Battelle Memorial Institute , Columbus, OH , USA.
Nanotoxicology. 2014 Sep;8(6):663-75. doi: 10.3109/17435390.2013.822115. Epub 2013 Jul 31.
Spontaneous agglomeration of engineered nanoparticles (ENPs) is a common problem in cell culture media which can confound interpretation of in vitro nanotoxicity studies. The authors created stable agglomerates of iron oxide nanoparticles (IONPs) in conventional culture medium, which varied in hydrodynamic size (276 nm-1.5 μm) but were composed of identical primary particles with similar surface potentials and protein coatings. Studies using C10 lung epithelial cells show that the dose rate effects of agglomeration can be substantial, varying by over an order of magnitude difference in cellular dose in some cases. Quantification by magnetic particle detection showed that small agglomerates of carboxylated IONPs induced greater cytotoxicity and redox-regulated gene expression when compared with large agglomerates on an equivalent total cellular IONP mass dose basis, whereas agglomerates of amine-modified IONPs failed to induce cytotoxicity or redox-regulated gene expression despite delivery of similar cellular doses. Dosimetry modelling and experimental measurements reveal that on a delivered surface area basis, large and small agglomerates of carboxylated IONPs have similar inherent potency for the generation of ROS, induction of stress-related genes and eventual cytotoxicity. The results suggest that reactive moieties on the agglomerate surface are more efficient in catalysing cellular ROS production than molecules buried within the agglomerate core. Because of the dynamic, size and density-dependent nature of ENP delivery to cells in vitro, the biological consequences of agglomeration are not discernible from static measures of exposure concentration (μg/ml) alone, highlighting the central importance of integrated physical characterisation and quantitative dosimetry for in vitro studies. The combined experimental and computational approach provides a quantitative framework for evaluating relationships between the biocompatibility of nanoparticles and their physical and chemical characteristics.
工程纳米粒子（ENPs）的自发团聚是细胞培养基中的一个常见问题，这可能会混淆体外纳米毒性研究的结果解释。作者在常规培养基中制备了氧化铁纳米粒子（IONPs）的稳定团聚体，其水动力粒径（276nm-1.5μm）不同，但由具有相似表面电位和蛋白涂层的相同初级粒子组成。使用 C10 肺上皮细胞进行的研究表明，团聚体的剂量率效应可能非常显著，在某些情况下，细胞剂量的差异超过一个数量级。通过磁性粒子检测进行的定量分析表明，与大团聚体相比，小羧基化 IONP 团聚体在等效总细胞 IONP 质量剂量基础上诱导更大的细胞毒性和氧化还原调节基因表达，而胺修饰 IONP 团聚体尽管输送了相似的细胞剂量，但未能诱导细胞毒性或氧化还原调节基因表达。剂量测定建模和实验测量表明，基于输送的表面积，羧基化 IONP 的大团聚体和小团聚体对于产生 ROS、诱导应激相关基因和最终细胞毒性具有相似的固有效力。结果表明，团聚体表面的反应性基团比团聚体核心内的分子更有效地催化细胞 ROS 的产生。由于体外细胞中 ENP 输送的动态、尺寸和密度依赖性，团聚体的生物后果不能仅从静态暴露浓度（μg/ml）来识别，这突出了物理特性综合表征和定量剂量测定对于体外研究的重要性。这种联合实验和计算方法为评估纳米粒子的生物相容性与其物理化学特性之间的关系提供了一个定量框架。
