Department of Physics, Duke University, Durham, NC 27708, USA.
Department of Chemistry, Duke University, Durham, NC 27708, USA.
J Magn Reson. 2014 Feb;239:81-6. doi: 10.1016/j.jmr.2013.12.009. Epub 2014 Jan 3.
Long-lived disconnected eigenstates (for example, the singlet state in a system with two nearly equivalent carbons, or the singlet-singlet state in a system with two chemically equivalent carbons and two chemically equivalent hydrogens) hold the potential to drastically extend the lifetime of hyperpolarization in molecular tracers for in vivo magnetic resonance imaging (MRI). However, a first-principles calculation of the expected lifetime (and thus selection of potential imaging agents) is made very difficult because of the large variety of relevant intra- and intermolecular relaxation mechanisms. As a result, all previous measurements relied on costly and time consuming syntheses of (13)C labeled compounds. Here we show that it is possible to determine (13)C singlet state lifetimes by detecting the naturally abundant doubly-labeled species. This approach allows for rapid and low cost screening of potential molecular biomarkers bearing long-lived states.
长寿命去耦本征态（例如，在两个几乎等效的碳原子系统中的单重态，或在两个化学等效的碳原子和两个化学等效的氢原子系统中的单重态-单重态）有可能极大地延长用于体内磁共振成像（MRI）的分子示踪物的极化稳定性。然而，由于相关的分子内和分子间弛豫机制种类繁多，因此对预期寿命（从而对潜在成像剂的选择）进行第一性原理计算变得非常困难。结果，所有以前的测量都依赖于昂贵且耗时的（13）C 标记化合物的合成。在这里，我们展示了通过检测天然丰度的双标记物种来确定（13）C 单重态寿命的可能性。这种方法允许快速且低成本地筛选具有长寿命状态的潜在分子生物标志物。
