Dysprosium-Modified Gold Nanoparticles As T-2ex Contrast Agents For Magnetic Resonance Imaging

With the development of high magnetic field strength in magnetic resonance imaging (MRI), there is a demand to develop MRI contrast agents to attain high relaxation effects. Compared to typical T-1 agents, the transverse relaxation rate of T-2-based contrast agents increases with increasing magnetic field strength. However, better contrast agents are needed to improve the signal-to-noise issue. Here, a series of T-2ex contrast agents composed of an Au nanoparticle (NP) and a dysprosium complex (AuNP-DyDOTA(amide)(x)) were designed. The transverse relaxivity of three molecules bearing different side arm chains were investigated. After screening by NMR signals, the transverse relaxivity of AuNP-DyDOTA(amide)(2) achieved 22.9 mM(-1) s(-1) at 9.4 T, which is higher than dysprosium-based small molecules. The in vivo results demonstrate that the AuNP-DyDOTA(amide)(2) is very efficient for specific accumulation in tumor regions and rapid metabolization was realized, making them promising for ultrahigh field strength imaging and clinical diagnosis in the future.