Ardenkjaer-Larsen Jan H, Fridlund Björn, Gram Andreas, Hansson Georg, Hansson Lennart, Lerche Mathilde H, Servin Rolf, Thaning Mikkel, Golman Klaes
Amersham Health Research and Development AB, Medeon, SE-205 12 Malmö, Sweden.
Proc Natl Acad Sci U S A. 2003 Sep 2;100(18):10158-63. doi: 10.1073/pnas.1733835100. Epub 2003 Aug 20.
A method for obtaining strongly polarized nuclear spins in solution has been developed. The method uses low temperature, high magnetic field, and dynamic nuclear polarization (DNP) to strongly polarize nuclear spins in the solid state. The solid sample is subsequently dissolved rapidly in a suitable solvent to create a solution of molecules with hyperpolarized nuclear spins. The polarization is performed in a DNP polarizer, consisting of a super-conducting magnet (3.35 T) and a liquid-helium cooled sample space. The sample is irradiated with microwaves at approximately 94 GHz. Subsequent to polarization, the sample is dissolved by an injection system inside the DNP magnet. The dissolution process effectively preserves the nuclear polarization. The resulting hyperpolarized liquid sample can be transferred to a high-resolution NMR spectrometer, where an enhanced NMR signal can be acquired, or it may be used as an agent for in vivo imaging or spectroscopy. In this article we describe the use of the method on aqueous solutions of [13C]urea. Polarizations of 37% for 13C and 7.8% for 15N, respectively, were obtained after the dissolution. These polarizations correspond to an enhancement of 44,400 for 13C and 23,500 for 15N, respectively, compared with thermal equilibrium at 9.4 T and room temperature. The method can be used generally for signal enhancement and reduction of measurement time in liquid-state NMR and opens up for a variety of in vitro and in vivo applications of DNP-enhanced NMR.
已开发出一种在溶液中获得强极化核自旋的方法。该方法利用低温、高磁场和动态核极化（DNP）使固态中的核自旋强烈极化。随后将固态样品迅速溶解在合适的溶剂中，以形成具有超极化核自旋的分子溶液。极化过程在一个DNP极化器中进行，该极化器由一个超导磁体（3.35 T）和一个液氦冷却的样品空间组成。样品用约94 GHz的微波进行辐照。极化后，样品通过DNP磁体内部的注射系统进行溶解。溶解过程有效地保留了核极化。所得的超极化液体样品可转移至高分辨率核磁共振光谱仪中，在那里可以获取增强的核磁共振信号，或者它可以用作体内成像或光谱分析的试剂。在本文中，我们描述了该方法在[13C]尿素水溶液中的应用。溶解后分别获得了13C为37%和15N为7.8%的极化率。与9.4 T和室温下的热平衡相比，这些极化率分别对应于13C增强了44400倍和15N增强了23500倍。该方法通常可用于增强液态核磁共振中的信号并减少测量时间，并为DNP增强核磁共振的各种体外和体内应用开辟了道路。
