Center for Molecular Imaging and Nuclear Medicine, State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
J Phys Chem Lett. 2024 Aug 29;15(34):8861-8866. doi: 10.1021/acs.jpclett.4c01876. Epub 2024 Aug 21.
Iron oxide nanoparticles (IONPs) have garnered significant interest as magnetic resonance imaging (MRI) contrast agents due to their exceptional magnetic properties and biocompatibility. Toward more precise diagnosis of diseases, the relaxometric properties of IONPs have become a key research focus. Despite extensive studies on structural factors such as size, morphology, surface modification, crystalline phase, and aggregation state, the correlation between the intrinsic structure and relaxometric behavior remains unclear, particularly for ultrasmall IONPs. To address this issue, we carefully compared IONPs with identical size, shape, and surface modification and found out strong correlations among the content of Fe ions, oxygen vacancies, and the relaxometric properties. By optimizing the reaction system, ultrasmall IONPs showing outstanding relaxometric performance, with longitudinal relaxivity up to 9.0 mM s and transverse relaxivity up to 28.5 mM s, were successfully obtained. These results underscore the pivotal role of Fe in the relaxometric properties of IONP-based MRI contrast agents.
氧化铁纳米粒子（IONPs）因其优异的磁性能和生物相容性而成为磁共振成像（MRI）造影剂的研究热点。为了更精确地诊断疾病，IONPs 的弛豫性能已成为一个关键的研究焦点。尽管已经对结构因素（如尺寸、形态、表面修饰、晶体相和聚集状态）进行了广泛的研究，但内在结构与弛豫行为之间的相关性仍不清楚，特别是对于超小 IONPs。为了解决这个问题，我们仔细比较了具有相同尺寸、形状和表面修饰的 IONPs，并发现铁离子含量、氧空位与弛豫性能之间存在很强的相关性。通过优化反应体系，成功制备了具有出色弛豫性能的超小 IONPs，其纵向弛豫率高达 9.0 mM s，横向弛豫率高达 28.5 mM s。这些结果强调了 Fe 在基于 IONP 的 MRI 造影剂弛豫性能中的关键作用。
