Effects of Gadolinium on the Dynamic Nuclear Polarization of [15N3] Metronidazole

In this work, we studied the dynamic nuclear polarization (DNP) process of [15N3]metronidazole (MNZ), an FDA-approved antibiotic that achieved good polarization (~6%) with very short polarization build-up time constants (~12min). We used Electron Paramagnetic Resonance (EPR) spectroscopy to show that a sample of [15N3]MNZ + trityl AH111501 had narrower EPR linewidth and larger magnitude than AH111501 alone, indicating an efficient polarization transfer from the radical electrons to 15N and supporting our observations of fast DNP buildup. We also demonstrated that an addition of gadolinium-based compound to the [15N3]MNZ +AH111501 sample broadened the EPR spectrum and prolonged DNP buildup as observed.