NMR relaxation and relaxivity parameters of MRI probes revealed by optimal wavelet signal compression of molecular dynamics simulations

Abstract

The MRI contrast agents (CAs) have been routinely used for detecting tumors at early stages. Currently, the most used CAs in MRI are gadolinium (Gd3+) complexes. However, these CAs can be toxic to the body. Thus, this work proposes Ni2+ complexes ([Ni(ACAC)2(H2O)2], [Ni(TEA)]2+) as promising CAs. For the theoretical prediction, molecular dynamics simulations were carried out and the conformations were selected by the optimal wavelet signal compression algorithm method. The T1 and T2 values were obtained directly by means of the spectral density. Our findings showed that the Ni2+ complexes can be promising CAs in MRI.

Chrysazin semiquinone radical anion. A theoretical study of the influence of the solvent on the electron spin resonance spectrum

“…This corresponds to a complete re-ordering of the relative magnitudes, consistent with the assignment of the 1 H constants measured in MeOH [9]. The 13 C and 17 O constants computed for the hydrogen-bonded cluster are given in S3 and S6, including also nuclear coordinates and NBO charges and spin populations. They indicate even more drastic rearrangements, particularly of the 13 C constants, with positive and negative shifts of several Gauss.…”

“…In the present investigation, the ability of modern theoretical solvation models to predict the hyperfine constants of C•‾ in liquid solution is investigated. Molecular dynamics simulation studies of the liquid state with explicit representation of hundreds or thousands of molecules are possible [13][14][15][16][17]. These studies allow the investigation of important thermal effects, but they are highly demanding in terms of theoretical knowhow and computational effort.…”

“…These studies allow the investigation of important thermal effects, but they are highly demanding in terms of theoretical knowhow and computational effort. We shall consider computationally more feasible static procedures with simulation of the influence of the solvent by Polarizable Continuum Models (PCM) 4 [15][16][17][18][19][20][21][22][23][24][25]. In particular, we shall explore applications of the Integral Equation Formalism Polarizable Continuum Model (IEFPCM) [21][22][23] and the Isodensity Polarizable Continuum Model (IPCM) [24,25].…”

“…The isotropic 1 H hyperfine coupling constants computed for the semiquinone C•‾ in the gas phase are listed in Table 1. Corresponding 13 C and 17 O constants are given in S3 and further details are provided in S5 with nuclear coordinates, NBO charges, and NBO spin populations. The predicted ordering of the methine proton constants is |a 3,6 | > |a 2,7 | > |a 4,5 | which is consistent with the assignments of the values measured in aprotic solvents like N,N-dimethylformamide (DMF) [9] and dimethylsulfoxide (DMSO) [10], as ultimately determined by Stegmann and associates [9].…”

“…The predicted ordering is consistent with the assignment of the constants measured in an aprotic solvent like DMF, but not with the assignment of those measured in MeOH (Table 1). Supplementary data for C•‾ in the solvents DMF and MeOH are provided in S3, S7, and S8, including 1 H, 13 C, and 17 O hyperfine data, nuclear coordinates, and NBO charges and spin populations.…”