Abstract
Cancer theranostics using magnetic nanoparticles such as the hyperthermia treatment and magnetic particle imaging have been developed. Magnetic relaxation was the important mechanism determining magnetization dynamics of magnetic nanoparticles. In this study, to observe the tumor microenvironment with magnetic particle imaging, the magnetic relaxation property of magnetic nanoparticles injected into tumor implanted on a mouse body was investigated. The magnetic relaxation time spectrum as the magnetization distribution was analyzed from the magnetic relaxation process by the time-domain measurement, which affected by the properties of surroundings of magnetic nanoparticles particularly because of Brownian relaxation. Magnetic nanoparticles dispersed in the viscous medium and solidified with an epoxy resin were also prepared as the non-biological samples. By comparing the magnetic relaxation time spectrum in the tumor with that in non-biological samples, the properties of the tumor microenvironment were evaluated, which is applicable to the low-invasive approach for analyzing a tumor tissue without dissection.
