Imaging of metals in biological tissue by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS): state of the art and future developments

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is well established as a sensitive trace and ultratrace analytical technique with multielement capability for bioimaging of metals and studying metallomics in biological and medical tissue. Metals and metalloproteins play a key role in the metabolism and formation of metal-containing deposits in the brain but also in the liver. In various diseases, analysis of metals and metalloproteins is essential for understanding the underlying cellular processes. LA-ICP-MS imaging (LA-ICP-MSI) combined with other complementary imaging techniques is a sophisticated tool for investigating the regional and cellular distribution of metals and related metal-containing biomolecules. On the basis of successful routine techniques for the elemental bioimaging of cryosections by LA-ICP-MSI with a spatial resolution between 200 and ~10 µm, the further development used online laser microdissection ICP-MSI to study the metal distribution in small biological sample sections (at the cellular level from 10 µm to the submicrometer range). The use of mass spectrometric imaging of metals and also nonmetals is demonstrated on a series of biological specimens. This article discusses the state of the art of bioimaging of metals in thin biological tissue sections by LA-ICP-MSI with spatial resolution at the micrometer scale, future developments and prospects for quantitative imaging techniques of metals in the nanometer range. In addition, combining quantitative elemental imaging by LA/laser microdissection-ICP-MSI with biomolecular imaging by matrix-assisted laser desorption/ionization-MSI will be challenging for future life science research.