The effect of¹³C enrichment in the glassing matrix on dynamic nuclear polarization of [1-¹³C]pyruvate

Dimethyl sulfoxide (DMSO) can effectively form a glassy matrix necessary for dynamic nuclear polarization (DNP) experiments. We tested the effects of (13)C enrichment in DMSO on DNP of [1-(13)C]pyruvate doped with trityl radical OX063Me. We found that the polarization build-up time τ of pyruvate in (13)C-labeled DMSO glassing solution is twice as fast as the unenriched DMSO while the nuclear magnetic resonance enhancement was unchanged. This indicates that (13)C-(13)C spin diffusion is a limiting factor in the kinetics of DNP in this system, but it has a minimal effect on the absolute value of polarization achievable for the target.