多巴胺修饰超小Gd_2O_3纳米粒子的制备及MRI评价

Preparation and MRI Evaluation of Dopamine-Modified Ultra-Small Gd_2O_3 Nanoparticles

将具有邻苯二酚结构的多巴胺用于超小Gd2O3纳米粒子的表面修饰,通过控制反应时间,制得适用于磁共振成像(MRI)增强对比度的造影剂.通过透射电镜(TEM),红外光谱(FTIR),紫外-可见吸收光谱(UV-vis)及热重分析(TGA)测试表征了多巴胺修饰Gd2O3纳米粒子的形貌、结构及组成.结果表明:平均粒径为3.7nm的Gd2O3纳米粒子经多巴胺修饰后,由于多巴胺分子中苯环的疏水性导致了一定程度的聚集;反应12h和24h对应的多巴胺修饰的超小Gd2O3纳米粒子中有机物的组成分别为34.7%和42.6%.MRI造影结果显示,多巴胺表面修饰的超小Gd2O3纳米粒子有效地增强了对比亮度,且弛豫效率和信号强度在一定浓度范围内与造影剂浓度呈正相关;反应较长时间(24h)对应的多巴胺修饰的超小Gd2O3纳米粒子的弛豫效率较高,对应的造影增强效果更好.

The dopamine with a catechol structure was used to modify ultra-small Gd2 03 nanoparticles （the diame- ter was lower than 5 nm）, which produced the positive contrast enhanced agents for magnetic resonance imaging （MRI） by regulating the reaction time. The morphology, structure and composition of the as-prepared Gd2 03 nanop- articles were characterized by transmission electron microscope （TEM）, Fourier transform infrared （FT-IR） spectros- copy, UV-vis spectroscopy and thermogravimel：ric analysis （TGA）. By the TEM observation, the Gd2 03 nanoparti- cles with a mean diameter of ca. 3.7 nm tended[ to aggregate because of the hydrophobic benzene ring in dopamine. At the same time, the TGA results showed the dopamine-modified Gd2 03 nanoparticles for the reaction time of 12 and 24 hours had the weight percentage of organic components are 34. 7% and 42. 6%, respectively. Moreover, the T1- weighted MRI-related measurements were carried out for the dopamine-modified Gd2 03 nanoparticles. The results showed that the dopamine-modified Gd2O3 nanoparticles effectively enhanced the contrast brightness, and the relaxa- tion rates and signal intensity were positively correlated with the concentration of the contrast agent. A longer reaction time （24 hours） for the surface modification of dopamine toward ultra-small Gd2 03 nanoparticles contributed to higher relaxivity and better contrast enhancement effect thereof.