Division of Magnetic Resonance Research, Korea Basic Science Institute (KBSI), Ochang, Chungbuk 363-883, Republic of Korea.
Langmuir. 2012 Jun 26;28(25):9634-9. doi: 10.1021/la300043m. Epub 2012 Jun 4.
We describe a simple method for synthesizing superparamagnetic nanoparticles (SPIONs) as small, stable contrast agents for magnetic resonance imaging (MRI) based on sulfobetaine zwitterionic ligands. SPIONs synthesized by thermal decomposition were coated with zwitterions to impart water dispersibility and high in vivo stability through the nanoemulsion method. Zwitterion surfactant coating layers are formed easily on oleic acid-stabilized SPIONs via hydrophobic and van der Waals interactions. Our zwitterion-coated SPIONs (ZSPIONs) had ultrathin (∼5 nm) coating layers with mean sizes of 12.0 ± 2.5 nm, as measured by dynamic light scattering (DLS). Upon incubation in 1 M NaCl and 10% FBS, the ZSPIONs showed high colloidal stabilities without precipitating, as monitored by DLS. The T2 relaxivity coefficient of the ZSPIONs, obtained by measuring the relaxation rate on the basis of the iron concentration, was 261 mM(-1) s(-1). This value was much higher than that of the commercial T2 contrast agent because of the ultrathin coating layer. Furthermore, we confirmed that ZSPIONs can be used as MR contrast agents for in vivo applications such as tumor imaging and lymph node mapping.
我们描述了一种简单的方法，用于合成超顺磁性纳米粒子（SPIONs）作为小而稳定的磁共振成像（MRI）对比剂，基于磺酸甜菜碱两性离子配体。通过热分解合成的 SPIONs 通过纳米乳液法用两性离子赋予水分散性和高体内稳定性。通过疏水力和范德华力相互作用，两性离子表面活性剂涂层很容易在油酸稳定的 SPIONs 上形成。我们的两性离子包覆的 SPIONs（ZSPIONs）具有超薄膜（约 5nm），其平均粒径为 12.0±2.5nm，通过动态光散射（DLS）测量。在 1M NaCl 和 10％FBS 孵育下，通过 DLS 监测，ZSPIONs 表现出高胶体稳定性，没有沉淀。根据铁浓度测量弛豫率得到的 ZSPIONs 的 T2 弛豫率系数为 261mM(-1)s(-1)。由于超薄膜，该值远高于商用 T2 造影剂。此外，我们证实 ZSPIONs 可用作体内应用的磁共振造影剂，例如肿瘤成像和淋巴结成像。
