蛍光イメージングとMRIの両方で使えるイメージング材料を新たに開発 ー水に溶ける「光るラジカル」が二つのイメージング技術に応用できることを世界で初めて実証ー

2026-09-28 九州大学

（中央）開発した水溶性発光ラジカルの分子構造および概念図とそれを用いた（左）蛍光イメージング画像および（右）MRI画像

＜関連情報＞

• https://www.kyushu-u.ac.jp/ja/researches/view/1566
• https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.77710

蛍光/磁気共鳴デュアルモーダルイメージングプローブ用水溶性発光トリチルラジカル Water-Soluble Luminescent Trityl Radical for Fluorescence/Magnetic Resonance Dual-Modal Imaging Probe

Kosuke Anraku, Satoshi Okada, Akira Sumiyoshi, Kenshiro Matsuda, Kazuhiro Nakamura, Takuya Hosokai, Ken Albrecht
Advanced Science  published: 27 September 2026
DOI:https://doi.org/10.1002/advs.77710

ABSTRACT

Tris(2,4,6-trichlorophenyl)methyl (TTM) radicals are promising scaffolds for fluorescence imaging (FI) and magnetic resonance imaging (MRI) owing to their long-wavelength emission and intrinsic paramagnetism. Incorporating donor-acceptor (D-A) architectures into TTM radicals has been an established strategy to enhance the brightness and photostability of TTM radicals. However, conventional D-A-type TTM radicals exhibit strong charge-transfer (CT)-dominated emission that is easily quenched in water due to accelerated non-radiative decay known as the energy-gap law. Here, we report water-soluble TTM radicals (TTM-trisTP3B and TTM-trisTP9B) which exhibit hybridized locally excited and CT character through rational modulation of the donor units and their substitution positions. New radicals exhibited high photostability and deep-red emission with photoluminescence quantum yields of 1.4% (TTM-trisTP3B, 690 nm) and 1.1% (TTM-trisTP9B, 685 nm) in water. Their dual functionality as both fluorescent probes and MRI contrast agents was demonstrated. TTM-trisTP3B was taken up by living cells, localized near the cell nucleus, and showed fluorescence. The new radicals also provided a clear longitudinal relaxation time (T₁)-weighted MRI contrast. This work represents the first demonstration of trityl radical functioning as practical FI/MRI dual-modal imaging probes, establishing a molecular platform without any surfactants or metals in which the fluorophore and electron-spin source are unified.