Hall Jackson R, Maloney Sara E, Jin Haibao, Taylor James B, Schoenfisch Mark H
Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599.
RSC Adv. 2019;9(68):40176-40183. doi: 10.1039/c9ra07367a. Epub 2019 Dec 4.
A simplified diffusion cell methodology was employed to measure the diffusion coefficient of nitric oxide (NO) through phosphate buffered saline (PBS) and artificial sputum medium (ASM)-an in vitro analog for airway mucus. Diffusion through the proteinaceous ASM yielded a significantly lower diffusion coefficient compared to PBS, which is attributed to both the physical obstruction by the mucin mesh and reactive nature of NO radicals towards the biological compounds in ASM. To further confirm that ASM was restricting NO from diffusing freely, a macromolecular propylamine-modified cyclodextrin donor (CD-PA) was employed to release the NO more slowly. The NO diffusion characteristics in ASM via the NO donor were also slower relative to PBS. As NO is likely to interact with lung cells after passing through the mucus barrier, the diffusion of both NO and the CD-PA macromolecular NO donor through differentiated lung tissue was investigated with and without an ASM layer. Comparison of NO diffusion through the three diffusion barriers indicated that the lung tissue significantly impeded NO penetration over the course of the experiment compared to PBS and ASM. In fact, the diffusion of CD-PA through the lung tissue was hindered until after the release of its NO payload, potentially due to the increased net charge of the NO donor structure. Of importance, the viability of the tissue was not influenced by the NO-releasing CD-PA at bactericidal concentrations.
采用一种简化的扩散池方法来测量一氧化氮（NO）通过磷酸盐缓冲盐水（PBS）和人工痰液培养基（ASM，一种气道黏液的体外类似物）的扩散系数。与PBS相比，通过含蛋白质的ASM的扩散产生的扩散系数显著更低，这归因于黏蛋白网的物理阻碍以及NO自由基对ASM中生物化合物的反应性。为了进一步证实ASM限制了NO的自由扩散，使用了一种大分子丙胺修饰的环糊精供体（CD-PA）来更缓慢地释放NO。通过NO供体在ASM中的NO扩散特性相对于PBS也更慢。由于NO在穿过黏液屏障后可能与肺细胞相互作用，研究了在有和没有ASM层的情况下，NO和CD-PA大分子NO供体通过分化的肺组织的扩散。通过三种扩散屏障的NO扩散比较表明，与PBS和ASM相比，在实验过程中肺组织显著阻碍了NO的渗透。事实上，CD-PA通过肺组织的扩散受到阻碍，直到其释放NO后，这可能是由于NO供体结构的净电荷增加所致。重要的是，杀菌浓度的释放NO的CD-PA对组织的活力没有影响。
