| AVS 59th Annual International Symposium and Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuP |
| Session: | Applied Surface Science Poster Session |
| Presenter: | H.F. Arlinghaus, University of Muenster, Germany |
| Authors: | H.F. Arlinghaus, University of Muenster, Germany F. Draude, University of Muenster, Germany S. Galla, University of Muenster, Germany A. Pelster, University of Muenster, Germany M. Körsgen, University of Muenster, Germany J. Tentschert, German Federal Institute of Risk Assessment, Germany H. Jungnickel, German Federal Institute of Risk Assessment, Germany A. Haase, German Federal Institute of Risk Assessment, Germany A. Luch, German Federal Institute of Risk Assessment, Germany T. Schwerdtle, University of Muenster, Germany J. Müthing, University of Muenster, Germany |
| Correspondent: | Click to Email |
In recent years, molecular imaging with submicron lateral resolution has become of more and more interest for characterizing specialized compounds in biological samples. As an example, nanoparticles (NPs) gain great commercial interest in the medical field due to their high mobility in human tissue. Despite broad applications close to the human body, so far, there is only little knowledge of possible toxicity. In this context, the distribution of NPs within cells is of particular interest. Moreover, not only the distribution of NPs but also elemental and molecular cellular distributions such as metabolites and lipids are interesting for medical research.
In this study, we used time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser-secondary neutral mass spectrometry (Laser-SNMS) to investigate different cells both unexposed and exposed in vitro to silver NPs (AgNPs) and arsenic species. To optimize the analysis, a special silicon wafer sandwich preparation technique was employed; this entails freeze-fracturing and washing of cell cultures that were grown on silicon wafers. The data showed that during freeze-fracturing, the cell membrane is often stripped from the cell, enabling direct analysis of the interior of the cells on one sandwich wafer and the remaining lipid membrane as a mirror image on the opposite wafer. During analysis, the signal from the nutrient materials was observed to diminish the contrast of the molecular signals in the images. By optimizing the preparation and washing procedures, both the contrast and the imaging resolution could be significantly increased due to higher molecular yields and lower background. With these optimization procedures it was possible to detect lipid ions in a higher mass range, especially from those membranes that were stripped from the cells.
Under these optimized conditions, several studies were performed to detect the distributions of trace elements in cells. One study dealt with AgNPs. In this context the uptake of AgNPs of human macrophages was measured with nanometer-scale resolution. 2D and 3D Laser-SNMS images clearly showed that AgNPs are incorporated by macrophages and in part agglomerate to silver aggregates with a diameter of ~3-7 µm. In a similar approach, the distribution of arsenic in cells was measured to obtain more information on the reasons why inorganic arsenic proves carcinogenic in humans. A comparison with ToF-SIMS data showed that especially the high elemental sensitivity of Laser-SNMS makes it possible to detect theses trace elements in cells.