Human nasal olfactory deposition of inhaled nanoparticles at low to moderate breathing rate
Human nasal olfactory deposition of inhaled nanoparticles at low to moderate breathing rate
复制标题
低至中等呼吸频率下吸入纳米颗粒的人鼻嗅觉沉积
DOI：
10.1016/j.jaerosci.2017.08.006
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发表时间：
2017-11-01
影响因子：
4.5
通讯作者：
Tu, Jiyuan
中科院分区：
文献类型：
--
作者：
Tian, Lin;Shang, Yidan;Tu, Jiyuan
嗅觉通路对吸入的纳米颗粒直接易位进入大脑很敏感，在过去几十年的许多动物研究中得到了证实。在有毒物质的情况下，极低的剂量强烈表明一种亚临床状态，防止明显的神经变性，直到多年后长期接触。有毒物质（如重金属）含量升高与人类中枢神经系统神经功能恶化之间的确切机制尚不清楚；然而，鼻嗅觉作为这种运输途径的入口，无疑是一个关键的节点，可以推断出时间过程和剂量依赖性的线索。本研究使用生理上真实的鼻腔和上气道复制品，在低至中等呼吸条件下（5-14 L/min）进行人体吸入纳米颗粒（1-100 nm）的模拟。重点是嗅觉沉积和促进这一过程的各种因素。通过二维非包裹面成像技术，对鼻腔和嗅觉的气流模式和颗粒通量进行了详细观察，发现气流模式，特别是鼻壁剪切与颗粒在超细尺度（< 1-2 nm）的运动和沉积有显著的相关性。嗅觉沉积效率极低（< 3.5%），且与整个鼻腔相比，高扩散区的嗅觉沉积效率差异明显。嗅觉沉积颗粒的入口轮廓具有高度选择性，并且一致起源于靠近鼻中隔的鼻腔上部。本研究对了解人体通过嗅觉途径对吸入纳米颗粒的吸收具有重要意义。
Olfactory pathway, susceptible for direct translocation of inhaled nanoparticles into the brain, has been verified in a number of animal studies over past decades. In case of toxic substances, the extremely low dose strongly suggests a subclinical condition that prevents noticeable neurodegeneration until years after prolonged exposure. The exact mechanism, between elevated presence of toxic substances (e.g. heavy metals) and deteriorated neurofunction in human central nervous system, is still not clear; however, nasal olfactory, being portal of the entry for such a transport route, is undoubtedly a critical junction where hint to the time course and dose dependency might be inferred. Using a physiologically realistic nasal and upper airway replica, this study performed human inhalation simulations of nanoparticles (1-100 nm) under low to moderate breathing conditions (5-14 L/min). Emphasis is on olfactory deposition and the various factors contributing to the process. Details on airflow pattern and particle flux in nasal and olfactory were made visible through a 2D unwrapped surface mapping technique, and it was found out that airflow pattern, especially nasal wall shear had a remarkable correlation to particle movement and deposition at the ultrafine scale (< 1-2 nm). Olfactory deposition efficiency was found to be extremely low (< 3.5%), and showed distinctive variation in high diffusivity region when compared to that in the entire nasal cavity. The entrance profile of olfactory deposited particles was seen to be highly selective and unanimously originated from upper section of the nostril near nasal septum. Current study is of significant value to the understanding of human uptake of inhaled nanoparticles through olfactory pathway.