Gadolinium (III)-based T₁ contrast agents have been widely used in clinical MRI. In this study, salicylic acid-gadolinium chelate was prepared via directly coordination reaction of gadolinium ion and salicylic acid. Then, three polyethylene glycols with different molecular weight were modified on the surface of salicylic acid-gadolinium by simple chemical coupling to construct three core-shell structural Gd based composites. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization results show that the composite is a spherical particle with a diameter of about 100–200 nm. The longitudinal relaxation rate r₁ of the Gal-PEG-2000 is 11.097 (mmol/L)⁻¹/s, and the ratio of r₂/r₁ is as low as 2.53. The composite shows good liver and intestines MRI performances after being used in in vivo imaging, showing a good prospect of biological application.

基于钆(III)的T ₁造影剂已广泛用于临床MRI。本研究通过钆离子与水杨酸的直接配位反应制备水杨酸-钆螯合物。然后，通过简单的化学偶联在水杨酸-钆表面修饰三种不同分子量的聚乙二醇，构建了三种核壳结构的钆基复合材料。扫描电子显微镜（SEM）和透射电子显微镜（TEM）表征结果表明，复合材料为球形颗粒，直径约为100-200 nm。Gal-PEG-2000的纵向弛豫率r ₁为11.097 (mmol/L) ^-1 /s，r₂ / r ₁低至 2.53。该复合材料用于活体成像后，表现出良好的肝肠MRI表现，具有良好的生物应用前景。