Method development for multiplexing bio imaging of single cells by use of LA-ICP-MS

• Applicant: Dr. Larissa Müller
• Subject Area: Analytical Chemistry
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244424891

Many biological systems contain cell population with heterogenic characteristics. To visualize the differences and to comprise their role in the system, it is necessary to analyze each cell isolated. Especially fluorescence microscopy has been established in this research field, for example for cytodiagnostics or live cell imaging. At the same time each improvement poses a new set of biochemical, cell biological and medical questions which demand the development of robust multiplexing and quantitative analytical methods to investigate in protein function, protein interaction and the molecular composition of cells. Especially the simultaneous detection of multiple proteins (multiplexing) via immunoassay in combination with fluorescence microscopy is limited by spectral overlap and saturation effects. The aim of this project is the development of analytical methods for a better imaging of metals detected by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for analysis of natural hetero elements and artificial element tags in single cells. In particular a method will be established for quantitative and multiplexing bio-imaging of single eukaryotic cells based on element labeled antibodies. The idea to develop multiplexing immunoassays for ICP-MS detection is based on the simple evaluation of the mass fingerprints, because ICP-MS is a multi-element detector and could analyze many elements of the periodic table simultaneously. Furthermore ICP-MS excels by high accuracy and high linear dynamic range.The pre-condition of immunoassays analyzed by ICP-MS is the modification of antibodies with artificial element labels. Similar to fluorescence colors, these labeled antibodies act as an indicator for the target proteins in the cell. The label is covalently bound to the antibody which recognizes the target protein (antigen) specifically via the key-lock-principle. In this way the detection of the element by ICP-MS allows the identification of the target protein. For the project three major goals can be defined: the optimization of the LA-ICP-MS hardware, the development of new labeling reagents and the introduction of single cell multiplex immunoassays based on LA-ICP-MS analysis. In addition selected fundamental applications (detection of metallo proteins in single cells, multiplex immunoassay for space resolved imaging of cell compartments, interaction of cells with nanoparticles) will be used for testing the performance of the analytical method.

• DFG Programme: Research Grants
• Participating Persons: Professor Dr. Michael Linscheid; Dr. Ute Resch-Genger