Less risk, less costs: Portable spectroscopy devices could soon become real

 Magnetic resonance imaging, which is utilized in medicine for diagnostic purposes, is one of the many analytical applications of nuclear magnetic resonance (NMR). However, NMR's application is frequently constrained by the need to produce strong magnetic fields. By removing the requirement for strong magnetic fields, researchers have now found potential new ways to minimize the size of the corresponding devices as well as the potential risk associated with them. This is accomplished by coupling a unique hyperpolarization approach with so-called zero- to ultralow-field NMR.

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Magnetic resonance imaging, which is utilized in medicine for diagnostic purposes, is one of the many analytical applications of nuclear magnetic resonance (NMR). However, NMR's application is frequently constrained by the need to produce strong magnetic fields. Researchers at the Helmholtz Institute Mainz (HIM) and Johannes Gutenberg University Mainz (JGU) have now identified potential new approaches to decrease the size of the corresponding devices as well as the potential risk involved by doing away with the requirement for strong magnetic fields. This is accomplished by coupling a unique hyperpolarization approach with so-called zero- to ultralow-field NMR. "This cutting-edge approach is based on a ground-breaking idea. It offers up a new variety of prospects and overcomes past disadvantages," stated Dr. Danila Barskiy, a Sofja Kovalevskaja Award winner who has been working in the relevant discipline at JGU and HIM since 2020.

New approach to enable measurements without strong magnetic fields

Because of the magnets, the current generation of NMR apparatus is incredibly bulky and expensive. The current shortage of liquid helium used as a coolant is another complicating factor. Barskiy said, "With our new technique we are gradually moving ZULF NMR towards a status of being completely magnet-free, but we still have many challenges to overcome,"

Barskiy's concept of combining zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) with a unique method that allows for the hyperpolarization of atomic nuclei eliminates the need for magnets in this situation. Even ZULF NMR, a recently created type of spectroscopy, yields a wealth of analytical data without the use of strong magnetic fields. The ability of low-field NMR to detect signals in the presence of conductive materials, such as metals, gives it another benefit over high-field NMR. The sensors used for ZULF NMR are typically optically pumped magnetometers, which are highly sensitive, user-friendly, and already obtainable in the market. A ZULF NMR spectrometer can therefore be put together fairly easily.

SABRE-Relay: Transferring spin order like a baton

However, there is a problem to be solved with the generated NMR signal. Only a small number of compounds can be analyzed using the procedures that have been utilized up to now to generate the signal, and they also come with astronomical expenses. Barskiy has chosen to make use of the SABRE hyperpolarization technology, which enables the alignment of many nuclear spins in solution. There are several such methods that could generate a signal strong enough to be detected in ZULF circumstances. SABRE, which stands for Signal Amplification by Reversible Exchange, is one of them and has proven to be extremely effective. An iridium metal complex that facilitates the transfer of the spin order from parahydrogen to a substrate is essential to the SABRE method.

Barskiy has used SABRE-Relay, a relatively new advancement of the SABRE approach, to get over the drawbacks brought on by the sample's transient binding to the complex. In this instance, polarization is induced using SABRE and then transmitted to a secondary substrate.

Spin chemistry at the interface of physics and chemistry

Dr. Danila Barskiy, lead author Erik Van Dyke, and their co-authors describe how they were able to identify the signals for methanol and ethanol extracted from a sample of vodka in their article titled "Relayed Hyperpolarization for Zero-Field Nuclear Magnetic Resonance" published in Science Advances. According to Barskiy, "This simple example demonstrates how we have been able to extend the application range of ZULF NMR with the help of an inexpensive, rapid, and versatile method of hyperpolarization,"

"We hope that we've managed to get a little closer to our objective of making feasible the development of compact, portable devices that can be used for the analysis of liquids such as blood and urine and in future, possibly endowing discrimination of particular chemicals such as glucose and amino acids." the researchers wrote.

Danila Barskiy relocated from the University of California, Berkeley to Mainz after receiving a Sofja Kovalevskaja Award from the Alexander von Humboldt Foundation in 2020. He then started doing research in Professor Dmitry Budker's group at the JGU Institute of Physics and HIM. Physical chemist Barskiy is in charge of a team of researchers looking into potential uses of NMR in chemistry, biology, and medicine.

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Materials provided by Johannes Gutenberg Universitaet Mainz. Note: Content may be edited for style and length.