Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America.
PLoS One. 2012;7(6):e38185. doi: 10.1371/journal.pone.0038185. Epub 2012 Jun 7.
The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.
高性能磁共振成像对比剂的化学性质仍然是一个活跃的研究领域。在这项工作中，我们证明了用于合成氧化石墨或石墨烯纳米粒子的高锰酸钾基氧化化学过程导致痕量的 Mn(2+)离子被限制（插层）在石墨烯片之间，并且这些锰插层石墨和石墨烯结构表现出不同的结构、化学和磁性，以及与顺磁螯合物化合物相比更高的弛豫率（高达 2 个数量级）和明显不同的核磁共振弥散谱。这些结果与其他关于单壁碳纳米管（展开的石墨烯片）内的顺磁金属离子限制的已发表报告一起表明，限制（封装或插层）顺磁金属离子在石墨烯片内，而不是石墨碳颗粒的大小、形状或结构是提高弛豫率的关键决定因素，因此，确定了纳米限制顺磁离子作为开发高弛豫率 MRI 对比剂的顺磁金属离子-石墨碳复合物的新的一般策略。
