Department of Nanoscience and Nanotechnology, College of Natural Sciences, School of Medicine, Kyungpook National University and Hospital, Taegu 702-701, South Korea.
ACS Appl Mater Interfaces. 2010 Oct;2(10):2949-55. doi: 10.1021/am100641z.
A facile one-pot synthesis of a water-soluble MnO nanocolloid (i.e., D-glucuronic acid-coated MnO nanoparticle) is presented. The MnO nanoparticle in the MnO nanocolloid was coated with a biocompatible and hydrophilic D-glucuronic acid, and its particle diameter was nearly monodisperse and ranged from 2 to 3 nm. The average hydrodynamic diameter of the MnO nanocolloid was estimated to be 5 nm. The MnO nanoparticle was nearly paramagnetic down to T=3 K. The MnO nanocolloid showed a high longitudinal water proton relaxivity of r1=7.02 s(-1) mM(-1) with the r2/r1 ratio of 6.83 due to five unpaired S-state electrons of Mn(II) ion (S=5/2) as well as a high surface to volume ratio of the MnO nanoparticle. High contrast in vivo T1 MR images were obtained for various organs, showing the capability of the MnO nanocolloid as a sensitive T1 MRI contrast agent. The suggested three key-parameters which control the r1 and r2 relaxivities of nanocolloids (i.e., the S value of a metal ion, the spin structure, and the surface to volume ratio of a nanoparticle) successfully accounted for the observed r1 and r2 relaxivities of the MnO nanocolloid.
一种简便的水溶性 MnO 纳米胶体（即 D-葡萄糖醛酸包覆的 MnO 纳米粒子）的一锅法合成方法被提出。MnO 纳米胶体中的 MnO 纳米粒子被包覆上了生物相容性和亲水性的 D-葡萄糖醛酸，其粒径近单分散且在 2 至 3nm 范围内。MnO 纳米胶体的平均水动力直径估计为 5nm。MnO 纳米粒子在 T=3K 以下几乎具有顺磁性。MnO 纳米胶体由于 Mn(II)离子的五个未配对 S 态电子（S=5/2）以及 MnO 纳米粒子的高表面积与体积比，表现出 7.02s-1mM-1 的高纵向水质子弛豫率 r1 和 r2/r1 的比值为 6.83。各种器官的体内 T1 磁共振成像都获得了高对比度，表明了 MnO 纳米胶体作为一种灵敏的 T1MRI 造影剂的能力。提出的三个控制纳米胶体 r1 和 r2 弛豫率的关键参数（即金属离子的 S 值、自旋结构和纳米粒子的表面积与体积比）成功地解释了所观察到的 MnO 纳米胶体的 r1 和 r2 弛豫率。
