Manganese oxide (MnO) nanocubes were fabricated and their surface were modified by ligand encapsulation or ligand exchange, to render them water-soluble. And then, MnO formed the hollow structure by etching using acidic solution (phthalate buffer, pH 4.0). Depending on the ligand of the MnO surface, it increases the interaction between MnO and water molecules. Also, the hollow structure of MnO, as well as the ligand, can greatly enhance the accessibility of water molecules to metal ions by surface area-to-volume ratio. These factors provide high R1 relaxation, leading to strong T1 MRI signal. We have confirmed T1-weighted MR contrast effect using 4-kinds of MnO nanocubes (MnOEn, MnOEnHo, MnOEx and MnOExHo). They showed enough a MR contrast effect and biocompatibility. Especially, among them, MnOExHo exhibited high T1 relaxivity (r1) (6.02 mM−1 s−1), even about 1.5 times higher sensitivity than commercial T1 MR contrast agents. In vitro/in vivo studies have shown that MnOExHo provides highly sensitive T1-weighted MR imaging, thereby improving diagnostic visibility at the disease site.

中文翻译：

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内部结构和表面受控的空心MnO纳米立方体可实现高灵敏度MR成像的对比效果。

制备了氧化锰（MnO）纳米立方体，并通过配体封装或配体交换对它们的表面进行了修饰，以使其具有水溶性。然后，MnO通过使用酸性溶液（邻苯二甲酸盐缓冲液，pH 4.0）蚀刻而形成中空结构。取决于MnO表面的配体，它会增加MnO与水分子之间的相互作用。而且，MnO的中空结构以及配体可以通过表面积/体积比极大地提高水分子与金属离子的可及性。这些因素可提供较高的R1弛豫度，从而产生强的T1 MRI信号。我们已经使用4种MnO纳米立方体（MnOEn，MnOEnHo，MnOEx和MnOExHo）证实了T1加权MR对比效果。他们表现出足够的MR对比效果和生物相容性。尤其是其中的MnOExHo表现出高的T1弛豫度（r1）（6。02 mM-1 s-1），甚至比市售T1 MR造影剂高1.5倍。体外/体内研究表明，MnOExHo可提供高度敏感的T1加权MR成像，从而提高了疾病部位的诊断可见度。