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Updated: Jul 17, 2026

15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
Published on: April 19, 2021
Aqueous urea as a model system for bi-exponential relaxation.
1Department of Biomedical Engineering, Vanderbilt University School of Engineering, Nashville, TN 37232-2310, USA.
Aqueous urea doped with contrast agents forms an adjustable two-component system. This model allows for a wide range of T2 relaxation times and signal fractions, useful in MRI research.
Area of Science:
- Magnetic Resonance Imaging
- Biophysics
Background:
- Contrast agents are crucial for MRI.
- Developing adjustable model systems is important for understanding relaxation mechanisms.
Purpose of the Study:
- To assess the utility of aqueous urea doped with inner- and outer-sphere relaxation agents.
- To establish an adjustable two-component model system for MRI research.
Main Methods:
- T2 relaxation times were measured in 12 molal urea mixtures at pH 7.0.
- Varying concentrations of manganese chloride (MnCl2) and Feridex (iron oxide nanoparticles) were used.
Main Results:
- Bi-exponential relaxation behavior was observed.
- Relaxation rates showed a bilinear relationship with MnCl2 and Feridex concentrations.
- Feridex exhibited similar relaxivities in urea and water, while MnCl2 was significantly more effective in water.
Conclusions:
- Aqueous urea doped with contrast agents functions as a tunable two-compartment model system.
- This system can produce diverse T2 values and signal fractions for MRI applications.
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