非Gd型T₁造影剂的开发是近年来MRI造影剂的重要研究方向。本工作通过高温热分解法制备了粒径为（3.02±0.62）nm的掺杂Zn的氧化铁纳米颗粒（ZnFe₂O₄），其r₁弛豫度为2.5 L/（mmol·s），r₂/r₁比值为2.2。合成方法简便、经济，容易实现大量制备。以生物相容性的PO-PEG分子对颗粒进行修饰，使颗粒相转移至水溶液中，可保持长期稳定分散。最后，以ZnFe₂O₄为造影剂，对小鼠肿瘤部位进行MR成像，获得~11%的信号增强。本研究工作显示ZnFe₂O₄@PO-PEG具备作为高安全性非钆型T₁造影剂并应用于实际MR造影成像的良好潜力。

Nongadoliniumbased T₁  contrast agents have attracted great interest in recent years. In this work, (3.02±0.62) nm zincdoped iron oxide nanoparticles (ZnFe₂O₄) with a high r₁ relaxivity of 2.5 L/（mmol·s） and low r₂/r₁ ratio of 2.2 are synthesized using a onepot thermal decomposition process. The synthetic procedure is simple, cost effective, and easy to scale up. The nanoparticles are modified with a biologically compatible ligand POPEG. Due to the hydrophilic polymer coating, the particles are highly dispersible and stable in aqueous solution. Finally, we applied the nanoparticles to in vivo magnetic resonance imaging and obtained a relative signal enhancement of 11% at the tumor region. This study revealed ZnFe₂O₄^@PO-PEG as a potential candidate for a nongadoliniumbased T₁ contrast agent with extraordinary biosafety.