Quantification of silver nanoparticles taken up by single cells using inductively coupled plasma mass spectrometry in the single cell measurement modeElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ja00395a

• Main Authors: López-Serrano Oliver, Ana, Baumgart, Sabine, Bremser, Wolfram, Flemig, Sabine, Wittke, Doreen, Grützkau, Andreas, Luch, Andreas, Haase, Andrea, Jakubowski, Norbert
• Format: Article
• Language: English
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/c7ja00395a

The impact of nanoparticles, NPs, at the single cell level has become a major field of toxicological research and different analytical methodologies are being investigated to obtain biological and toxicological information to better understand the mechanisms of cell-NP interactions. Here, inductively coupled plasma mass spectrometry in the single cell measurement mode (SC-ICP-MS) is proposed to study the uptake of silver NPs, AgNPs, with a diameter of 50 nm by human THP-1 monocytes in a proof-of-principle experiment. The main operating parameters of SC-ICP-MS have been optimized and applied for subsequent quantitative analysis of AgNPs to determine the number of particles in individual cells using AgNP suspensions for calibration. THP-1 cells were incubated with AgNP suspensions with concentrations of 0.1 and 1 μg mL −1 for 4 and 24 hours. The results reveal that the AgNP uptake by THP-1 monocytes is minimal at the lower dose of 0.1 μg mL −1 (roughly 1 AgNP per cell was determined), whereas a large cell-to-cell variance dependent on the exposure time is observed for a 10 times higher concentration (roughly 7 AgNPs per cell). The method was further applied to monitor the AgNP uptake by THP-1 cells differentiated macrophages incubated at the same AgNP concentration levels and exposure times demonstrating a much higher AgNP uptake (roughly from 9 to 45 AgNPs per cell) that was dependent on exposure concentration and remained constant over time. The results have been compared and validated by sample digestion followed by ICP-MS analysis as well as with other alternative promising techniques providing single cell analysis. A promising analytical methodology is proposed to study nanoparticle-cell interactions providing information of the number of NPs internalized by cells or externally bound to the cell surface.