Integrative Modulation of Magnetic Resonance Transverse and Longitudinal Relaxivity in a Cell-Viable Bimagnetic Ensemble, γ-Fe₂O₃@ZnFe₂O₄

Abstract

The potential application of magnetic nanosystems as magnetic resonance imaging (MRI) contrast agents has been thoroughly investigated. This work seeks to attain robust MRIcontrast efficiency by designing an interacting landscape of a bimagnetic ensemble of zinc ferrite nanorods and maghemite nanoparticles, γ-Fe 2 O 3 @ZnFe 2 O 4 . Because of competing spin clusters and structural anisotropy triggered by isotropic γ-Fe 2 O 3 and anisotropic ZnFe 2 O 4 , γ-Fe 2 O 3 @ZnFe 2 O 4 undergoes the evolution of cluster spin-glass state as evident from the critical slowing down law. Such interacting γ-Fe 2 O 3 @ZnFe 2 O 4 with spin flipping of 1.2 × 10 −8 s and energy barrier of 8.2 × 10 −14 erg reflects enhanced MRI-contrast signal. Additionally, γ-Fe 2 O 3 @ ZnFe 2 O 4 is cell-viable to noncancerous HEK 293 cell-line and shows no pro-tumorigenic activity as observed in MDA-MB-231, an extremely aggressive triple-negative breast cancer cell line. As a result, γ-Fe 2 O 3 @ZnFe 2 O 4 is a feasible option for an MRI-contrast agent having longitudinal relaxivity, r 1 , of 0.46 s −1 mM −1 and transverse relaxivity, r 2 , of 15.94 s −1 mM −1 , together with r 2 /r 1 of 34.65 at 1.41 T up to a modest metal concentration of 0.1 mM. Hence, this study addresses an interacting isotropic/anisotropic framework with faster water proton decay in MR-relaxivity resulting in phantom signal amplification.

Interacting Trimagnetic Ensembles for Enhanced Magnetic Resonance Transverse Relaxivity

“…The exotic behavior of magnetic nanosystems (MNPs) has been recognized as an emerging platform in the domain of the water proton diffusion mechanism in magnetic resonance imaging (MRI) relaxivity augmentation. − The water proton diffusion around the ensembles is governed by the following three conditions: motional averaging regime (MAR) model, , static dephasing regime (SDR), and echo-limiting regime (ELR) − to understand the MR transverse relaxivity. The correlation between magnetization and transverse relaxivity of MNPs in the regime of MAR is partially recognized in complex cluster structures.…”