「放射化イメージング」でマウス体内の金ナノ粒子を可視化～がん治療薬の長期的な動態イメージングに向けて～

2025-03-13

2025-03-13 早稲田大学

早稲田大学大学院先進理工学研究科の越川七星氏と片岡淳教授らの研究チームは、大阪大学および京都大学の研究者と共同で、金ナノ粒子を直接可視化する「放射化イメージング」を開発し、マウス体内での金ナノ粒子の分布を可視化することに成功しました。この技術により、がん治療薬の長期的な体内動態の追跡が可能となり、治療効果の向上や副作用の軽減が期待されます。

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多様な薬物可視化のための金ナノ粒子の活性化イメージング: 生体内での実証
Activation imaging of gold nanoparticles for versatile drug visualization: An in vivo demonstration

N. Koshikawa;Y. Kikuchi;K. S. Tanaka;K. Tokoi;A. Mitsukai;H. Aoto;Y. Kadonaga;A. Toyoshima;H. Kato;K. Ooe;K. Takamiya;J. Kataoka
Applied Physics Letters Published:March 12 2025
DOI:https://doi.org/10.1063/5.0251048

Gold nanoparticles (AuNPs) have recently attracted considerable attention as promising drug carriers. In vivo imaging of AuNPs is required to investigate their pharmacokinetics. However, a direct and highly sensitive method has not yet been established. Therefore, we proposed the activation imaging of AuNPs that radioactivates AuNPs and non-invasively visualizes them using the emitted gamma rays. When the stable isotope of gold, ¹⁹⁷Au⁠, is irradiated with low-energy neutrons, it changes to radioactive ¹⁹⁸Au⁠, which predominantly emits 412-keV gamma rays. In this study, we synthesized [¹⁹⁸Au]AuNPs through neutron irradiation and intratumorally injected them into tumor-bearing mice. In vivo imaging was performed using wideband x rays and gamma rays imager, and the distribution of [¹⁹⁸Au]AuNPs in the body of mice was observed. Furthermore, we labeled the alpha-emitting therapeutic drug ²¹¹At with [¹⁹⁸Au]AuNPs⁠. Although ²¹¹At itself can be visualized using its 79-keV x rays, the long-term tracking of ²¹¹At-labeled AuNPs has been challenging due to its relatively short half-life of 7.2 h. The activation of AuNPs enables the long-term tracking of ²¹¹At-labeled AuNPs owing to the 2.7-day half-life of ¹⁹⁸Au⁠. ²¹¹At-labeled [¹⁹⁸Au]AuNPs were injected intravenously into mice and visualized using a wideband x rays and gamma rays imager. Simultaneous imaging of ²¹¹At and ¹⁹⁸Au was performed on the day of injection and 2 days after injection. Although ²¹¹At could no longer be imaged 2 days after injection, the distribution of the drug was visualized using gamma rays from ¹⁹⁸Au⁠.