Durantie Estelle, Barosova Hana, Drasler Barbara, Rodriguez-Lorenzo Laura, Urban Dominic A, Vanhecke Dimitri, Septiadi Dedy, Hirschi-Ackermann Liliane, Petri-Fink Alke, Rothen-Rutishauser Barbara
Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland.
Biointerphases. 2018 Sep 11;13(6):06D404. doi: 10.1116/1.5043373.
Inhalation of combustion-derived ultrafine particles (≤0.1 m) has been found to be associated with pulmonary and cardiovascular diseases. However, correlation of the physicochemical properties of carbon-based particles such as surface charge and agglomeration state with adverse health effects has not yet been established, mainly due to limitations related to the detection of carbon particles in biological environments. The authors have therefore applied model particles as mimics of simplified particles derived from incomplete combustion, namely, carbon nanodots (CNDs) with different surface modifications and fluorescent properties. Their possible adverse cellular effects and their biodistribution pattern were assessed in a three-dimensional (3D) lung epithelial tissue model. Three different CNDs, namely, nitrogen, sulfur codoped CNDs ( ) and nitrogen doped CNDs ( and ), were prepared by microwave-assisted hydrothermal carbonization using different precursors or different microwave systems. These CNDs were found to possess different chemical and photophysical properties. The surfaces of nanodots and were positively charged or neutral, respectively, arguably due to the presence of amine and amide groups, while the surfaces of were negatively charged, as they bear carboxylic groups in addition to amine and amide groups. Photophysical measurements showed that these three types of CNDs displayed strong photon absorption in the UV range. Both and showed weak fluorescence emission, whereas showed intense emission. A 3D human lung model composed of alveolar epithelial cells (A549 cell line) and two primary immune cells, i.e., macrophages and dendritic cells, was exposed to CNDs via a pseudo-air-liquid interface at a concentration of 100 g/ml. Exposure to these particles for 24 h induced no harmful effect on the cells as assessed by cytotoxicity, cell layer integrity, cell morphology, oxidative stress, and proinflammatory cytokines release. The distribution of the CNDs in the lung model was estimated by measuring the fluorescence intensity in three different fractions, e.g., apical, intracellular, and basal, after 1, 4, and 24 h of incubation, whereby reliable results were only obtained for . It was shown that translocate rapidly, i.e., >40% in the basal fraction within 1 h and almost 100% after 4 h, while ca. 80% of the and were still located on the apical surface of the lung cells after 1 h. This could be attributed to the agglomeration behavior of or . The surface properties of the bearing amino and amide groups likely induce greater uptake as could be detected intracellularly. This was less evident for , which bear carboxylic acid groups on their surface. In conclusion, CNDs have been designed as model systems for carbon-based particles; however, their small size and agglomeration behavior made their quantification by fluorescence measurement challenging. Nevertheless, it was demonstrated that the surface properties and agglomeration affected the biodistribution of the particles at the lung epithelial barrier .
吸入燃烧产生的超细颗粒（≤0.1微米）已被发现与肺部和心血管疾病有关。然而，碳基颗粒的物理化学性质（如表面电荷和团聚状态）与不良健康影响之间的相关性尚未确立，这主要是由于在生物环境中检测碳颗粒存在局限性。因此，作者应用模型颗粒来模拟不完全燃烧产生的简化颗粒，即具有不同表面修饰和荧光特性的碳纳米点（CNDs）。在三维（3D）肺上皮组织模型中评估了它们可能的细胞不良影响及其生物分布模式。通过使用不同的前驱体或不同的微波系统，通过微波辅助水热碳化制备了三种不同的CNDs，即氮、硫共掺杂的CNDs（ ）和氮掺杂的CNDs（ 和 ）。发现这些CNDs具有不同的化学和光物理性质。纳米点 和 的表面分别带正电或中性，这可能是由于存在胺基和酰胺基，而 的表面带负电，因为除了胺基和酰胺基外还带有羧基。光物理测量表明，这三种类型的CNDs在紫外范围内显示出强烈的光子吸收。 和 都显示出微弱的荧光发射，而 显示出强烈的发射。由肺泡上皮细胞（A549细胞系）和两种主要免疫细胞，即巨噬细胞和树突状细胞组成的3D人肺模型通过假气液界面以100微克/毫升的浓度暴露于CNDs。通过细胞毒性、细胞层完整性、细胞形态、氧化应激和促炎细胞因子释放评估，暴露于这些颗粒24小时对细胞没有产生有害影响。在孵育1、4和24小时后，通过测量三个不同部分（即顶端、细胞内和基底）的荧光强度来估计CNDs在肺模型中的分布，其中仅对 获得了可靠的结果。结果表明， 迅速转运，即1小时内基底部分中>40%，4小时后几乎100%，而 和 在1小时后约80%仍位于肺细胞的顶端表面。这可能归因于 或 的团聚行为。带有氨基和酰胺基的 的表面性质可能诱导更大的摄取，因为可以在细胞内检测到 。对于表面带有羧酸基团的 ，情况则不太明显。总之，CNDs已被设计为碳基颗粒的模型系统；然而，它们的小尺寸和团聚行为使得通过荧光测量对其进行定量具有挑战性。尽管如此，已证明表面性质和团聚影响了颗粒在肺上皮屏障处的生物分布。
