Positron Emission Tomography (PET) plays a major role in the early detection of various types of cancer. A research group led by Professor Katsumi Kaneko specially appointed of the Research Initiative for Supra-Substances (RISM), Shinshu University has found a way to separate oxygen-18 from oxygen-16, an essential isotope for PET diagnosis, high speed and high efficiency. The results of this research were recently published online in the journal Nature Communication.
The new method for quickly and efficiently separating O-18 from O2-16, which is abundant in the atmosphere, was made with nanoporous carbon, which is made with pores smaller than 1 nanometer. When a mixture of O2-16 and O2-18 is incorporated into the nanoporous carbon, the O2-18 is favorably adsorbed and effectively separated from O2-16. Experimental separation of O2-18 from O2-16 was also performed using the low-temperature waste heat from a natural gas storage facility.
O-18s play a key role in the early detection of cancer. Taking advantage of the property of cancer cells that take up much more glucose than normal cells, doctors inject a drug called 18F-FDG (fluorodeoxyglucose), which is an index of glucose metabolism and will using a PET device to clarify which part of the body is cancerous. 18F-FDG is a drug containing fluorine-18 (18F), which releases advanced electricity, bound to glucose. 18F-FDG is produced by nuclear reactivation in which O-18 is introduced before the proteins are injected.
Thus, O-18 is an important material that is not necessary for PET diagnosis but was difficult to obtain as O-18 contains only 0.2% of naturally occurring oxygen. To separate O-18 from most of the O-16 found in the atmosphere, it was necessary to extract O-18 from O-16, even though they have very similar boiling points. This distillery required precision technology and took over 6 months to complete.
The novel method using nanoporous carbon for O-18 distillation can be used not only for PET diagnosis but for research on depression, and this novel method can be applied in the separation of carbon isotopes and nitrogen, and other molecules useful for isotopic examination methods and therapeutic cancer drugs. The organization expects more demand for this method and content in the future.
Two co-authors of the international collaborative study submitted comments for the press release:
Professor Yury Gogotsi Drexel, USA
It is encouraging to see that my guest professorship at Shinshu University allowed me to participate in this important multi-institutional project that resulted in a new process for the separation of oxygen isotopes using developed carbon nanomaterials. in my laboratory at Drexel University.
Professor Karl Johnson of the University of Pittsburgh, USA
Working on this research project with Professor Kaneko, Professor Gogotsi, their teams, and others was an interesting and challenging experience. The experimental work was remarkable and actually pushed the limits of our theoretical capabilities to find out how quantum effects could be so important for relatively heavy isotopes.
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Magazine Reference:
Ujjain, SK, et al. (2021) Adsorption separation of heavier isotope gases in subnanometer carbon pores. Nature Communication. doi.org/10.1038/s41467-020-20744-6.