International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
JST-ERATO Yamauchi Materials Space-Tectonics Project, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Inorg Chem. 2021 Nov 1;60(21):16008-16015. doi: 10.1021/acs.inorgchem.1c00456. Epub 2021 Apr 16.
The inhalation of nitric oxide (NO), which acts as a selective vasodilator of pulmonary blood vessels, is an established medical treatment. However, its wide adoption has been limited by the lack of a convenient delivery technique of this unstable gas. Here we report that a solid mixture of FeSO·7HO and a layered double hydroxide (LDH) containing nitrite (NO) in the interlayer spaces (NLDH) stably generates NO at a therapeutic level (∼40 ppm over 12 h from freshly mixed solids; ∼80 ppm for 5-10 h from premixed solids) under air flow (0.25 L min) if the NLDH has been prepared by using a reconstruction method. Mg/Al-type LDH was calcined at 550 °C to remove interlayer CO and then treated with NaNO in water to reconstruct the NLDH. This one-pot, organic solvent-free process can be performed at large scales and is suitable for mass production. Humid air promotes anion exchange between NO and SO in the solid mixture, resulting in persistent interactions of NO and Fe, generating NO. In contrast to the previously reported NLDH prepared using an anion-exchange method, the reconstructed NLDH exhibits stable and persistent generation of NO because of partial deformation of the layered structures (e.g., particle aggregation, reduced crystallinity, and enhanced basicity). Degradation of the solid mixture is suppressed under dry conditions, so that a portable cartridge column that is readily available as an NO source for emergency situations can be prepared. This work demonstrates that the interlayer nanospace of LDH serves as a reaction mediator for excellent controllability of solid-state reactions. This inexpensive and disposable NO generator will facilitate NO inhalation therapy in developing countries and nonhospital locations.
吸入一氧化氮（NO）可作为肺血管的选择性血管扩张剂，这是一种已确立的医学治疗方法。然而，由于缺乏方便的这种不稳定气体输送技术，其广泛应用受到限制。在这里，我们报告说，在空气流量（0.25 L min）下，FeSO·7HO 与层状双氢氧化物（LDH）的固体混合物（其中层间空间含有亚硝酸盐（NO））（如果 NLDH 是通过重建方法制备的），可稳定地以治疗水平（新鲜混合固体 12 小时内约为 40 ppm；预先混合固体 5-10 小时内约为 80 ppm）生成 NO，其中 NLDH 是通过重建方法制备的。将 Mg/Al 型 LDH 在 550°C 下煅烧以除去层间 CO，然后用 NaNO 在水中处理以重建 NLDH。这种一锅、无有机溶剂的方法可以在大规模下进行，适合大规模生产。湿空气促进了固体混合物中 NO 和 SO 之间的阴离子交换，导致 NO 和 Fe 之间持续的相互作用，从而生成 NO。与之前报道的通过阴离子交换方法制备的 NLDH 不同，重建的 NLDH 由于层状结构的部分变形（例如颗粒聚集、结晶度降低和碱性增强）而表现出稳定和持续的 NO 生成。在干燥条件下，固体混合物的降解受到抑制，因此可以制备出一种便携式盒式柱，作为紧急情况下的 NO 源随时可用。这项工作表明，LDH 的层间纳米空间可作为固态反应优异可控性的反应介质。这种廉价且一次性的 NO 发生器将促进发展中国家和非医院场所的 NO 吸入疗法。
