TY - JOUR A1 - Loehr, Konrad A1 - Jakubowski, Norbert A1 - Wanka, Antje Jutta A1 - Traub, Heike A1 - Panne, Ulrich T1 - Quantification of metals in single cells by LA-ICP-MS comparison of single spot analysis and imaging JF - Journal of Analytical Atomic Spectrometry N2 - LA-ICP-MS is increasingly used for single cell analysis in two different detection modes using either the imaging mode with subcellular resolution or alternatively single spot analysis of cells with a larger laser spot size. This study compares the analytical figures of merit of both detection modes (signal to noise, precision, accuracy, throughput), as well as ease of operation and data evaluation. Adherent 3T3 fibroblast cells were stained with two metal dyes (mDOTA-Ho, Ir-DNA-intercalator) and several dozen cells were measured using both modes. We found a ten times higher throughput for single spot analysis, which has as well a straightforward data analysis, shortening the total analysis time further. The signal to noise ratio for single spot analysis was found to be slightly better compared to the signal to noise of pixels in imaging. The mean metal intensity per single cell differed by only 10% between both modes and obtained distributions were found to show no statistically significant differences. Using matrix matched calibration based on standards spotted onto nitrocellulose membrane, we achieved detection limits (10 σ) of 12 fg for Ir and 30 fg for Ho and quantified 57 ± 35 fg Ir and 1,192 ± 707 fg Ho per single cell. Compared to a conventional ICP-MS measurement of a digest of ~60,000 cells, 54 % of Ir content and 358 % Ho content was found using quantitative LA-ICP-MS. The difference might be a consequence of the two metal dyes binding to different structures of the cell and therefore might behave differently in sample preparation for conventional and LA-ICP-MS. KW - Single cell analysis KW - LA-ICP-MS PY - 2018 DO - https://doi.org/10.1039/c8ja00191j SN - 0267-9477 SN - 1364-5544 VL - 33 IS - 9 SP - 1579 EP - 1587 PB - Royal Society of Chemistry AN - OPUS4-45903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - García Fernández, J. A1 - Sánchez-González, C. A1 - Bettmer, J. A1 - Llopi, J. A1 - Jakubowski, Norbert A1 - Panne, Ulrich A1 - Montes-Bayón, M. T1 - Quantitative assessment of the metabolic products of iron oxide nanoparticles to be used as iron supplements in cell cultures JF - Analytica Chimica Acta N2 - Iron nanoparticles (NPs) metabolism is directly associated to human health due to their use as anemia treatment and should be studied in detail in cells. Here we present a speciation strategy for the determination of the metabolic products of iron oxide nanoparticles coated by tartaric and adipic acids in enterocytes-like cell models (Caco-2 and HT-29). Such methodology is based on the use of SDS-modified reversed phase high performance liquid chromatography (HPLC) separation using inductively coupled plasma-mass spectrometry (ICP-MS) as Fe selective detector. Post-column isotope dilution analysis is used as quantification tool by adding Fe-57 as isotopically enriched standard. To assess the separation capability of the method, two different iron nanostructures: iron sucrose nanoparticles -Venofer®- used as model suspension and iron tartrate/adipate-modified nanoparticles, both of about 4 nm (core size) were evaluated. The two nanostructures were injected into the system showing good peak profiles and quantitative elution recoveries (>80%) in both cases. In addition, both nanoparticulate fractions could be based-line separated from ionic iron species, which needed to be complexed with 1mM citrate to elute from the column. Exposed cells up to 0.5mM of iron tartrate/adipate-modified nanoparticles were specifically treated to extract the internalized NPs and the extracts examined using the proposed strategy. The obtained results revealed the presence of three different fractions corresponding to nanoparticle aggregates, dispersed nanoparticles and soluble iron respectively in a single chromatographic run. Quantitative experiments (column recoveries ranging from 60 to 80%) revealed the presence of the majority of the Fe in the nanoparticulated form (>75%) by summing up the dispersed and aggregate particles. Such experiments point out the high uptake and low solubilization rate of the tartrate/adipate NPs making these structures highly suitable as Fe supplements in oral anemia treatments. KW - Fe nanoparticles metabolism KW - Cells KW - HPLC-ICP-MS KW - Species-unspecific on-line isotope dilution PY - 2018 DO - https://doi.org/10.1016/j.aca.2018.08.003 SN - 0003-2670 VL - 1039 SP - 24 EP - 30 PB - Elsevier CY - Amsterdam AN - OPUS4-46817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - López-Serrano Oliver, Ana A1 - Baumgart, S. A1 - Bremser, Wolfram A1 - Flemig, Sabine A1 - Wittke, D. A1 - Grützkau, A. A1 - Luch, A. A1 - Haase, A. A1 - Jakubowski, Norbert T1 - Quantification of silver nanoparticles taken up by single cells using inductively coupled plasma mass spectrometry in the single cell measurement mode JF - Journal of Analytical Atomic Spectrometry N2 - 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-ofprinciple 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 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 (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. KW - Silbernanopartikel KW - ICP-MS KW - Einzelzellanalyse PY - 2018 DO - https://doi.org/10.1039/C7JA00395A SN - 0267-9477 VL - 33 IS - 7 SP - 1256 EP - 1263 PB - Royal Society of Chemistry CY - London AN - OPUS4-45473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -