Use of Wavelet Signals in Molecular Dynamics Simulations of paramagneticmaterials employed as potential spectroscopic probes

Abstract

Currently, the cancer is one of the biggest causes of death in the world, having as great difficulty the diagnosis in its initial phase. Among the techniques used in the cancer diagnosis, we can highlight the Magnetic Resonance Imaging (MRI). The MRI is an effective diagnostic method, which by means of the use of contrast agents (CAs) is able to locate tumors of various natures. The most used CAs are the Gd 3+ complexes, although they are very effective and very toxic to the organism. Thus, new CAs are being studied to replace the Gd 3+ complexes, among them superparamagnetic iron oxide nanoparticles (SPIONs) and the Ni 2+ complexes (paraCEST) stand out. The SPIONs and the paraCEST are able to change the relaxation time T 1 and T 2 of the water molecules of the organism. In this work, we studied the face 100 of various iron oxides (γ-Fe2O3 , δ-FeOOH, α-FeOOH, Fe2O3 and Fe 3O4 ) and the Ni 2+ complexes ([Ni(ACAC)2(H 2 O)2 ], [Ni(TEA)] 2+ ) coordinating with explicit water molecules, in order to obtain the hyperfine coupling constants (A iso ) of 1 H and 17 O atoms of the water molecules. We also present a new methodology for the selection of molecular dynamics (MD) calculations, OWSCA (Optimal Wavelet Signal Compression Algorithm). The theoretical results suggest that the iron oxides studied may be promising substitutes for classic CAs, based on Gd 3+ complexes. The OWSCA method is efficient and can be used to treat signals from different systems.