Because of the toxicity of Gd(III) complexes and the poor T₁ magnetic resonance imaging (MRI) contrast of superparamagnetic iron oxide, the development of new stable, non-toxic, and efficient contrast agents is desirable. Herein, tannic acid (TA), a large natural polyphenol, and bovine serum albumin (BSA) were used to construct non-toxic Fe(III) complexes with increased relaxivity based on a strategy slowing the molecular spin. Compared with the commercial T₁ contrast agent Magnevist, TA-Fe@BSA not only exhibits comparable T₁ MRI contrast enhancement under 0.5, 1 and 7 T magnetic fields both in vitro and in vivo, but also has better stability and biocompatibility. Moreover, TA-Fe@BSA with near-infrared (NIR) absorption demonstrates efficient tumor ablation via photothermal effects. These results demonstrate their strong potential as an alternative T₁ MRI contrast agent and tumor theranostics agent in clinical settings.

由于Gd（III）配合物的毒性和超顺磁性氧化铁的T ₁磁共振成像（MRI）对比差，因此需要开发出新的稳定，无毒和有效的对比剂。在本文中，基于减慢分子自旋的策略，使用鞣酸（TA），大型天然多酚和牛血清白蛋白（BSA）来构建具有增加的弛豫性的无毒Fe（III）复合物。与商业相比Ť ₁造影剂马根维显，TA-铁@ BSA不仅表现出可比Ť ₁个都为0.5，1和7Ť磁场MRI对比增强的体外和体内，还具有更好的稳定性和生物相容性。此外，具有近红外（NIR）吸收的TA-Fe @ BSA通过光热效应证明有效的肿瘤消融。这些结果证明了它们在临床环境中作为替代性T ₁ MRI造影剂和肿瘤治疗剂的强大潜力。