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.