One-thousand-fold enhancement of high field liquid nuclear magnetic resonance signals at room temperature

Nuclear magnetic resonance (NMR) is a fundamental spectroscopic technique for the study of biological systems and materials, molecular imaging and the analysis of small molecules. It detects interactions at very low energies and is thus non-invasive and applicable to a variety of targets, including animals and humans. However, one of its most severe limitations is its low sensitivity, which stems from the small interaction energies involved. Here, we report that dynamic nuclear polarization in liquid solution and at room temperature can enhance the NMR signal of C-13 nuclei by up to three orders of magnitude at magnetic fields of similar to 3 T. The experiment can be repeated within seconds for signal averaging, without interfering with the sample magnetic homogeneity. The method is therefore compatible with the conditions required for high-resolution NMR. Enhancement of C-13 signals on various organic compounds opens up new perspectives for dynamic nuclear polarization as a general tool to increase the sensitivity of liquid NMR.