Porous versus Dense ‐ Effect of Silica Coating on Contrast Enhancement of Iron Carbide Nanoparticles in T₂‐Weighted Magnetic Resonance Imaging

Abstract

Magnetic nanoparticles development is an intense subject in various biomedical applications. Among these applications, magnetic nanoparticles as contrast agents are of special interest for improving the diagnostic accuracy of magnetic resonance imaging (MRI). We report here the synthesis of magnetic iron carbide nanoparticles and their stabilization in aqueous media. The challenge of achieving phase transfer of hydrophobic iron carbide nanoparticles to hydrophilic media was addressed by silica shell. Silica coated iron carbide nanoparticles were fabricated with both mesoporous and dense silica shells followed by investigating the impact of such a coating on their performance as T 2 -negative contrast agents in MRI. The crystalline structure of silica coated iron carbide nanoparticles was confirmed via X-ray diffraction (XRD) analysis.Fourier transform infrared spectroscopy (FTIR) demonstrated formation of the silica coating and transmission electron microscopy (TEM) confirmed the core@shell morphology of silica coated iron carbide nanoparticles. Mesoporous and dense silica coated iron carbide nanoparticles exhibited high transverse relaxivity values of 457 and 365 mM À 1 s À 1 , respectively. The enhanced MRI efficiency obtained from the silica coated iron carbide nanoparticles highlights these core@shell structures as promising negative contrast agents. Based on the results, the nature of silica coating both in porous or dense forms has a significant effect on water relaxivity which makes the iron carbide@mesoporous silica nanoparticles highly efficient T 2 contrast agents.

The Effect of Surface Coating of Iron Oxide Nanoparticles on Magnetic Resonance Imaging Relaxivity

“…A nonlinear monoexponential equation I ∼M 0 •exp (-T E /T 2 ) was used to determine the T 2 relaxation time of each IONP sample (Ahmad et al, 2011). Finally, r 1 and r 2 values were calculated according to the linear relationship of longitudinal and transverse relaxation rates vs. iron concentration of IONPs (Hobson et al, 2019;Ahmadpoor et al, 2020).…”