氧化铁纳米粒子-胶束（ION-胶束）用于敏感（分子）磁共振成像和磁共振成像。

BACKGROUND: Iron oxide nanoparticles (IONs) are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI) was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. METHODS AND RESULTS: IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles). Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS) measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem) and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles) bound to blood clots. CONCLUSIONS: The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular) MPI and warrants further investigation of the FibPep-ION-Micelle platform for in vivo, non-invasive imaging of fibrin in preclinical disease models of thrombus-related pathologies and atherosclerosis.

背景：氧化铁纳米粒子（IONs）是一种很有前途的磁共振对比增强纳米平台。最近，磁性粒子成像（MPI）作为一种新的成像方式被引入，它能够直接可视化磁性粒子，并且可以作为比磁共振更敏感和更定量的替代方法。然而，MPI 需要具有特定磁性特性的磁性粒子才能达到最佳效果。目前市场上可买到的氧化铁制剂在 MPI 中的性能并不理想，这促使人们研究优化的合成策略。大多数合成程序旨在控制氧化铁纳米粒子的尺寸，而不是控制其磁性特性。在本研究中，我们报告了一种新型 ION 平台的合成、表征及其在敏感 MPI 和 MRI 中的应用。

方法和结果：IONs 采用热分解法合成，然后通过包封在脂质胶束中进行相转移（ION-Micelles）。接着，分析了 ION-Micelles 的材料和磁性特性。值得注意的是，振动样品磁强计测量结果表明，IONs 的有效磁核尺寸为 16nm。此外，还进行了磁性粒子谱（MPS）测量。MPS 本质上是零维 MPI，因此可以探测氧化铁制剂在 MPI 中的潜力。与市售的氧化铁制剂（Endorem、Resovist 和 Sinerem）相比，ION-Micelles 引起的 MPS 测量信号高 200 倍，因此可能允许进行更敏感的 MPI。此外，通过纤维蛋白结合肽功能化 ION-Micelles（FibPep-ION-Micelles）与血栓结合的 MPS 和 MRI 测量，展示了 ION-Micelle 平台在分子 MPI 和 MRI 中的潜力。

结论：所呈现的数据强调了 ION-Micelle 纳米平台在敏感（分子）MPI 中的潜力，并证明了 FibPep-ION-Micelle 平台在血栓相关病变和动脉粥样硬化的临床前疾病模型中用于纤维蛋白的体内、非侵入性成像的进一步研究是合理的。