College of Basic Medical Sciences, Chongqing Medical University, Chongqing 400016, China.
School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China.
ACS Nano. 2024 May 14;18(19):12453-12467. doi: 10.1021/acsnano.4c01723. Epub 2024 Apr 30.
Traditional magnetic resonance imaging (MRI) contrast agents (CAs) are a type of "always on" system that accelerates proton relaxation regardless of their enrichment region. This "always on" feature leads to a decrease in signal differences between lesions and normal tissues, hampering their applications in accurate and early diagnosis. Herein, we report a strategy to fabricate glutathione (GSH)-responsive one-dimensional (1-D) manganese oxide nanoparticles (MONPs) with improved relaxivities and achieve effective / switchable MRI imaging of tumors. Compared to traditional contrast agents with high saturation magnetization to enhance relaxivities, 1-D MONPs with weak effectively increase the inhomogeneity of the local magnetic field and exhibit obvious contrast. The inhomogeneity of the local magnetic field of 1-D MONPs is highly dependent on their number of primary particles and surface roughness according to Landau-Lifshitz-Gilbert simulations and thus eventually determines their relaxivities. Furthermore, the GSH responsiveness ensures 1-D MONPs with sensitive switching from the to mode and subcutaneous tumors to clearly delineate the boundary of glioma and metastasis margins, achieving precise histopathological-level MRI. This study provides a strategy to improve relaxivity of magnetic nanoparticles and construct switchable MRI CAs, offering high tumor-to-normal tissue contrast signal for early and accurate diagnosis.
传统的磁共振成像（MRI）造影剂（CA）是一种“始终开启”的系统，无论其富积区域如何，都会加速质子弛豫。这种“始终开启”的特性导致病变和正常组织之间的信号差异减小，阻碍了它们在准确和早期诊断中的应用。在此，我们报告了一种制备谷胱甘肽（GSH）响应的一维（1-D）氧化锰纳米粒子（MONPs）的策略，以提高弛豫率，并实现肿瘤的有效/可切换 MRI 成像。与传统的高饱和磁化强度以增强弛豫率的造影剂相比，弱 1-D MONPs 有效地增加了局部磁场的非均匀性，并表现出明显的对比。根据朗道-利夫希茨-吉尔伯特模拟，1-D MONPs 的局部磁场非均匀性高度依赖于其初级粒子的数量和表面粗糙度，从而最终决定了它们的弛豫率。此外，GSH 的响应确保了 1-D MONPs 能够从 到 模式敏感切换，并且皮下肿瘤能够清晰地描绘出神经胶质瘤和转移边缘的边界，实现精确的组织病理学水平的 MRI。这项研究提供了一种提高磁性纳米粒子弛豫率和构建可切换 MRI CA 的策略，为早期和准确诊断提供了高肿瘤与正常组织的对比信号。
