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 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 U6 - 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 - Löhr, Konrad A1 - Traub, Heike A1 - Wanka, Antje Jutta A1 - Panne, Ulrich A1 - Jakubowski, Norbert T1 - Quantification of metals in single cells by LA-ICP-MS: Comparison of single spot analysis and imaging 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 (10s) of 12 fg for Ir and 30 fg for Ho and quantified 57 +/-35 fg Ir and 1192 +/- 707 fg Ho per single cell. Compared to a conventional ICP-MS measurement of a digest of about 60000 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 - Cells KW - Laser ablation KW - ICP-MS KW - Metals KW - Quantification PY - 2018 U6 - https://doi.org/10.1039/c8ja00191j SN - 0267-9477 VL - 33 IS - 9 SP - 1579 EP - 1587 PB - RSC Royal Society of Chemistry CY - London AN - OPUS4-46441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wanka, Antje Jutta A1 - Schwab, Karima A1 - Theuring, Franz A1 - Müller, Larissa A1 - Jakubowski, Norbert A1 - Lauer, Dilyara T1 - Novel antibody tagging strategy using lanthanide loaded NHS-dota-ester for the application in highly selective LA-ICP-MS-based immunoassays N2 - Using metal tagged antibodies for multiplex immunoassays is an important aspect in the research field of bioanalytics. Various tagging strategies have been published, however the formed antibody conjugates were described only rudimentarily. We present an inexpensive, simple and fast DOTA-NHS-ester tagging strategy and the characterization of the conjugates. The monoclonal anti-beta-actin-antibody was used as model system and was modified with the bifunctional ligand DOTA-NHS-ester complexing monoisotopic lanthanide ions. In contrast to the antibody tagging with other tags based on maleimide chemistry the DOTA-NHS-ester reacts with unprotonated amino groups instead of free sulfhydryl groups. The great advantage of this is that a partially reduction of the antibody is not required and therefore the antibody remains intact. The characterization of the conjugates by different analytical techniques demonstrates that no antibody fragments are formed. A mean tagging degree of 8 tags/antibody was determined. The applicability of this tagging strategy is shown in first results of an Alzheimer’s disease study in a mouse model. We have chosen three different NHS-DOTA-ester tagged antibodies for multielement LA-ICP-MS based bioimaging of mice brain tissue. The artificial introduced lanthanides as well as naturally occurring elements were analyzed simultaneously and differences between transgenic and wild-type animals are presented. T2 - Metallomics CY - Wien, Austria DA - 13.08.2017 KW - Antibody tagging KW - LA-ICP-MS based immunoassays PY - 2017 AN - OPUS4-41877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -