Iron oxide nanoparticles (IONPs) have emerged as a promising alternative to conventional contrast agents (CAs) for magnetic resonance imaging (MRI). They have been extensively investigated as CAs due to their high biocompatibility and excellent magnetic properties. Furthermore, the ease of functionalization of their surfaces with different types of ligands (antibodies, peptides, sugars, etc.) opens up the possibility of carrying out molecular MRI. Thus, IONPs functionalized with epithelial growth factor receptor antibodies, short peptides, like RGD, or aptamers, among others, have been proposed for the diagnosis of various types of cancer, including breast, stomach, colon, kidney, liver or brain cancer. In addition to cancer diagnosis, different types of IONPs have been developed for other applications, such as the detection of brain inflammation or the early diagnosis of thrombosis. This review addresses key aspects in the development of IONPs for MRI applications, namely, synthesis of the inorganic core, functionalization processes to make IONPs biocompatible and also to target them to specific tissues or cells, and finally in vivo studies in animal models, with special emphasis on tumor models.

中文翻译：

---

磁性纳米颗粒作为 MRI 造影剂。

氧化铁纳米粒子 (IONP) 已成为磁共振成像 (MRI) 中常规造影剂 (CA) 的有前途的替代品。由于它们的高生物相容性和优异的磁性，它们已作为 CA 进行了广泛的研究。此外，用不同类型的配体（抗体、肽、糖等）对其表面进行功能化的便利性开辟了进行分子 MRI 的可能性。因此，已提出用上皮生长因子受体抗体、短肽（如 RGD）或适体等功能化的 IONP 用于诊断各种类型的癌症，包括乳腺癌、胃癌、结肠癌、肾癌、肝癌或脑癌。除了癌症诊断外，还开发了不同类型的 IONP 用于其他应用，如脑部炎症的检测或血栓形成的早期诊断。本综述讨论了用于 MRI 应用的 IONPs 开发的关键方面，即无机核的合成、使 IONPs 具有生物相容性并将其靶向特定组织或细胞的功能化过程，以及最终在动物模型中的体内研究，具有特殊的强调肿瘤模型。