Zinc Oxide Nanoparticles Induce Necrosis and Apoptosis in Macrophages in a p47phox- and Nrf2-Independent Manner
Figure 4
Investigation of the role of ZnO solubilization on the effects in RAW 264.7 cells.
(A) FACS analysis of RAW 264.7 following a 24 h treatment with freshly prepared ZnO nanoparticles (ZnO I, 0 h), with ZnO suspension that were pre-incubated for 24 h at 37°C (ZnO I, 24 h), resuspended pellets of the 24 h pre-incubated suspension (P-ZnO I, 24 h) and the particle free supernatants collected after centrifugation of the pre-incubated suspension at 16.000 g (S-ZnO I, 24 h). All respective suspensions were prepared at 0.7 g/L, equaling the final treatment dose of 80 µg/cm2. Staurosporine (STS, 24 h, 0.1 µM) was used as positive control. Data are expressed as percentage of total cell events (n = 2). Detection of Zn using a fluorescent indicator in RAW 264.7 cells treated with control medium (B), treated for 0 h with ZnO particles 80 µg/cm2, freshly suspended (C), treated for 4 h with 5 µg/cm2 (D) or 80 µg/cm2 (E) freshly suspended ZnO particles or treated for 4 h with supernatant (F) as well as pellet (G) of a 80 µg/cm2 ZnO suspension after preincubation for 24 h at 37°C. Original magnification 100×.