Iron Oxide Nanoparticles Produced by a Low-Energy Nd: YAG Laser Ablation Technique and Their Application as Contrast Agent for Magnetic Resonance Imaging

Abstract

A magnetic resonance imaging contrast agent is proposed using iron oxide nanoparticles (IONPs) synthesized by a pulsed laser ablation technique. Experimentally, an Nd: YAG laser (1064 nm, 7 ns, 30 mJ) was directed and focused on a high-purity iron plate immersed in a liquid solution of deionized water and polyvinylpyrrolidone (PVP). After a few minutes of laser bombardment, iron oxide nanoparticles dispersed in the liquid were homogeneously produced. A reddish yellow color-colloidal IONPs are produced in the water, while its color changes to dark brown for the PVP solution. The characterization results demonstrated that IONPs in the form of Fe2O3 and Fe3O4 made in the PVP have an excellent dispersibility with a spherical shape that is significantly smaller than that of IONPs made in the deionized water at the same laser repetition rate. The produced IONPs are further applied as a contrast agent for the magnetic resonance imaging (MRI) modality by varying concentrations from 0.05 mM to 2.31 mM. The results demonstrated that images of the IONPs sample with a concentration of 2.31 mM showed the highest contrast enhancement (Cenh), with an enhancement factor of 221.875 % for T1-weighted images and 91.227 % for T2-weighted images. IONPs with a concentration of 2.31 mM had the highest signal-to-noise ratio (SNR) for a T1-weighted picture of 52.92, while IONPs with a concentration of 0.05 mM had the highest SNR for a T2-weighted image of 179.117.