Proton Hyperpolarization Relay from Nanocrystals to Liquid Water
Proton Hyperpolarization Relay from Nanocrystals to Liquid Water
复制标题
从纳米晶体到液态水的质子超极化中继
DOI：
10.1021/jacs.2c07518
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发表时间：
2022
影响因子：
15
通讯作者：
Yanai Nobuhiro
中科院分区：
文献类型：
--
作者：
Matsumoto Naoto;Nishimura Koki;Kimizuka Nobuo;Nishiyama Yusuke;Tateishi Kenichiro;Uesaka Tomohiro;Yanai Nobuhiro
利用光激发产生的瞬时电子自旋极化的动态核极化可以提高核磁共振的灵敏度，远远超过热平衡极限，用于生命科学和药物开发的分析。然而，室温下液态水的DNP仍然是一个重要的挑战。在这里，我们提出了一种称为超极化继电器的新方法，在该方法中，电子自旋的非平衡极化被转移到纳米晶体中的质子自旋，然后转移到大块水中的质子自旋。通过再沉淀法在控制纳米晶尺寸的同时，合成了掺杂了偏振剂的分子纳米晶，产生了高度偏振的光激发三重态。重复激光和微波辐射的三重态DNP序列增强了大块水和纳米晶体的核磁共振信号。纳米晶的尺寸越小，由于比表面积的增加，从纳米晶到水的极化转移的效率就越高。基于所罗门方程的一系列控制实验和仿真证实了超极化继电机制。
Dynamic nuclear polarization (DNP) using transient electron spin polarization generated by photoexcitation can improve nuclear magnetic resonance (NMR) sensitivity far beyond the thermal equilibrium limit for analysis in life science and drug discovery. However, DNP of liquid water at room temperature remains an important challenge. Here, we propose a new method called hyperpolarization relay, in which the nonequilibrium polarization of electron spins is transferred to proton spins in the nanocrystals and then to proton spins in bulk water. Molecular nanocrystals doped with a polarizing agent that generates a highly polarized photoexcited triplet are synthesized by a reprecipitation method while controlling the size of the nanocrystals. The triplet-DNP sequence of repeated laser and microwave irradiation enhances the NMR signal of bulk water as well as nanocrystals. The smaller size of the nanocrystals increases the efficiency of polarization transfer from the nanocrystals to water due to the increased surface area. A series of control experiments and simulations based on Solomon equations confirmed the hyperpolarization relay mechanism.