Figure 3. Detection of NO with Cu ₂FL2E produced by endothelial cells in vitro.

(a) NO detection in porcine aortic endothelial cells (PAECs); Left: 45 min incubation of Cu ₂FL2E (20 µM). Right: 45 min incubation of Cu ₂FL2E (20 µM) and H₂O₂ (150 µM). Top: bright-field images of cells. Bottom: fluorescence images of cells. Scale bar is50 µm. (b) Quantification of fluorescence intensity plotted against incubation time. (c) Detection of NO with Cu ₂FL2E in HCAECs cells, with or without NO-inhibitor (L-NAME). Shown are the fluorescence images after 45min co-incubation of the probe (Cu ₂FL2E =2 µM) with H₂O₂ (150 µM), L-NAME (100 µM), and/or ACh (10 µM) according to scheme. Scale bar is 75 µm. (d) Quantification of fluorescence intensity from (c) plotted against each condition mentioned in (c) (n = 5). Error bars indicate s.d.