Magnetic Field-Optimized Paramagnetic Nanoprobe for T 2 / T 1 Switchable Histopathological-Level MRI

作者：Linlin Huo, Jie Zeng, Zhenyu Wang, Xin Sun, Yu Guo, Zhile Cao, Shiqi Zhu, Mingya Tan, Muyao Li, X. Chen, Zhenghuan Zhao · 发表于：ACS Nano · 年份：2024 · DOI：10.1021/acsnano.4c01723 · 被引用次数：19 · 研究领域：Nanoparticle-Based Drug Delivery、Advanced MRI Techniques and Applications、Nanoplatforms for cancer theranostics

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 T 2 relaxivities and achieve effective T 2 / T 1 switchable MRI imaging of tumors. Compared to traditional contrast agents with high saturation magnetization to enhance T 2 relaxivities, 1-D MONPs with weak M s effectively increase the inhomogeneity of the local magnetic field and exhibit obvious T 2 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 T 2 relaxivities. Furthermore, the GSH responsiveness ensures 1-D MONPs with sensitive switching from the T 2 to T 1 mode in vitro 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 T 2 relaxivity of magnetic nanoparticles and construct switchable MRI CAs, offering high tumor-to-normal tissue contrast signal for early and accurate diagnosis.