Single-Cell ICP-MS in Combination with Fluorescence-Activated Cell Sorting for Investigating the Effects of Nanotransported Cisplatin(IV) Prodrugs

The combined use of fluorescence-activated cell sorting (FACS) and single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) is reported, for the first time, in this work. It is applied to evaluate the differences between the cellular uptake of ultrasmall iron oxide nanoparticles (FeNPs) loaded with cisplatin­(IV) prodrug (FeNPs-Pt­(IV)) and cisplatin regarding cell viability. For this aim, FACS is applied to separate viable, apoptotic, and necrotic A2780 ovarian cancer cells after exposing them to the nanotransported prodrug and cisplatin, respectively. The different sorted cell populations are individually analyzed using quantitative SC-ICP-MS to address the intracellular amount of Pt. The highest Pt intracellular content occurs in the apoptotic cell population (about 2.1 fg Pt/cell) with a narrow intercellular distribution when using FeNPs-Pt­(IV) nanoprodrug and containing the largest number of cells (75% of the total). In the case of the cisplatin-treated cells, the highest Pt content (about 1.6 fg Pt/cell) could be determined in the viable sorted cell population. The combined methodology, never explored before, permits a more accurate picture of the effect of the intracellular drug content together with the cell death mechanisms associated with the free drug and the nanotransported prodrug, respectively, and opens the door to many possible single-cell experiments in sorted cell populations.