Fig. 4: EGFR signaling pathway-related electron transfer imaging in living cells.

All cells were incubated with ETTE nanoprobes and DAPI for imaging (Supplementary Fig. 25). Afterglow images and corresponding pseudo-color images of ETTE nanoprobes from A549 cells incubated without or with EGF in PBS (a) and in 10% fetal bovine serum (FBS) culture medium (b). Higher intensities reflect higher EGFR signaling activity. Color scale (ΔF/F₀): 0–1.5. Scale bar, 20 μm. The laser of 635 nm and 365 nm were used as the excitation sources, afterglow signal from the ETTE probe was obtained at 1.0 s after excitation. The imaging experiments were repeated independently three times and similar results were obtained. c The bar graph shows the relative afterglow intensities of ETTE nanoprobes. Data are presented as the mean values ± s.d.; unpaired two-tailed Student’s t-test; n = 4 independent experiments. d Schematic of EGFR signaling pathway-related electron transfer-triggered emission of ETTE nanoprobes (not to scale).