Kress Thomas, Che Kateryna, Epasto Ludovica M, Kozak Fanny, Negroni Mattia, Olsen Gregory L, Selimovic Albina, Kurzbach Dennis
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Faculty of Chemistry, Institute of Biological Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria.
Magn Reson (Gott). 2021 Jun 4;2(1):387-394. doi: 10.5194/mr-2-387-2021. eCollection 2021.
We present a system for facilitated sample vitrification, melting, and transfer in dissolution dynamic nuclear polarization (DDNP) experiments. In DDNP, a sample is typically hyperpolarized at cryogenic temperatures before dissolution with hot solvent and transfer to a nuclear magnetic resonance (NMR) spectrometer for detection in the liquid state. The resulting signal enhancements can exceed 4 orders of magnitude. However, the sudden temperature jump from cryogenic temperatures close to 1 K to ambient conditions imposes a particular challenge. It is necessary to rapidly melt the sample to avoid a prohibitively fast decay of hyperpolarization. Here, we demonstrate a sample dissolution method that facilitates the temperature jump by eliminating the need to open the cryostat used to cool the sample. This is achieved by inserting the sample through an airlock in combination with a dedicated dissolution system that is inserted through the same airlock shortly before the melting event. The advantages are threefold: (1) the cryostat can be operated continuously at low temperatures. (2) The melting process is rapid as no pressurization steps of the cryostat are required. (3) Blockages of the dissolution system due to freezing of solvents during melting and transfer are minimized.
我们展示了一种用于在溶解动态核极化（DDNP）实验中促进样品玻璃化、熔化和转移的系统。在DDNP中，样品通常在低温下进行超极化，然后用热溶剂溶解并转移到核磁共振（NMR）光谱仪中以在液态下进行检测。由此产生的信号增强可以超过4个数量级。然而，从接近1K的低温突然跃升至环境温度带来了特殊的挑战。必须快速熔化样品以避免超极化过快衰减。在此，我们展示了一种样品溶解方法，通过消除打开用于冷却样品的低温恒温器的需要来促进温度跃升。这是通过将样品通过气闸插入，并结合在熔化事件前不久通过同一气闸插入的专用溶解系统来实现的。优点有三个方面：（1）低温恒温器可以在低温下连续运行。（2）熔化过程迅速，因为不需要低温恒温器的加压步骤。（3）在熔化和转移过程中由于溶剂冻结导致的溶解系统堵塞被最小化。
