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The Rigakubu News
The Rigakubu News, May. 2026
Research Student Communicates to Faculty >
Quantum Technology Enabled by Chemistry: Toward Ultra-High-Sensitivity MRI
Nobuhiro Yanai (Professor, Department of Chemistry)
This century has seen the onset of the Second Quantum Revolution,
and the development of various quantum technologies based on quantum mechanics is advancing worldwide.
One such technology is supernuclear polarization, which leads to higher sensitivity in MRI.
While light-induced hyperpolarization has the advantage of operating near room temperature,
the mainstream approach has been a physical method involving the orientation of large crystals relative to a magnetic field.
Using a chemical approach known as “molecular design,”
we have discovered a more practical hyperpolarization technique that does not require magnetic field orientation.
Applications that utilize the properties of quantum mechanics—namely, the development of quantum technologies—are advancing. Representative quantum technologies include quantum computers, quantum communication and cryptography, and quantum sensing. How can chemistry, which enables the design and creation of new materials, contribute to this quantum era?
One candidate is hyperpolarization, which can enhance the sensitivity of magnetic resonance imaging (MRI).MRI detects nuclear spins, such as 1H, possessed by molecules; however, at the magnetic field strengths used in medical settings, there are roughly equal numbers of up- and down-pointing nuclear spins, and because they cancel each other out, the sensitivity is extremely low.The technology that solves this problem is hyperpolarization, which uses electron spins to align the directions of nuclear spins.
In particular, triplet hyperpolarization is a method that can be driven even at relatively high temperatures near room temperature. Simply put, it involves exposing the sample to light and microwaves (such as those from a microwave oven) to create a hyperpolarized state.Specifically, dye molecules absorb light and enter a state known as a triplet, in which they possess an electron spin; by efficiently transferring the orientation of this electron spin (quantum state) to the nuclear spins via microwave irradiation, a supernuclear polarization state is generated in which the nuclear spins are aligned in a specific direction.
However, there was a major hurdle to applying this triplet hyperpolarization. It required creating large, centimeter-sized single crystals and orienting them with extreme precision relative to a magnetic field. Since only dye molecules aligned exactly with the direction of the magnetic field can transfer polarization to the nuclear spins, this is a physical approach that relies on aligning the orientation of the dye molecules.While this is possible in the laboratory, it is not practical in a clinical setting. Furthermore, the number of molecules that can be incorporated into a single crystal is limited, making it impossible to hyperpolarize the probe molecules necessary for disease diagnosis.
Therefore, as chemists, we discovered that by designing appropriate molecules, we could efficiently achieve triplet hyperpolarization without needing to align the molecules. We realized that fullerene—a ball-shaped molecule—possesses an electron spin that spreads throughout the entire molecule upon photoexcitation, allowing for polarization transfer to the nuclear spin even when the molecules are oriented randomly.However, because the ball-like structure undergoes deformation, the electron spin polarization is quickly lost, rendering the fullerene unusable in its original form. We therefore discovered that a disubstituted fullerene—selectively chemically modified at two sites to reduce its symmetry—is less prone to deformation and can maintain electron spin polarization for a longer period of time.using this for triplet hyperpolarization, we demonstrated a practical nuclear spin polarization exceeding 10%—the highest ever achieved with randomly oriented molecules.
This research is based on the control of molecular quantum states through meticulous molecular design and can be considered a prime example of quantum technology enabled by chemistry. It is expected that the chemistry of manufacturing will continue to give rise to new quantum technologies and, in the process, unlock new possibilities for chemistry.
The results of this study were published in K. Sakamoto et al., Nature Commun., 16, 10045 (2025).
High-Efficiency Triplet Hyperpolarization Using Fullerene Derivatives with Random Orientations Relative to a Magnetic Field