Exploiting the Proton Exchange as an Additional Route to Enhance the Relaxivity of Paramagnetic MRI Contrast Agents
Exploiting the Proton Exchange as an Additional Route to Enhance the Relaxivity of Paramagnetic MRI Contrast Agents
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DOI：
10.1021/acs.inorgchem.8b00521
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发表时间：
2018-05-07
影响因子：
4.6
通讯作者：
Baranyai, Zsolt
中科院分区：
文献类型：
--
作者：
Aime, Silvio;Baroni, Simona;Baranyai, Zsolt
Gd（HP-DO 3A）的弛豫率作为pH值和缓冲液组成的函数进行了研究，以确定所观察到的弛豫增强的主要因素，由于交换的配位羟基质子。它是建立的顺磁弛豫时间，T，m，的配位羟基质子是约50%短于配位水分子中的质子。控制配体中配位的醇OH部分的pK是在生理/病理条件下利用质子交换增强弛豫率的基础。合成了一种新的Gd衍生物（HP-DO 3A），它是通过用CF 3取代CH 3基团而得到的。在这种复合物中，OH基团变得更加酸性。因此，质子交换对弛豫率的最大贡献被转移到具有氟化配体的较低pH区域。
The relaxivity of Gd(HP-DO3A) was studied as a function of pH and buffer composition in order to identify the main factors of the observed relaxation enhancement due to the exchange of the coordinated hydroxyl proton. It was established that the paramagnetic relaxation time, T,m, of the coordinated hydroxyl proton is about 50% shorter than that of the protons in the coordinated water molecule. The control of the pK of the coordinated alcoholic OH moiety in the ligand is fundamental to utilize the proton exchange enhanced relaxivity under physio/pathologic conditions. A new derivative of Gd(HP-DO3A) was synthesized by replacing the CH3 group with a CF3 moiety. In this complex, the OH group becomes more acidic. Consequently, the maximum contribution of the proton exchange to the relaxivity is shifted to a lower pH region with the fluorinated ligand.