Influence of free Selol (S) or Selol-PVM/MA nanocapsules (SPN) on A549 cells. Flow cytometry study of cells stained with propidium iodide (PI) and/or annexin V-FITC. The positive cells are shown as percentages in each quadrant: PI+ (Q1), Annexin V+ (Q3), double-negative PI− Annexin V− (Q4), and double-positive cells PI+ Annexin V+ (Q2). Negative control (a). Annexin V+ control (b). PI+ control (c). Untreated cells (d). Similar membrane integrity was observed after S (e) and SPN (f) treatments.