Representative fluorescence images of cell viability evaluation.

<p>HAECs cells were exposed to DEPs with three different concentrations: 10 µg/ml (row 1), 50 µg/ml (row 2), 100 µg/ml (row 3), and four treatment durations: 4 hours (column 1), 8 hours (column 2), 24 hours (column 3), and 48 hours (column 4), respectively. Cells are stained with Invitrogen LIVE/DEAD Viability/Cytotoxicity Assay Kit. Green fluorescence presents live cells, whereas red fluorescence shows dead or membrane-damaged cells. All images were obtained with 10× lens. These fluorescence images together revealed that DEPs impaired cell viability in a dosage- and a time-dependent manner. And the corresponding bright-field picture of each fluorescent image is shown as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036885#pone.0036885.s005" target="_blank">Information S5</a>, from which DEPs can be clearly seen.