Nanoparticles (NPs) exhibit unique reactivity features that stem from the spatial confinement of their reactive sites to the particle body, which typically carries electric charges. Accordingly, association of ions and molecules with NPs takes place in a local environment that may be very different from that prevailing in the bulk aqueous medium. We present a critical overview of a conceptual framework that describes the dynamic features of metal ion, M, association with different types of NPs, i.e. impermeable (hard, 2D), core–shell, and permeable (soft, 3D). The interpretation identifies the crucial role played by the particulate electric field, and elucidates the factors that determine which step in the overall association/dissociation process is the rate-limiting one. The scope encompasses delineation of the distribution of NP-associated metals, M-NP, over various intraparticulate forms, as well as description of the influence of the intraparticulate spatial distribution of reactants on the complex formation/dissociation kinetics. The connection between the chemodynamic features of M-NP entities at the intraparticulate level and their reactivity at the macroscopic scale is elaborated. These relationships are used to derive analytical expressions for the lability of M-NP entities at reactive interfaces, such as sensors and organisms. Such knowledge is required to make mechanistic links with bioavailability and ensuing toxicity. The interpretation includes formulation of the operational reaction layer at the macroscopic interface and the significance of partial size exclusion of the NP body therefrom. The concepts are illustrated by confrontation with sets of experimental data for different types of natural and engineered NPs.

中文翻译：

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金属离子与纳米粒子在水介质中的化学动力学和生物利用度

纳米颗粒（NPs）表现出独特的反应性特征，这是由于其反应位点在空间上局限在通常带有电荷的颗粒体上。因此，离子和分子与NP的缔合发生在局部环境中，该环境可能与本体水性介质中普遍存在的环境大不相同。我们提供了一个概念框架的重要概述，该框架描述了金属离子M与不同类型的NP结合的动态特征，即不可渗透的（硬的，2D的），核-壳和可渗透的（软的，3D的）。该解释确定了颗粒电场所起的关键作用，并阐明了决定整个缔合/离解过程中哪一步是限速步骤的因素。该范围包括描述NP相关金属M-NP在各种颗粒内形式上的分布，以及反应物的颗粒内空间分布对复合物形成/解离动力学的影响的描述。详细阐述了颗粒内M-NP实体的化学动力学特征与它们在宏观尺度上的反应性之间的联系。这些关系用于推导M-NP实体在反应性界面（如传感器和生物）上的不稳定性的分析表达式。需要这样的知识才能将机制与生物利用度和随之产生的毒性联系起来。该解释包括在宏观界面处的操作反应层的配方以及从中排除NP体的部分尺寸的重要性。通过与针对不同类型的天然和工程化NP的一组实验数据的对抗来说明这些概念。