Stable Isotope Tracer Technology

Stable isotope tracer technology uses stable isotopic tracer atoms or compounds to study the movement and transformation principles of the substances being traced. This method measures the content of the same non-labeled compound by detecting the change of the isotope ratio and reflects the bioavailability and metabolism of the tracked substance in the organism.

Fundamental

Stable isotope tracer technology is mainly developed by using the characteristics of stable isotopes and their compounds. In nature, stable isotopes and their compounds have the same chemical and biological properties as the corresponding common elements and their compounds, but have different nuclear physical properties, which can be distinguished and detected. Therefore, stable isotopes can be used as indicators Trace atoms, and synthesize labeled compounds (such as labeled amino acids, labeled drugs, labeled proteins, etc.) to replace the corresponding non-labeled compounds. Using the different characteristics of labeled and unlabeled compounds, the position and quantity changes before and after the stable isotope reaction are determined by analytical instruments such as mass spectrometry and nuclear magnetic resonance, so as to clarify the mechanism, pathway and effect of the reaction.

Characteristics of Stable Isotope Tracer Technology

Stable isotopes are safe and non-radiative, and will not cause harm to animals and plants. There are no special protection requirements in the process of separation, synthesis of labeled compounds and application. This technology is convenient, and can be directly utilized in animal and human nutrition, clinical medical research and medical diagnosis. The half-lives of stable isotopes are all greater than 1×10¹⁵ years, which is not limited by the research time. The physical properties are stable, and the signal value of stable isotopes will not decay with time.

Stable isotopes allow simultaneous determination of different mass numbers, so different isotopes of the same element or isotopes of different elements can be simultaneously determined, thereby improving experimental efficiency.

With the development of separation technology, stable isotopes are showing wide sources. For example, stable isotopes such as ¹³C, ¹⁵N and ¹⁸O can be produced economically by cryogenic distillation and chemical exchange methods.

The detection methods of stable isotopes have been greatly developed. Both mass spectrometry and nuclear magnetic resonance have been improved to increase the sensitivity. Moreover, the operation is very simple and accurate, which promotes the wide applications of stable isotopes.

Main Application Fields of Stable Isotope Tracer Technology

1. The Field of Agricultural Research
   Nitrogen is one of the essential nutrients for plant growth and development, and an important component of plant protein. It directly or indirectly affects the metabolic activities and growth and development of plants in many aspects, so the application of ¹⁵N in agricultural science is very extensive, including improving nitrogen fertilizer efficiency, improving varieties, animal nutrition metabolism, biological nitrogen fixation, feed formulation, etc. For instances, ¹⁵N tracer technology has been applied to study the whereabouts of nitrogen fertilizers, the factors affecting nitrogen utilization, and scientific fertilization of organic and inorganic fertilizers.
2. Application in the Fields of Medicine and Life Sciences
   Stable isotope products have been widely used in the medical field, for the diagnosis and identification of various diseases, efficacy evaluation, organ function research and new drug development. For example, positron emission tomography (PET) technology uses ¹⁸O-water as a tracer imaging agent, which can display the activities of biomolecular metabolism, receptors and neural mediators in vivo, and can diagnose diseases earlier, sensitively and accurately, especially for tumors, coronary heart disease and brain disease. A breath test with the isotope ¹³C urea can detect Helicobacter pylori in the gastric epithelium. The method accurately determines the Helicobacter pylori by detecting the ¹³C/12C isotope ratio in the exhaled gas of the patient after oral administration of ¹³C urea. In addition, in the research of drug metabolism, ¹³C, ¹⁵N, ¹⁸O are applicable for isotope labeling, so as to further trace the research. In addition, in the research of drug metabolism, with ¹³C, ¹⁵N, and ¹⁸O isotope tracer techonolgoy, it is possible to explore the metabolic pathways of drugs in the body, which is of great significance for the development of new drugs and the guidance of drug use. Stable isotope amino acid organically labeled compounds have unique tracer effect, which makes them of great significance in the study of protein structure by nuclear magnetic resonance spectroscopy.
3. Energy metabolism
   Research on energy metabolism is an area of increasing attention. The research on energy metabolism of organisms is to measure the production of carbon oxides in animals and humans using double isotopes, that is ¹⁸O combined with deuterium. By using this indirect calorimetry, the energy metabolism of the whole organism can be estimated from carbon oxide production. Currently, energy metabolism research focuses on sports medicine, children's nutrition, weight loss, astronaut diet, etc.