Quantifying uptake of metal nanoparticles in individual algal cells using single cell ICP-MS

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Abstract

Multiple studies have assessed the bioaccumulation of engineered metal nanoparticles (ENM) to various organisms. However, reoccurring obstacles include assessing the state of the EMN taken up by the organisms including determining parameters such as particle number and size distribution and presence of dissolved metal. Using methods such as total acid digestion gives an indication of the total mass of metal associated with the organism, but no information on size distribution nor presence of ions. Additionally, pooling of multiple organisms is often required to obtain sufficient metal content to raise above the limit of detection of the analysis method. Using single cell inductively coupled mass spectrometry (SC-ICP-MS) it is possible to gain information regarding number size distribution and presence of ions on a single cell level in, for instance, algal cells. Mono-cultured algae (Raphidocelis subcapitata) was used as test organism, as it is well-known and ecologically highly relevant. R. subcapitata was exposed to 40nm PEG coated Au NPs, CeO2 NPs and BaSO4 NPs in a ratio of 1:10 (algae:NPs) for 24, 48 and 72 hours with an initial cell density of 106 cells/mL. After exposure, the algal suspension was centrifuged at 10000g for 30 min to allow formation of a pellet and to wash the algal cells to avoid transfer of unattached NPs to the SC-ICP-MS. Three washing steps with ISO:8692 algal media was used and aliquots of the supernatant after each wash was analyzed by single particle ICP-MS to ensure removal of NPs after each washing step. Measuring the naturally occurring Zn content in the algal cells allowed to estimate the number of cells analyzed by SC-ICP-MS. The total number of intact algal cells were confirmed by coulter counting. The results for Au NPs showed an increase in most frequent number of uptake or adsorption of Au NPs per individual cell over time. One Au NP per cell as most frequent number per cell at 24 hours increased to three Au NPs per cell as most frequent number per cell after 48 hours of exposure. The most frequent number of Au NPs per cell decreased to one per cell from 48 hours to 72 hours of exposure. A possible mode of action for decreasing the number of Au NPs associated with the algal cells could be increased production of exudates, which could be investigated in future work.
Original languageEnglish
Publication date2019
Number of pages1
Publication statusPublished - 2019
Event14th International Conference on the Environemntal Effects of Nanoparticles and Nanomaterials (ICEENN 2019) - Vienna, Austria
Duration: 1 Sep 20194 Sep 2019
Conference number: 14

Conference

Conference14th International Conference on the Environemntal Effects of Nanoparticles and Nanomaterials (ICEENN 2019)
Number14
CountryAustria
CityVienna
Period01/09/201904/09/2019

Cite this

Skjolding, L. M., Mackevica, A., Pang, C., Olsson, M. E., & Baun, A. (2019). Quantifying uptake of metal nanoparticles in individual algal cells using single cell ICP-MS. Poster session presented at 14th International Conference on the Environemntal Effects of Nanoparticles and Nanomaterials (ICEENN 2019), Vienna, Austria.