Fig. 2. Room-temperature ODNP NMR of small biological molecules in H₂O at 9.4 T.

TEMPOL (100 mM) was used as the hyperpolarizing agent. The ODNP-enhanced ¹³C NMR spectra of U–¹³C serine (a), alanine (b), glycine (c), proline (d), and glucose (e) are scaled with the number of scans for visualizing directly the enhancement factor. All the microwave (mw)-off spectra in (a–e) are further scaled up by four-fold for the better visualization. The resolved ¹J_CH are showcased in spectral (d, e). f A positive trend of ODNP ¹³C enhancement over molar-free paramagnetic ¹³C NMR shift $\overline{{\delta }_{\mathrm{para}}}$ is visualized. The data on various molecules are presented in colors. The error of $\overline{{\delta }_{\mathrm{para}}}$ is defined as fitting error or standard deviation of $\overline{{\delta }_{\mathrm{para}}}$ values on carbons showing overlapping signals on ODNP spectra. The error of ODNP enhancement is determined from signal-to-noise ratio. More details about the error calculations can be found in “Methods”. Source data are provided as a Source Data file.