▎ 摘　　要

NOVELTY - Graphene quantum dots and gadolinium ion chelate, comprises nanomaterials with dendritic morphology formed by the coordination and self-assembly of graphene quantum dots and gadolinium ion, where the surface has hydrophilic groups comprising hydroxy, carboxy and amino groups. USE - The chelate is useful for preparing a medical image developer comprising a magnetic resonance imaging contrast agent and a fluorescent imaging developer (all claimed). ADVANTAGE - The chelate: is easy to disperse in water or a aqueous system; and has good biocompatibility and low toxicity, show an excellent T1 weighted contrast performance in a 1.5 T magnetic resonance test system, and has an r1 relaxation rate as high as 72 mM-1second-1. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing graphene quantum dots and gadolinium ion chelate, comprising preparing graphene oxide by Hummers method, and then heating and oxidizing to obtain graphene quantum dots, and finally combined with gadolinium cation chelation forms stable graphene quantum dots and gadolinium ion chelate.