フラーレン誘導体が光誘起超核偏極に有用であることを発見～高感度化MRIへの応用に必要な実用化レベルの高偏極率を達成～

2025-12-04 東京大学

フラーレン誘導体による高効率なトリプレットDNP

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/10999/
• https://www.nature.com/articles/s41467-025-66211-y

ランダム配向における光核超分極の増強のための置換フラーレン Substituted Fullerenes for Enhanced Optical Nuclear Hyperpolarization in Random Orientations

Keita Sakamoto,Katsuki Miyokawa,Tomoyuki Hamachi,Haoxuan Zhang,Jiarui Song,Kenichiro Tateishi,Tomohiro Uesaka,Hiroshi Imahori,Yasuhiro Kobori,Yuki Kurashige & Nobuhiro Yanai
Nature Communications  Published:04 December 2025
DOI:https://doi.org/10.1038/s41467-025-66211-y

Abstract

Polarized electron spins in photoexcited triplet states enable dynamic nuclear polarization (DNP) to enhance magnetic resonance imaging (MRI) sensitivity. For a practical nuclear polarization of 10%, single crystals must be precisely oriented in a magnetic field to generate narrow electron spin resonance lines, which is not appropriate for actual medical applications. Here, substituted fullerenes as triplet polarizing agents enable ¹H polarizations above 10%, even for random molecular orientations. While they have not been used as polarizing agents for triplet-DNP because of electron spin relaxation via pseudo-rotation, we overcome this by chemical modification of two sites on C₆₀ fullerenes. Symmetry considerations reveal fullerenes that avoided pseudo-rotations. Di-substituted fullerenes are ideal polarizing agents with sharp linewidths and long relaxation times that enabled 14.2% ¹H polarization in randomly oriented orientations. Optimized polarizing agents represent a promising approach for ultra-sensitive MRI medical diagnostics without the need for DNP under cryogenic temperatures and severe orientation control.