Branched Polyethylenimine-Superparamagnetic Iron Oxide Nanoparticles (bPEI-SPIONs) Improve the Immunogenicity of Tumor Antigens and Enhance Th1 Polarization of Dendritic Cells

Figure 2

Characterization of U266 cells after UVB irradiation in the presence or absence of bPEI-SPIONs. (a) Dying U266 cells were measured using flow cytometry with propidium iodide and annexin-V. (b) bPEI-SPIONs accelerated cell death with UVB irradiation after 2 h incubation. (c) Cell viability was confirmed by Trypan blue exclusion method. (d) Intracellular reactive oxygen species (ROS) production in U266 was measured based on the fluorescence intensity of 2′,7′-dichlorofluorescein-diacetate (DCFH-DA) and confirmed using N-acetylcysteine (NAC), which blocks ROS production. bPEI-SPIONs induced high levels of ROS in U266 cells after UVB irradiation. Intracellular ROS (shaded histogram) production is indicated by the mean fluorescence intensity (MFI) compared to isotype controls (open histogram). (e) 5-Fluorouracil treated cells were used as apoptotic pathway control. bPEI-SPION 2 h postirradiated cells and 16 h postirradiated cells represented similar pattern of apoptosis markers (cleaved caspase 3, cleaved caspase 8) of control. Data are representative of three independent experiments.

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