Water-Soluble Ultra-Small Manganese Oxide Surface Doped Gadolinium Oxide (Gd2O3@MnO) Nanoparticles for MRI Contrast Agent

We have developed ultra‐small gadolinium oxide (Gd2O3) nanoparticles, which are surface‐doped with manganese oxide (MnO) (abbreviated as Gd2O3@MnO). The surface‐doped nanoparticles ranged from 1 to 2 nm in diameter. They were further coated with hydrophilic biocompatible lactobionic acid. In‐vitro tests of the sample solution indicated clear dose‐dependent contrast enhancements in both T1 and T2 map images, showing that the nanoparticles may be used as both T1 and T2 MRI contrast agents. Their performance as a T1 MRI contrast agent was proved in vivo through T1 MR images of a mouse. Aqueous solutions of lactobionic acid coated ultra‐small Gd2O3@MnO nanoparticles (d = 1–2 nm) may be used as both T1 and T2 MRI contrast agents because of their high relaxivities. Its capability as a T1 MRI contrast agent was proved in vivo.