Abstract
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 improvedrelaxivities and achieve effective/switchable MRI imaging of tumors. Compared to traditional contrast agents with high saturation magnetization to enhancerelaxivities, 1-D MONPs with weakeffectively increase the inhomogeneity of the local magnetic field and exhibit obviouscontrast. 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 theirrelaxivities. Furthermore, the GSH responsiveness ensures 1-D MONPs with sensitive switching from thetomodeand subcutaneous tumors to clearly delineate the boundary of glioma and metastasis margins, achieving precise histopathological-level MRI. This study provides a strategy to improverelaxivity of magnetic nanoparticles and construct switchable MRI CAs, offering high tumor-to-normal tissue contrast signal for early and accurate diagnosis.
Overview
- The study aims to develop glutathione (GSH)-responsive one-dimensional (1-D) manganese oxide nanoparticles (MONPs) with improved relaxivities for effective and switchable magnetic resonance imaging (MRI) of tumors. The hypothesis being tested is that 1-D MONPs with weaker saturation magnetization but higher relaxivities will exhibit better contrast and inhomogeneity of the local magnetic field, leading to more accurate and early diagnosis of tumors. The methodology used for the experiment includes the synthesis of 1-D MONPs, characterization of their properties, and in vivo MRI imaging of tumors. The primary objective of the study is to improve the relaxivity of magnetic nanoparticles and construct switchable MRI contrast agents for precise tumor-to-normal tissue contrast signal in early and accurate diagnosis of tumors.
Comparative Analysis & Findings
- The study compares the contrast and relaxivity of traditional MRI contrast agents with 1-D MONPs. The results show that 1-D MONPs with weaker saturation magnetization but higher relaxivities exhibit better contrast and inhomogeneity of the local magnetic field, leading to more accurate and early diagnosis of tumors. The study also finds that 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. This inhomogeneity eventually determines their relaxivities, which are critical for achieving high tumor-to-normal tissue contrast signal in MRI.
Implications and Future Directions
- The study's findings have significant implications for the development of switchable MRI contrast agents for precise and accurate diagnosis of tumors. The study identifies the importance of improving relaxivity and inhomogeneity of the local magnetic field in MRI contrast agents. The study also suggests future research directions to further optimize the properties of 1-D MONPs, such as increasing their number of primary particles and surface roughness, to achieve even higher relaxivities and inhomogeneity of the local magnetic field. Additionally, the study highlights the potential of GSH-responsive MRI contrast agents for targeted delivery to tumors and for personalized medicine.