A.A. Martinos Center for Biomedical Imaging, Suite 2301, 149 13th Street, Charlestown, Massachusetts 02129, USA.
ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.
Nat Commun. 2017 Apr 26;8:15118. doi: 10.1038/ncomms15118.
Nanodiamonds are of interest as nontoxic substrates for targeted drug delivery and as highly biostable fluorescent markers for cellular tracking. Beyond optical techniques, however, options for noninvasive imaging of nanodiamonds in vivo are severely limited. Here, we demonstrate that the Overhauser effect, a proton-electron polarization transfer technique, can enable high-contrast magnetic resonance imaging (MRI) of nanodiamonds in water at room temperature and ultra-low magnetic field. The technique transfers spin polarization from paramagnetic impurities at nanodiamond surfaces to H spins in the surrounding water solution, creating MRI contrast on-demand. We examine the conditions required for maximum enhancement as well as the ultimate sensitivity of the technique. The ability to perform continuous in situ hyperpolarization via the Overhauser mechanism, in combination with the excellent in vivo stability of nanodiamond, raises the possibility of performing noninvasive in vivo tracking of nanodiamond over indefinitely long periods of time.
纳米金刚石作为靶向药物传递的无毒基底和细胞跟踪的高度稳定荧光标记物引起了人们的兴趣。然而，除了光学技术之外，体内纳米金刚石的非侵入性成像选择受到严重限制。在这里，我们证明了 Overhauser 效应，一种质子-电子极化转移技术，可以在室温下和超低磁场中实现水中纳米金刚石的高对比度磁共振成像 (MRI)。该技术将来自纳米金刚石表面的顺磁杂质的自旋极化转移到周围水溶液中的 H 自旋，按需创建 MRI 对比度。我们研究了实现最大增强所需的条件以及该技术的最终灵敏度。通过 Overhauser 机制进行连续原位极化的能力，结合纳米金刚石在体内的优异稳定性，使得在无限长的时间内对纳米金刚石进行非侵入性体内跟踪成为可能。
