Authors: J.K. Park, S.J. Lee
Affilation: Korea Research Institute of Chemical Technology, Korea
Pages: 363 - 366
Keywords: nano particles, MRI, multifunctional
Most of the magnetic nanoparticles based on iron oxides have been widely used experimentally for numerous in vivo applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, medical diagnostics, and therapeutics. These magnetic nanoparticles have high transverse relaxivity/longitudinal relaxivity (r2/r1) values because of their superparamagnetic character, so that they used to negative contrast agent. In the case of paramagnetic contrast agents, such as Gd3+ chelates, exhibited relatively low r2/r1 value and is revealed by a brightness which reflects the shortening of the longitudinal relaxation time T1. However, there is a demand for new and more efficient T1-weighted contrast agents because of their low relaxivity and high toxicity. Here, we report the development of a Eu3+-doped Gd2S3 nanoparticles, which can be used as molecular markers and T1-weighted MRI contrast agents. The Eu3+-doped Gd2S3 nanoparticles show a strong narrow emission band at around 614 nm and paramagnetic property. The Eu3+-doped Gd2S3 nanoparticles were synthesized by thermolysis of gadolinium acetylacetonate hydrate and europium acetylacetonate hydrate in 1-dodecanethiol at 200 ℃. The particles were isolated by centrifugation and washed several times to remove excess reaction reagents. These Eu3+-doped Gd2S3 nanoparticles show about a 5 nm particle diameter with strong emission band at 614 nm. For the bio-application, we prepared the water soluble Eu3+-doped Gd2S3 nanoparticles with 3-mercaptopropionic acid (MPA) via ligand exchange method. We invsetigate the MR images of solutions of various Eu3+-doped Gd2S3 nanoparticles concentrations as well as the commercially available positive Gadovist contrast agent as a reference. The T1-weighted images of Eu3+-doped Gd2S3 nanoparticles gradually become brighter with higher concentrations analogous to Gadovist.