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Technetium Chemistry at High Oxidation States: New Perspectives for Nanomaterials and Polyoxometalates in Medicine and Environmental Science

Applicant Braband Henrik
Number 126414
Funding scheme Ambizione
Research institution Institut für Chemie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Inorganic Chemistry
Start/End 01.10.2009 - 30.09.2012
Approved amount 388'791.00
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Keywords (7)

radiochemistry ; technetium; nanomaterials; polyoxometalates; nanomedicine; radiopharmaceutical chemistry; nuclear waste deposition

Lay Summary (English)

Lead
Lay summary
The aim of this project is to establish a center of competence for technetium chemistry focused on technetium (Tc) in higher oxidation states, to solve the emerging problems coming from the increasing production of the isotope 99Tc and to build a new strong future for technetium in medicine.

Techentium is the lightest chemical element with no stable isotope. The isotope 99Tc is a weak beta-emitter with a very long half life time of 2.13x10exp(5) years. It is formed as a byproduct in nuclear power plants and is a great problem for nuclear waste management, due to its high mobility. The meta stable nuclear isomer 99mTc is a gamma-emitter with a half life time of 6 h. These properties make it suitable for radiopharmaceutical applications and it is used today in over 80 % for standard radio diagnostics in medicine. Nevertheless, the number of young academics working on this important field is dramatically decreased in the last years. New impulses are needed to recall the importance of Tc chemistry and radiochemistry generally.

The combination of imaging with Tc and the so called nanomedicine, the application of nanotechnology to healthcare could have such an impact. The development of a stable, not air sensitive Tc system which can be specifically linked to a nanoparticle or bound irreversible to a macromolecule such as a polyoxometalate (discrete oxygen cluster anions of early transition-metals in their highest oxidation states) will create a new field of technetium chemistry with the potential to reactivate research efforts on this element in the future. To realize this idea collaboration between fundamental investigations with both isotops 99Tc and 99mTc, materials science and medicine is essential.

This research project will tackle scientific challenges from the most important fields for which technetium is essential and aims at putting the different topics on a common, molecular base. Namely, the chemistry of technetium oxygen complexes with technetium in higher oxidation states will be explored in its full range. Rather than developing for all fields different strategies and using different compounds, it is the incentive of this project to use the same molecular cores for applications which are apparently different but rely ultimately on the same chemical requirements, long term stability in water and well defined chemical environment. Last but not least, we expect to attract young students since, according to our experience, such interdisciplinary research problems are highly appreciated. Thus, the topics include a strong educational aspect which is urgently required due to a foreseeable lack of scientists with experience in radionuclide chemistry.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Combining Bifunctional Chelator with (3+2)-Cycloaddition Approaches: Synthesis of Dual-Function Technetium Complexes
Braband H, Imstepf S, Benz M, Spingler B, Alberto R (2012), Combining Bifunctional Chelator with (3+2)-Cycloaddition Approaches: Synthesis of Dual-Function Technetium Complexes, in INORGANIC CHEMISTRY, 51(7), 4051-4057.
Water Stable fac-{TcO3}+ Complexes – A New Field of Technetium Chemistry
Braband Henrik (2011), Water Stable fac-{TcO3}+ Complexes – A New Field of Technetium Chemistry, in CHIMIA, 65(10), 776-781.
fac-[TcO3(tacn)]+: AVersatile Precursor for the Labelling of Pharmacophores, Amino Acids and Carbohydrates through a New Ligand- Centred Labelling Strategy
Braband Henrik, Tooyama Yuji, Fox Thomas, Simms Ryan, Forbes John, Valliant John F., Alberto Roger (2011), fac-[TcO3(tacn)]+: AVersatile Precursor for the Labelling of Pharmacophores, Amino Acids and Carbohydrates through a New Ligand- Centred Labelling Strategy, in Chem. Eur. J., 17(46), 12967-12974.
Triazacyclohexane (tach) Complexes of High-Valent Rhenium: Syntheses of [(R(3)tach)ReO3](+) (R = -CH3, -CH2C6H5) and Its Substitution Reactions
Braband H, Imstepf S, Felber M, Spingler B, Alberto R (2010), Triazacyclohexane (tach) Complexes of High-Valent Rhenium: Syntheses of [(R(3)tach)ReO3](+) (R = -CH3, -CH2C6H5) and Its Substitution Reactions, in INORGANIC CHEMISTRY, 49(4), 1283-1285.

Collaboration

Group / person Country
Types of collaboration
Friedrich-Alexander-University Erlangen-Nuremberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
40th International Conference on Coordination Chemistry 09.09.2012 Valencia, Spain
Chemiedozententagung 05.03.2012 Freiburg, Germany
7th International Symposium on Technetium and Rhenium Science and Utilization 04.08.2011 Moscow, Russia
International Symposium on Technetium and other Radiometals in Chemistry and Medicine 08.09.2010 Bressanone, Italy


Associated projects

Number Title Start Funding scheme
143102 Technetium Chemistry at High Oxidation States: New Opportunities for the Development of Radiopharmaceuticals 01.10.2012 Ambizione
140665 N-Heterocyclic Carbenes as Stabilizing Ligands for High-Valent Technetium Chemistry 01.05.2012 Project funding (Div. I-III)

Abstract

Despite the great tasks for the future, the number of young academics working with technetium has steadily decreasing in the last years. Nuclear waste disposal and radio-imaging in medicine are the main driving forces for the research with this element. Both fields of research are essential for future achievements; nevertheless, the scientific output (publications) of the technetium community has decreased by around 40% in the last 11 years (CAS). The long-lived isotope 99Tc is a common component of waste from nuclear reactors, fuel production and reprocessing and has a potential hazard because of its long half-life (2.13·10exp(5) years). The metastable radionuclide 99mTc is the “working horse” for standard radio-imaging in medicine due to its appropriated radiation properties (gamma-emitter, E = 140 keV, half-life time = 6 h). The synthesis of new 99mTc compounds suitable for selective targeting (e.g. cancer) in diagnostics is the main aim of today’s research with this element. Despite some very interesting and innovative new approaches, no new 99mTc-tracer has been brought to FDA approval since 1999 for different reasons. This fact starts to slow down the research efforts with technetium. New impulses are needed to recall the importance of Tc chemistry.The new strategies presented in this proposal to link Tc complexes by a [3+2] cycloaddition specifically to a nanoparticle (nanomedicine) and to bind Tc complexes irreversibly to a macromolecule such as a polyoxometalate will create new fields of technetium chemistry with the potential to reactivate research efforts with this element in the future.Therefore, the whole project is divided into four objectives which are thematically interlinked. The first objective (New Labeling Strategies) deals with the unique feature of Tc trioxo complexes to undergo metal-mediated vicinal cis-dihydroxylation reaction (alkene-glycol interconversion) by [3+2] cycloaddition with alkenes. This feature will be used to develop a new labeling procedure for biomolecules via a novel BFC approach. In the second objective (Nanomedicine), the new labeling strategy will be used to develop functionalized nanoparticales suitable for diagnostics and therapy in this new field of medicine. In the third objective (Polyoxometalates in nuclear medicine), the chemistry of polyoxometalates with technetium will be investigated with a focus on the synthesis of a labeled bio-active polyoxometalates for new applications in medicine. The last objective (Defined technetium immobilization by matrices incorporation), will combine knowledge and results of objective one to three aiming at incorporating technetium permanently in a solid phase and to solve one of the essential problems of technetium disposal.Summarizing, to solve the emerging problems arising through the increasing production of 99Tc and to build a strong, new future for technetium in medicine, a center of competence for technetium chemistry should be established focusing on technetium in higher oxidation states.
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