State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, People's Republic of China.
Contrast Media Mol Imaging. 2011 Mar-Apr;6(2):110-8. doi: 10.1002/cmmi.412. Epub 2010 Nov 30.
Molecular imaging has generated a demand for more sensitive contrast agents for magnetic resonance (MR) imaging. We synthesized, by a novel one-step method, Gd(3+) incorporated mesoporous SiO(2) nanoparticles, Gd(2)O(3)@SiO(2), for use as an efficient contrast agent. The prepared nanoparticles were also coated with poly(lactic-co-glycolic acid) (PLGA). The size, morphology, composition and Brunauer-Emmett-Teller specific surface area of the nanoparticles were evaluated. The Gd(2)O(3)@SiO(2) nanoparticles possess intragranular network morphology with a uniform size distribution and an average size of approximately 20-40 nm. The PLGA-coated nanoparticles were spherical or near-spherical in shape with a diameter of approximately 120 nm, a smooth surface, and neither aggregation nor adhesion tendencies. No free Gd ions were detected to dissociate from Gd(2)O(3)@SiO(2) even up to the limit (<0.03 mg/l) of the ICP equipment (IRIS Advantage). Our theoretical computation based on density functional theory (using DMol3, Materials Studio) revealed that the Gd(2)O(3) molecules are fully absorbed on the interface of mesoporous SiO(2) with a stable state of lower energy. Both Gd(2)O(3)@SiO(2) and PLGA-coated Gd(2)O(3)@SiO(2) samples have a larger T(1) relaxivitiy than commercial gadolinium diethylene triaminepentaacetate (Gd-DTPA). In vitro and in vivo MR images using the Gd(2)O(3)@SiO(2) nanoparticles were observed with a 1.5 T clinical MR scanner and compared with the images using Gd-DTPA. The Gd(2)O(3)@SiO(2) nanoparticles display a better magnetic property than commercial Gd-DTPA. In vivo MR imaging demonstrated that the nanoparticles were mainly distributed in the liver. Strong enhancement was also detected in nasopharyngeal carcinoma CNE-2 xenografted tumors. The Gd(2)O(3)@SiO(2) nanoparticles are not only potential candidates for highly efficient contrast agents for MR imaging, but also might be developed into potent targeted probes for in vivo molecular imaging of cancer.
分子成像是磁共振成像（MRI）中对更敏感对比剂的需求。我们通过一种新的一步法合成了 Gd(3+)掺杂的介孔 SiO(2)纳米粒子 Gd(2)O(3)@SiO(2)，用作高效的对比剂。还对制备的纳米粒子进行了聚（乳酸-共-乙醇酸）（PLGA）的包覆。评估了纳米粒子的尺寸、形态、组成和比表面积。Gd(2)O(3)@SiO(2)纳米粒子具有具有均匀尺寸分布的颗粒内网络形态，平均尺寸约为 20-40nm。PLGA 包覆的纳米粒子呈球形或近球形，直径约为 120nm，表面光滑，无团聚或粘连趋势。即使在 ICP 设备（IRIS Advantage）的检测限（<0.03mg/l）以下，也没有游离的 Gd 离子从 Gd(2)O(3)@SiO(2)中解离出来。我们基于密度泛函理论（使用 DMol3、Materials Studio）的理论计算表明，Gd(2)O(3)分子完全被介孔 SiO(2)的界面吸收，处于能量较低的稳定状态。Gd(2)O(3)@SiO(2)和 PLGA 包覆的 Gd(2)O(3)@SiO(2)样品的 T(1)弛豫率均大于商用的钆二乙烯三胺五乙酸（Gd-DTPA）。使用 1.5T 临床磁共振扫描仪观察了 Gd(2)O(3)@SiO(2)纳米粒子的体外和体内磁共振图像，并与 Gd-DTPA 的图像进行了比较。Gd(2)O(3)@SiO(2)纳米粒子显示出比商用 Gd-DTPA 更好的磁性能。体内磁共振成像显示，纳米粒子主要分布在肝脏中。在鼻咽癌 CNE-2 移植瘤中也检测到了强烈的增强。Gd(2)O(3)@SiO(2)纳米粒子不仅是磁共振成像高效对比剂的潜在候选物，而且可能被开发为癌症体内分子成像的有效靶向探针。
