Quantitative Chemical Imaging of the Intracellular Spatial Distribution of Fundamental Elements and Light Metals in Single Cells Emil Malucelli, † Stefano Iotti,* ,†,◆ Alessandra Gianoncelli, § Michela Fratini, ∥ Lucia Merolle, † Andrea Notargiacomo, ⊥ Chiara Marraccini, # Azzurra Sargenti, † Concettina Cappadone, † Giovanna Farruggia, †,◆ Inna Bukreeva, ⊥ Marco Lombardo, ‡ Claudio Trombini, ‡ Jeanette A. Maier, ∇ and Stefano Lagomarsino ○,◆ † Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40127, Italy ‡ Department of Chemistry “G. Ciamician”, University of Bologna, Bologna 40126, Italy § Elettra - Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy ∥ “Enrico Fermi" Centre MARBILab , c/o Fondazione Santa Lucia, Via Ardeatina, 306, 00179 , Roma, Italy ⊥ Institute for Photonics and Nanotechnology, Consiglio Nazionale delle Richerche, 00156 Rome, Italy # Department of Life Sciences, University of Modena e Reggio Emilia, 41125 Modena, Italy ∇ Department of Biomedical and Clinical Sciences “L. Sacco”, University of Milan, 20157 Milan, Italy ○ Institute of Chemical-Physical Processes, Sapienza University of Rome, 00185 Rome, Italy ◆ National Institute of Biostructures and Biosystems, 00136 Rome, Italy * S Supporting Information ABSTRACT: We report a method that allows a complete quantitative characterization of whole single cells, assessing the total amount of carbon, nitrogen, oxygen, sodium, and magnesium and providing submicrometer maps of element molar concentration, cell density, mass, and volume. This approach allows quantifying elements down to 10 6 atoms/μm 3 . This result was obtained by applying a multimodal fusion approach that combines synchrotron radiation microscopy techniques with off-line atomic force microscopy. The method proposed permits us to find the element concentration in addition to the mass fraction and provides a deeper and more complete knowledge of cell composition. We performed measurements on LoVo human colon cancer cells sensitive (LoVo-S) and resistant (LoVo-R) to doxorubicin. The comparison of LoVo-S and LoVo-R revealed different patterns in the maps of Mg concentration with higher values within the nucleus in LoVo- R and in the perinuclear region in LoVo-S cells. This feature was not so evident for the other elements, suggesting that Mg compartmentalization could be a significant trait of the drug-resistant cells. K nowledge of the spatial distribution and concentration of elements in cells is a challenging issue to reach. A detailed picture of the intracellular distribution of the fundamental life elements (FLE) constituting the molecules of living systems carbon (C), nitrogen (N), and oxygen (O)is still lacking. Moreover, other elements, such as light metals, play a fundamental role. Indeed, many basic aspects and regulatory mechanisms of cell functions are related to the intracellular compartmentalization of ions, whose different concentration gradients generate the electrical potentials that are the driving forces of many cellular processes. “How much? and where is it?” represents one of the archetypal questions essential in science. To answer the first question, a proper way must be chosen to express and measure the amounts of a given element: this issue is not trivial. We emphasize the importance of mapping the elemental distribution in molar concentration, which necessar- ily requires to measure both mass and volume. The concentration expressed in molarity refers to the concept of mole used in chemistry instead of units of mass. Indeed, knowledge of the mass of each of the components in a chemical system is not sufficient to define the system. It is part of the history of science that the introduction of the concept of mole Received: March 10, 2014 Accepted: April 15, 2014 Published: April 15, 2014 Article pubs.acs.org/ac © 2014 American Chemical Society 5108 dx.doi.org/10.1021/ac5008909 | Anal. Chem. 2014, 86, 5108−5115