Our knowledge of uptake, toxicity and detoxification mechanisms as related to nanoparticles’ (NPs’) characteristics remains incomplete. Here we combine the analytical power of three advanced techniques to study the cellular binding and uptake and the intracellular transformation of silver nanoparticles (AgNPs): single-particle inductively coupled mass spectrometry, mass cytometry and synchrotron X-ray absorption spectrometry. Our results show that although intracellular and extracellularly bound AgNPs undergo major transformation depending on their primary size and surface coating, intracellular Ag in 24 h AgNP-exposed human lymphocytes exists in nanoparticulate form. Biotransformation of AgNPs is dominated by sulfidation, which can be viewed as one of the cellular detoxification pathways for Ag. These results also show that the toxicity of AgNPs is primarily driven by internalized Ag. In fact, when toxicity thresholds are expressed as the intracellular mass of Ag per cell, differences in toxicity between NPs of different coatings and sizes are minimized. The analytical approach developed here has broad applicability in different systems where the aim is to understand and quantify cell–NP interactions and biotransformation.

我们对与纳米粒子 (NPs') 特性相关的吸收、毒性和解毒机制的了解仍然不完整。在这里，我们结合三种先进技术的分析能力来研究银纳米粒子 (AgNPs) 的细胞结合和摄取以及细胞内转化：单粒子电感耦合质谱法、质谱流式细胞术和同步加速器 X 射线吸收光谱法。我们的研究结果表明，尽管细胞内和细胞外结合的 AgNPs 根据其主要尺寸和表面涂层发生重大转变，但 24 小时暴露于 AgNP 的人淋巴细胞中的细胞内 Ag 以纳米颗粒形式存在。AgNPs 的生物转化以硫化作用为主，可以看作是 Ag 的细胞解毒途径之一。这些结果还表明，AgNPs 的毒性主要是由内化的 Ag 驱动的。事实上，当毒性阈值表示为每个细胞的细胞内 Ag 质量时，不同涂层和尺寸的 NP 之间的毒性差异最小化。这里开发的分析方法在旨在了解和量化细胞-NP 相互作用和生物转化的不同系统中具有广泛的适用性。