Abstract
Magnetic iron oxide nanoparticles are relatively advanced nanomaterials, and are widely used in biology, physics and medicine, especially as contrast agents for magnetic resonance imaging. Characterization of the properties of magnetic nanoparticles plays an important role in the application of magnetic particles. As a contrast agent, the relaxation rate directly affects image enhancement. We characterized a series of monodispersed magnetic nanoparticles using different methods and measured their relaxation rates using a 0.47 T low-field Nuclear Magnetic Resonance instrument. Generally speaking, the properties of magnetic nanoparticles are closely related to their particle sizes; however, neither longitudinal relaxation rate nor transverse relaxation rate changes monotonously with the particle size . Therefore, size can affect the magnetism of magnetic nanoparticles, but it is not the only factor. Then, we defined the relaxation rates (i = 1 or 2) using the induced magnetization of magnetic nanoparticles, and found that the correlation relationship between relaxation rate and relaxation rate is slightly worse, with a correlation coefficient of = 0.8939, while the correlation relationship between relaxation rate and relaxation rate is very obvious, with a correlation coefficient of = 0.9983. The main reason is that relaxation rate is related to the magnetic field inhomogeneity, produced by magnetic nanoparticles; however relaxation rate is mainly a result of the direct interaction of hydrogen nucleus in water molecules and the metal ions in magnetic nanoparticles to shorten the relaxation time, so it is not directly related to magnetic field inhomogeneity.
Highlights
Magnetic iron oxide nanoparticles (MIONPs) have developed rapidly in recent years and have been widely used in biology, physics and medicine
Magnetic nanoparticles are widely used as contrast agents for magnetic resonance imaging (MRI)
SHP series magnetic nanoparticles (Ocean Nanotech) with different nominal sizes were selected for characterization experiments, and their relaxation rates were measured using a 0.47 T low-field nuclear magnetic resonance (LF-NMR) instrument
Summary
Magnetic iron oxide nanoparticles (MIONPs) have developed rapidly in recent years and have been widely used in biology, physics and medicine. They are quite small, usually nanoscale, and because of their scale, they can manifest many unique properties, such as superparamagnetism, i.e., when the applied magnetic field approaches zero, the induced magnetization and coercivity are zero [1,2,3,4]. Some scholars used them to make some progress in the field of magnetic temperature measurement [5,6,7,8,9,10,11] Due to their low toxicity, biocompatibility, and specificity after surface modification, MIONPs can be used as a target for drug delivery and disease treatment [12,13,14,15]. MIONPs are often used as contrast agents [16,17,18,19,20] in magnetic resonance imaging (MRI), which is one of the most important imaging methods in the field of medical diagnosis and scientific research [21,22,23,24]
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