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Stable isotope labeled compounds

Researcher: József-Zsolt Szücs-Balázs

Keywords: labeled compounds, custom isotopic labeling, 2H, 13C, 15N and 18O

Description

Isotopic labeling is the chemical process of highlighting a molecule by increasing the atomic concentration of 2H/13C/15N/18O in its structure, thus making it possible to easily detect the path of that substance in various physico-chemical and biological processes.

Isotopic labeling is carried out by three different methods:

  • The chemical conversion of raw materials (obtained from isotope separation) into different precursors used for more complex labeling. This process can be achieved through classical synthesis methods, such as converting nitric acid to ammonia using Dewarda alloy in a basic medium. Alternatively, heterogeneous catalysis can be utilized, for example, by converting carbon monoxide into carbon dioxide or methane with metal catalysts that are deposited on a porous support.
  • Custom isotope labeling involves a two-step process. In the first step, the most suitable synthetic route for obtaining the desired compound is identified, tested, and optimized using non-labeled reactants. In the second step, the synthesis is carried out with labeled substances, resulting in the personalized labeled compound.
  • Biosynthesis of labeled compounds. Biological cultures capable of incorporating isotopically labeled products such as 2H, 13C, and 15N into their metabolism can be developed. It is possible to explore how to utilize the enzymatic background (e.g., proteins) of these cultures. This approach could be particularly beneficial in targeting specific medical conditions by transitioning from a non-specific treatment strategy to a more focused one, specifically by emphasizing the molecular processes associated with metabolic diseases.

 Applications

The applications of isotope technologies include agronomy, biochemistry, biology, medicine, nutrition, nuclear physics, and environmental science.

  • Isotopes can be utilized to track the metabolism of nutrients labeled with 15N and 13C. Amino acids that are labeled with 15N and 13C are employed in studies of nitrogen and carbon metabolism, allowing researchers to determine the rate of protein synthesis in the human body.
  • Stable isotopes are utilized in medical investigations where radioisotopes are not suitable (e.g. in pregnant or breastfeeding women). Compounds labeled with stable isotopes like 10B, 7Li, 15N, 157Gd, and 91Zr can also be applied in energetic nuclear reactors. For instance, 15N (with a concentration of 99 at. %) is used in uranium nitride nuclear fuel to prevent the production of the radioactive isotope 14C.
  • Understanding the dynamics of inorganic nitrogen in relation to soil profiles is crucial for both agricultural practices and for assessing water pollutants. To gain insight into nitrogen dynamics, research in agriculture has utilized double ammonium nitrate labeled with 15N, specifically 15NH4NO3. When used as a fertilizer, this compound enables tracking its path within the plant, allowing researchers to detect it in the roots, stems, or leaves. The data obtained is more precise and selective, making it particularly valuable for specialized studies.
  • In nuclear resonance spectroscopy of organic compounds, the most commonly analyzed nuclei are 13C and 15N. The information extracted from NMR (nuclear magnetic resonance) spectra helps characterize the local atomic-scale structure and molecular dynamics of the substances studied.

 Infrastructure

  • Isotopically labeled compounds synthesis laboratory – The only 2H, 13C, 15N and 18O labeled compounds synthesis laboratory in the country operates within the institute. This organic and inorganic synthesis laboratory employs optimized technologies in combination with analytical control methods to meet user requirements effectively. The main objective of the research team is to develop specialized technologies for custom isotopic labeling services.
  • IsoPrime100 mass spectrometer – Allows the determination of isotopic concentration (up to 100%) in gaseous samples of CO, CO2, N2.
  • Shimadzu GC gas chromatograph – 2010 – Used for the determination of the content of a gas mixture in continuous flow, measuring the content of different components in a sample.
  •  StirLIN-1 liquid nitrogen production station – Produces 120 l/day of liquid nitrogen, 99% purity, used for the synthesis of labeled compounds.

Advantages

 There are certain situations where conventional methods fail to extract useful information. In such cases, employing isotopic techniques becomes essential.

 Using compounds labeled with stable isotopes of biogenic elements has distinct advantages over radioactive tracers, particularly due to the incompatibility of the latter with complex living biological systems.

 Most labeled inorganic compounds yield over 80%, and the methods we have developed are scalable.

 INCDTIM has a long-standing tradition of developing and implementing technologies for the separation of light stable isotopes. Currently, we are the only European manufacturer capable of enriching 13C isotopes up to 85%, and 15N isotopes up to 99%.

Estimated costs

The production of the 15N isotope is economically favorable only for yields in the order of tens of kg/year. The cost of stable isotope labeled compounds depends on:

the quantity and concentration of the isotopes used

the raw materials used in the synthesis

the degree of difficulty of the synthesis procedure

the time needed for synthesis

and is thus customized for each user.