Application of online sample introduction systems for single-cell analysis with ICP-MS

Global cell population data cover only information of an average cell culture and not the information of one individual cell. The way to address some individual properties of single cells within a population has been traditionally done by flow cytometry, which often reveals cell-to-cell differences and thereby, the heterogeneity of a cell population. An extension of this concept was implemented in the so-called mass cytometry, by which specific cell biomarkers are labeled with metal-containing probes that are further determined, simultaneously and on each cell, using ICP-TOF-MS technology. Moreover, a growing field of research focused on the monitoring of the variations on the elemental composition of single cells using ICP-MS has arisen. Such variations can be associated with a differential uptake when exposed to certain external stimuli (e.g., exposure to nanostructured compounds or metallodrugs) or to naturally occurring variations associated with different aspects of the genome, transcriptome, or metabolome. The evaluation of such differences might serve to elucidate biochemical mechanistic pathways that can be further associated with pathological conditions like cancer. This chapter summarizes the main aspects to consider on single-cell analysis in order to perform elemental analysis in cell suspensions using ICP-MS as a detector followed by the most relevant applications published in the last years.