Preparation method and application of hollow nitrogen-doped carbon sphere loaded monatomic gadolinium contrast agent

The invention provides a preparation method and application of a hollow nitrogen-doped carbon sphere loaded monatomic gadolinium contrast agent. The method comprises the following steps of: preparing a size-controllable nano silicon dioxide microsphere as a template, simultaneously coating the surface of the nano silicon dioxide microsphere with dopamine and gadolinium ions, and performing high-temperature calcination to obtain nitrogen-doped carbon loaded monatomic gadolinium; and etching silicon dioxide, and performing surface coating of a hydrophilic polymer to obtain the pegylated hollow nitrogen-doped carbon sphere loaded monatomic gadolinium contrast agent. Through the method, the unique Gd-N-C structure can enable the monatomic gadolinium to be stably anchored by nitrogen atoms without falling off, so that the biological safety is improved; the surface-coated polyethylene glycol further improves the water solubility and biocompatibility; the monatomic contrast agent can fully utilize each gadolinium at