TY - JOUR A1 - Cruz-Alonso, M. A1 - Fernandez, B. A1 - Álvarez, L. A1 - González-Iglesias, H. A1 - Traub, Heike A1 - Jakubowski, Norbert A1 - Pereiro, R. T1 - Bioimaging of metallothioneins in ocular tissue sections by laser ablation-ICP-MS using bioconjugated gold nanoclusters as specific tags JF - Microchimica Acta N2 - An immunohistochemical method is described to visualize the distribution of metallothioneins 1/2 (MT 1/2) and metallothionein 3 (MT 3) in human ocular tissue. It is making use of (a) antibodies conjugated to gold nanoclusters (AuNCs) acting as labels, and (b) laser ablation (LA) coupled to inductively coupled plasma – mass spectrometry (ICP-MS).Water-soluble fluorescent AuNCs (with an average size of 2.7 nm) were synthesized and then conjugated to antibody by carbodiimide coupling. The surface of the modified AuNCs was then blocked with hydroxylamine to avoid nonspecific interactions with biological tissue. Immunoassays for MT 1/2 and MT 3 in ocular tissue sections (5 μm thick) from two post mortem human donors were performed. Imaging studies were then performed by fluorescence using confocal microscopy, and LA-ICP-MS was performed in the retina to measure the signal for gold. Signal amplification by the >500 gold atoms in each nanocluster allowed the antigens (MT 1/2 and MT 3) to be imaged by LA-ICP-MS using a laser spot size as small as 4 μm. The image patterns found in retina are in good agreement with those obtained by conventional fluorescence immunohistochemistry which was used as an established reference method. KW - Metal nanoclusters KW - Fluorescence KW - Protein imaging KW - Thin tissue sections KW - Immunohistochemistry KW - Bioconjugation KW - Carbodiimide crosslinking KW - Laser ablation KW - Mass spectrometry PY - 2018 DO - https://doi.org/10.1007/s00604-017-2597-1 VL - 185 IS - 1 SP - 1 EP - 9 PB - Springer AN - OPUS4-44022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bauer, M. A1 - Remmler, D. A1 - Dallmann, A. A1 - Jakubowski, Norbert A1 - Börner, H. G. A1 - Panne, Ulrich A1 - Limberg, C. T1 - Specific Decoration of a Discrete Bismuth Oxido Cluster by Selected Peptides towards the Design of Metal Tags JF - Chemistry A European Journal N2 - Metal tags find application in a multitude of biomedical systems and the combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers an opportunity for multiplexing. To lay the foundation for an increase of the signal intensities in such processes, we herein present a general approach for efficient functionalization of a well-defined metal oxido cluster [Bi6O4(OH)(4)(SO3CF3)(6)(CH3CN)(6)].2 CH3CN (1), which can be realized by selecting 7mer peptide sequences via combinatorial means from large one-bead one-compound peptide libraries. Selective cluster-binding peptide sequences (CBS) for 1 were discriminated from non-binders by treatment with H2S gas to form the reduction product Bi2S3, clearly visible to the naked eye. Interactions were further confirmed by NMR experiments. Extension of a binding peptide with a maleimide linker (Mal) introduces the possibility to covalently attach thiol-bearing moieties such as biological probes and for their analysis the presence of the cluster instead of mononuclear entities should lead to an increase of signal intensities in LA-ICP-MS measurements. To prove this, CBS-Mal was covalently bound onto thiol-presenting glass substrates, which then captured 1 effectively, so that LA-ICP-MS measurements demonstrated drastic signal amplification compared to single lanthanide tags. KW - Peptide library KW - Mass spectrometry KW - Laser ablation KW - Cluster KW - Bioconjugation PY - 2019 DO - https://doi.org/10.1002/chem.201805234 SN - 0947-6539 VL - 25 IS - 3 SP - 759 EP - 763 PB - John Wiley & Sons, Inc. AN - OPUS4-47324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -