Molecular dynamics simulations of ${}^1$H NMR relaxation in Gd${}^{3+}$--aqua

Abstract

Atomistic molecular dynamics simulations are used to investigate ${}^1$H NMR $T_1$ relaxation of water from paramagnetic Gd${}^{3+}$ ions in solution at 25${}^{\circ }$C. Simulations of the $T_1$ relaxivity dispersion function $r_1$ computed from the Gd${}^{3+}$--${}^1$H dipole--dipole autocorrelation function agree within $\simeq 8$\% of measurements in the range $f_0\simeq$ 5 $\leftrightarrow$ 500 MHz, without any adjustable parameters in the interpretation of the simulations, and without any relaxation models. The simulation results are discussed in the context of the Solomon-Bloembergen-Morgan inner-sphere relaxation model, and the Hwang-Freed outer-sphere relaxation model. Below $f_0\lesssim$ 5 MHz, the simulation overestimates $r_1$ compared to measurements, which is used to estimate the zero-field electron-spin relaxation time. The simulations show potential for predicting $r_1$ at high frequencies in chelated Gd${}^{3+}$ contrast-agents used for clinical MRI.

References in corpus (1)

• Molecular Dynamics Simulations of NMR Relaxation and Diffusion of Bulk Hydrocarbons and Water