Nitroxide-based triradical dopants for efficient low-temperature dynamic nuclear polarization in aqueous solutions...

Area of Science:

• Solid-state nuclear magnetic resonance (ssNMR)
• Dynamic nuclear polarization (DNP)

Background:

• Dynamic nuclear polarization (DNP) significantly enhances sensitivity in solid-state NMR (ssNMR) for frozen solutions.
• Nitroxide triradical compounds are effective DNP dopants, showing faster nuclear spin polarization build-up than biradicals.
• Previous DNP studies utilized triradicals for enhanced ssNMR.

Purpose of the Study:

• To synthesize and evaluate two new triradical compounds, sulfoacetyl-DOTOPA and PEG12-DOTOPA, for DNP-enhanced ssNMR.
• To assess the performance of these new dopants at 25 K and 9.41 T.
• To determine the solubility and applicability of these compounds in various biomolecular systems.

Main Methods:

• Synthesis of sulfoacetyl-DOTOPA and PEG12-DOTOPA.
• DNP-enhanced ssNMR experiments at 25 K and 9.41 T.
• Evaluation of signal enhancement and DNP build-up times.
• Assessment of compound solubility across a range of pH values and solvent mixtures.

Main Results:

• The new triradical compounds, sulfoacetyl-DOTOPA and PEG12-DOTOPA, demonstrated ssNMR signal enhancements and DNP build-up times comparable to existing triradical dopants.
• These compounds exhibit high solubility in aqueous buffers and water/glycerol mixtures.
• Solubility was confirmed at both acidic and basic pH values.

Conclusions:

• The newly synthesized triradical compounds are effective DNP dopants for ssNMR.
• Their high solubility and performance make them versatile tools for biomolecular studies using DNP-enhanced ssNMR.
• These compounds offer a valuable option for researchers seeking improved sensitivity in ssNMR experiments.