To keep pace with its rapid development an efficient approach for the risk assessment of nanomaterials is needed. Grouping concepts as developed for chemicals are now being explored for its applicability to nanomaterials. One of the recently proposed grouping systems is DF4nanoGrouping scheme. In this study, we have developed three structure-activity relationship classification tree models to be used for supporting this system by identifying structural features of nanomaterials mainly responsible for the surface activity. We used data from 19 nanomaterials that were synthesized and characterized extensively in previous studies. Subsets of these materials have been used in other studies (short-term inhalation, protein carbonylation, and intrinsic oxidative potential), resulting in a unique data set for modeling. Out of a large set of 285 possible descriptors, we have demonstrated that only three descriptors (size, specific surface area, and the quantum-mechanical calculated property ‘lowest unoccupied molecular orbital’) need to be used to predict the endpoints investigated. The maximum number of descriptors that were finally selected by the classification trees (CT) was very low– one for intrinsic oxidative potential, two for protein carbonylation, and three for NOAEC. This suggests that the models were well-constructed and not over-fitted. The outcome of various statistical measures and the applicability domains of our models further indicate their robustness. Therefore, we conclude that CT can be a useful tool within the DF4nanoGrouping scheme that has been proposed before.

中文翻译：

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根据DF4nanoGrouping方案对纳米材料进行分类的决策树模型

为了跟上其快速发展的步伐，需要一种有效的方法来评估纳米材料的风险。目前正在研究针对化学药品开发的分组概念，因为其适用于纳米材料。DF4nanoGrouping是最近提出的分组系统之一方案。在这项研究中，我们通过确定主要负责表面活性的纳米材料的结构特征，开发了三种结构-活性关系分类树模型，以用于支持该系统。我们使用了来自19种纳米材料的数据，这些数据在先前的研究中得到了广泛的合成和表征。这些材料的子集已用于其他研究（短期吸入，蛋白质羰基化和固有氧化电位），从而获得了唯一的建模数据集。在一大组285种可能的描述符中，我们已经证明仅需要使用三个描述符（大小，比表面积和量子力学计算的特性“最低未占据分子轨道”）来预测所研究的终点。分类树（CT）最终选择的最大描述符数量非常少-一个用于固有氧化电位，两个用于蛋白质羰基化，三个用于NOAEC。这表明模型结构合理，没有过度拟合。各种统计量度的结果和我们模型的适用范围进一步表明了它们的稳健性。因此，我们得出结论，CT可以成为之前已经提出过的DF4nanoGrouping方案。