Cellular binding, uptake and biotransformation of silver nanoparticles in human T lymphocytes

The combination of three techniques to study the cellular binding and uptake, and intracellular transformation of silver nanoparticles shows that despite considerable transformation, these silver nanoparticles can still be found in nanoparticulate form after a substantial amount of time. 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.

Automated summary

The study demonstrates the presence of silver nanoparticles in nanoparticulate form after being taken up by human lymphocytes. Biotransformation of AgNPs is primarily dominated by sulfidation, serving as a detoxification pathway for cells. Toxicity of AgNPs is mainly driven by internalized silver, with differences in toxicity between nanoparticles of different coatings and sizes being minimized when expressed as intracellular mass of silver per cell.