Interaction of Gd(III) MRI contrast agents with membranes: a review of recent EPR studies.
Interaction of Gd(III) MRI contrast agents with membranes: a review of recent EPR studies.
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Gd(III) MRI 造影剂与膜的相互作用：最近 EPR 研究的回顾。
DOI：
10.1007/bf02594601
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Clarkson,RB
中科院分区：
文献类型：
--
作者：
Smirnova,TI;Smirnov,AI;Belford,RL;Clarkson,RB
合理开发新的选择性顺磁性造影剂（PCA）需要详细了解它们与生物大分子的相互作用。这份报告显示了如何这些相互作用可以研究与电子顺磁共振（EPR）通过Gd 3+配合物与模型磷脂膜的相互作用的例子。结果表明，自旋标记EPR方法可用于检测：（i）亲脂性造影剂在模型膜中的存在和可能的位置，（ii）与PCA相互作用后膜组织的变化和扭曲，以及（iii）由于添加Gd 3+络合物而导致的双层局部极性及其相行为的变化。这项工作表明，Gd 3+复合物与磷脂双层的相互作用，可以直接观察到他们的连续波（CW）EPR光谱的变化，在高于X波段（9.5 GHz），其中所产生的信号从水和脂质结合的Gd 3+复合物成为解决的频率。EPR信号的有效因子的频率依赖性的分析提供了在生理条件下这些复合物的零场分裂（ZH）参数的估计以及关于该参数如何受与脂质的相互作用影响的信息。在高磁场下的多频EPR实验也有助于提供电子弛豫的频率色散的数据，主要是由这些高自旋离子的电子-电子偶极相互作用（EPR）的调制引起的。
Rational development of new selective paramagnetic contrast agents (PCAs) requires a detailed understanding of their interactions with biological macromolecules. This report shows how some of these interactions can be studied with electron paramagnetic resonance (EPR) through examples of Gd3+complexes interactions with model phospholipid membranes. It is shown that the spin label EPR method can be used to detect: (i) presence and possible location of lipophilic contrast agents in the model membranes, (ii) changes and distortions in membrane organization upon interaction with the PCAs, and (iii) changes in the local polarity of the bilayer and its phase behavior due to addition of Gd3+complexes. This work demonstrates that interaction of Gd3+complexes with phospholipid bilayers can be observed directly from changes in their continuous wave (CW) EPR spectra obtained at frequencies higher than X-band (9.5 GHz), where signals arising from aqueous and lipid-bound Gd3+complexes become resolved. Analysis of frequency dependence of the effectiveg-factors of the EPR signal provides estimates of zero-field splitting (ZFS) parameter for these complexes at physiological conditions and information on how this parameter is affected by interaction with lipids. Multifrequency EPR experiments at high magnetic fields are also useful in providing data on the frequency dispersion of electronic relaxation caused mainly by a modulation of the electron-electron dipolar interaction (ZFS) of these high spin ions.