Proton magnetization relaxation in aqueous suspensions of composite silicon-iron nanoparticles for biomedical applications

Abstract

Silicon-iron composite nanoparticles produced by arc-discharge plasma ablation method were characterized by scanning electron microscopy, dynamic light scattering, X-ray fluorescence diffractometry, and the effect of iron content and size of the nanoparticles on hydrogen nuclei magnetization relaxation were investigated by nuclear magnetic resonance relaxometry. It was shown that increasing in iron content during the synthesis leads to distortion of the spherical shape of the nanoparticles and increasing of their mean sizes from 140 nm to 350 nm. Nonlinear dependence of the longitudinal and transverse relaxivities from iron content was demonstrated. Increase in the iron concentration above 2.5 at. % leads to reduction of the both relaxivities, which can be explained by nonuniform distribution of iron and formation of iron containing agglomerates. It was shown that transverse and longitudinal relaxivities of the nanoparticles in their aqueous solutions inversely proportional from their hydrodynamic diameters in the range of 100 – 300 nm. The possibilities of using composite silicon-iron nanoparticles for biomedical applications are discussed.