Figure 5. Effect of surfactant lipids on the association of nanoparticles with alveolar macrophages.

(A) Starch- (ST) or Phosphatidylcholine-modified (PL) magnetite nanoparticles (mNP; 1.532×10¹⁰/ml) were incubated with alveolar macrophages (AM; MH-S cells) for 90 min in the absence or presence of 25, 50 or 100 µg/ml (total lipids) of surfactant-like membrane vesicles composed of dipalmitoyl-glycero-phosphocholine (DPPC), palmitoyl-oleoyl-glycero-phosphoglycerol (POPG) and palmitic acid (PA). Cells with Fl-1>10¹ were considered as positive cells for nanoparticle association and uptake (plotted as percent of positive cells with respect to total cells) compared to control (cells only). Data shown as mean ± SD (n = 6). Images are representative micrographs of AM (membrane in red) with ST-mNPs (B) or PL-mNPs (C) (in green), both in the presence of 100 µg/ml DPPC/POPG/PA. Scale bar indicates a distance of 20 µm.