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Lebedev A, Miraghaie R, Kotta K, Ball CE, Zhang J, Buchsbaum MS, Kolb HC, Elizarov A. Batch-reactor microfluidic device: first human use of a microfluidically produced PET radiotracer. LAB ON A CHIP 2013; 13:136-45. [PMID: 23135409 PMCID: PMC3743669 DOI: 10.1039/c2lc40853h] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The very first microfluidic device used for the production of (18)F-labeled tracers for clinical research is reported along with the first human Positron Emission Tomography scan obtained with a microfluidically produced radiotracer. The system integrates all operations necessary for the transformation of [(18)F]fluoride in irradiated cyclotron target water to a dose of radiopharmaceutical suitable for use in clinical research. The key microfluidic technologies developed for the device are a fluoride concentration system and a microfluidic batch reactor assembly. Concentration of fluoride was achieved by means of absorption of the fluoride anion on a micro ion-exchange column (5 μL of resin) followed by release of the radioactivity with 45 μL of the release solution (95 ± 3% overall efficiency). The reactor assembly includes an injection-molded reactor chip and a transparent machined lid press-fitted together. The resulting 50 μL cavity has a unique shape designed to minimize losses of liquid during reactor filling and liquid evaporation. The cavity has 8 ports for gases and liquids, each equipped with a 2-way on-chip mechanical valve rated for pressure up to 20.68 bar (300 psi). The temperature is controlled by a thermoelectric heater capable of heating the reactor up to 180 °C from RT in 150 s. A camera captures live video of the processes in the reactor. HPLC-based purification and reformulation units are also integrated in the device. The system is based on "split-box architecture", with reagents loaded from outside of the radiation shielding. It can be installed either in a standard hot cell, or as a self-shielded unit. Along with a high level of integration and automation, split-box architecture allowed for multiple production runs without the user being exposed to radiation fields. The system was used to support clinical trials of [(18)F]fallypride, a neuroimaging radiopharmaceutical under IND Application #109,880.
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Affiliation(s)
- Artem Lebedev
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
| | - Reza Miraghaie
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
| | - Kishore Kotta
- Department of Radiology, University of California, San Diego, 11388 Sorrento Valley Road, Suit #100, San Diego, California, USA
| | - Carroll E. Ball
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
| | - Jianzhong Zhang
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
| | - Monte S. Buchsbaum
- Department of Radiology, University of California, San Diego, 11388 Sorrento Valley Road, Suit #100, San Diego, California, USA
- Department of Psychiatry, University of California, San Diego, USA
| | - Hartmuth C. Kolb
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
| | - Arkadij Elizarov
- Molecular Imaging Biomarker Research, Siemens Healthcare, 6100 Bristol Pkw, Culver City, California, USA. Fax: +1-310-568-9491; Tel: +1-310-864-1684
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20
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Zhang H, Cantorias MV, Pillarsetty N, Burnazi EM, Cai S, Lewis JS. An improved strategy for the synthesis of [¹⁸F]-labeled arabinofuranosyl nucleosides. Nucl Med Biol 2012; 39:1182-8. [PMID: 22819195 PMCID: PMC3517724 DOI: 10.1016/j.nucmedbio.2012.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 05/14/2012] [Accepted: 06/07/2012] [Indexed: 02/07/2023]
Abstract
The expression of the herpes simplex virus type-1 thymidine kinase (HSV1-tk) gene can be imaged efficaciously using a variety of 2'-[(18)F]fluoro-2'-deoxy-1-b-D-arabinofuranosyl-uracil derivatives [[(18)F]-FXAU, X=I(iodo), E(ethyl), and M(methyl)]. However, the application of these derivatives in clinical and translational studies has been impeded by their complicated and long syntheses (3-5h). To remedy these issues, in the study at hand we have investigated whether microwave or combined catalysts could facilitate the coupling reaction between sugar and nucleobase and, further, have probed the feasibility of establishing a novel approach for [(18)F]-FXAU synthesis. We have demonstrated that the rate of the trimethylsilyl trifluoromethanesulfonate (TMSOTf)-catalyzed coupling reaction between the 2-deoxy-sugar and uracil derivatives at 90 °C can be significantly accelerated by microwave-driven heating or by the addition of Lewis acid catalyst (SnCl(4)). Further, we have observed that the stability of the α- and β-anomers of [(18)F]-FXAU derivatives differs during the hydrolysis step. Using the microwave-driven heating approach, overall decay-corrected radiochemical yields of 19%-27% were achieved for [(18)F]-FXAU in 120min at a specific activity of >22MBq/nmol (595Ci/mmol). Ultimately, we believe that these high yielding syntheses of [(18)F]-FIAU, [(18)F]-FMAU and [(18)F]-FEAU will facilitate routine production for clinical applications.
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Affiliation(s)
- Hanwen Zhang
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Melchor V. Cantorias
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | | | - Eva M. Burnazi
- Cyclotron-Radiochemistry Core, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Shangde Cai
- Cyclotron-Radiochemistry Core, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Jason S. Lewis
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
- Cyclotron-Radiochemistry Core, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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Chen K, Li Z, Conti PS. Microwave-assisted one-pot radiosynthesis of 2′-deoxy-2′-[18F]fluoro-5-methyl-1-β-d-arabinofuranosyluracil ([18F]-FMAU). Nucl Med Biol 2012; 39:1019-25. [DOI: 10.1016/j.nucmedbio.2012.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Revised: 03/09/2012] [Accepted: 03/09/2012] [Indexed: 01/05/2023]
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Gaja V, Gómez-Vallejo V, Cuadrado-Tejedor M, Borrell JI, Llop J. Synthesis of 13N-labelled radiotracers by using microfluidic technology. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.2946] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Vijay Gaja
- Radiochemistry Department; CIC biomaGUNE; Paseo Miramón 182; San Sebastián; 20009; Spain
| | - Vanessa Gómez-Vallejo
- Radiochemistry Department; CIC biomaGUNE; Paseo Miramón 182; San Sebastián; 20009; Spain
| | | | - José I. Borrell
- Grup d'Enginyeria Molecular, Institut Químic de Sarrià; Universitat Ramon Llull; Via Augusta 390; 08017; Barcelona; Spain
| | - Jordi Llop
- Radiochemistry Department; CIC biomaGUNE; Paseo Miramón 182; San Sebastián; 20009; Spain
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Study of [18F]FLT and [123I]IaraU for cellular imaging in HSV1 tk-transfected murine fibrosarcoma cells: evaluation of the tracer uptake using 5-fluoro, 5-iodo and 5-iodovinyl arabinosyl uridines as competitive probes. Nucl Med Biol 2011; 39:371-6. [PMID: 22130503 DOI: 10.1016/j.nucmedbio.2011.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 09/08/2011] [Accepted: 09/15/2011] [Indexed: 11/21/2022]
Abstract
As one of the most intensively studied probes for imaging of the cellular proliferation, [(18)F]FLT was investigated whether the targeting specificity of thymidine kinase 1 (TK1) dependency could be enhanced through a synergistic effect mediated by herpes simplex type 1 virus (HSV1) tk gene in terms of the TK1 or TK2 expression. 5-[(123)I]Iodo arabinosyl uridine ([(123)I]IaraU) was prepared in a radiochemical yield of 8% and specific activity of 21 GBq/μmol, respectively. Inhibition of the cellular uptake of these two tracers was compared by using the arabinosyl uridine analogs such as 5-iodo, 5-fluoro and 5-(E)-iodovinyl arabinosyl uridine along with 2'-fluoro-5-iodo arabinosyl uridine (FIAU). Due to potential instability of the iodo group, accumulation index of 1.6 for [(123)I]IaraU by HSV1-TK vs. control cells could virtually be achieved at 1.5 h, but dropped to 0.2 compared to 2.0 for [(18)F]FLT at 5 h. The results from competitive inhibition by these nucleosides against the accumulation of [(18)F]FLT implied that FLT exerted a mixed TK1- and TK2-dependent inhibition with HSV1-tk gene transfection because of the shifting of thymidine kinase status. Taken together, the combination of [(18)F]FLT and HSV1-TK provides a synergistic imaging potency.
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De Leonardis F, Pascali G, Salvadori PA, Watts P, Pamme N. On-chip pre-concentration and complexation of [¹⁸F]fluoride ions via regenerable anion exchange particles for radiochemical synthesis of Positron Emission Tomography tracers. J Chromatogr A 2011; 1218:4714-9. [PMID: 21683956 DOI: 10.1016/j.chroma.2011.05.062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 10/18/2022]
Abstract
Microfluidic approaches have demonstrated a relevant impact on radiochemical reactions involving Positron Emission Tomography (PET) nuclides, due to shorter reaction times and smaller precursor quantities. However, little attention has been given to the integration of the initial pre-concentration and drying of radioactive [(18)F]fluoride ions, required for the labeling of radiotracer compounds. In this work we report the design, fabrication and implementation of a glass microfluidic device filled with recyclable anion exchange particles for the repeated recovery of [(18)F] and [(19)F]fluoride ions. The device was first tested with non radioactive [(19)F]fluoride ions and it was shown to repeatedly trap and elute >95% fluoride over 40 successive experimental runs with no decrease in efficiency. The same device was then tested for the trapping and release of [(18)F]fluoride ions over 20 experiments with no measurable decrease in performance. Finally, the [(18)F]fluoride ions were eluted as a K(18)F/K2.2.2 complex, dried by repeated dissolution in acetonitrile and evaporation of residual water, and reacted with ethyl ditosylate (EtDT) leading to the desired product ([(18)F]fluoroethyltosylate) with 96 ± 3% yield (RCY). The overall time needed for conditioning, trapping, elution and regeneration was less than 6 min. This approach will be of great benefit towards an integrated platform able to perform faster and safer radiochemical synthesis on the micro-scale.
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Cai H, Li Z, Conti PS. The improved syntheses of 5-substituted 2'-[18F]fluoro-2'-deoxy-arabinofuranosyluracil derivatives ([18F]FAU, [18F]FEAU, [18F]FFAU, [18F]FCAU, [18F]FBAU and [18F]FIAU) using a multistep one-pot strategy. Nucl Med Biol 2011; 38:659-66. [PMID: 21718941 DOI: 10.1016/j.nucmedbio.2011.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 12/28/2010] [Accepted: 01/01/2011] [Indexed: 10/18/2022]
Abstract
INTRODUCTION We and others have previously reported a four-step radiosynthesis of a series of 2'-deoxy-2'-[(18)F]fluoro-5-substituted-1-β-D-arabinofuranosyluracil derivatives including [(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU as thymidine derivatives for tumor proliferation and/or reporter gene expression imaging with positron emission tomography (PET). Although the radiosynthesis has been proven to be reproducible and efficient, this complicated multistep reaction is difficult to incorporate into an automated cGMP-compliant radiosynthesis module for routine production. Recently, we have developed a simple and efficient one-pot method for routine production of [(18)F]FMAU. In this study, we studied the feasibility of radiosynthesizing [(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU using this newly developed method. METHODS Similar to the radiosynthesis of [(18)F]FMAU, 5-substituted 2'-[(18)F]fluoro-2'-deoxy-arabinofuranosyluracil derivatives ([(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU) were synthesized in one-pot radiosynthesis module in the presence of Friedel-Crafts catalyst TMSOTf and HMDS. RESULTS This one-pot radiosynthesis method could be used to produce [(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU. The overall radiochemical yields of these tracers varied from 4.1%±0.8% to 10.1%±1.9% (decay-corrected, n=4). The overall reaction time was reduced from 210 min to 150 min from the end of bombardment, and the radiochemical purity was >99%. CONCLUSIONS The improved radiosyntheses of [(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU have been achieved with reasonable yields and high purity using a multistep one-pot method. The synthetic time has been reduced, and the reaction procedures have been significantly simplified. The success of this approach may make PET tracers [(18)F]FAU, [(18)F]FEAU, [(18)F]FFAU, [(18)F]FCAU, [(18)F]FBAU and [(18)F]FIAU more accessible for preclinical and clinical research.
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Affiliation(s)
- Hancheng Cai
- Department of Radiology, Molecular Imaging Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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