Eu-complex/PVK Pdots with long luminescence lifetime. (a) Emission spectra of Eu15F/PVK Pdots and 300 nm diameter R300 fluorescent beads (excited at 342 nm). (b–d) Time-gated and ungated single particle images of Eu15F/PVK Pdots, R300 beads, and mixtures of Eu15F/PVK Pdots and R300 beads, respectively: top, gated; bottom, ungated; scale bar represents 5 µm. (e–g) Ungated fluorescence image, bright field image, and time-gated fluorescence image of Eu15F/PVK Pdots in MCF-7 cells; scale bar represents 50 µm. (h) 3D surface plot of ungated image from (e). (i) 3D surface plot of gated image from (g). Reproduced in part from Semiconducting Polymer Dots Doped with Europium Complexes Showing Ultranarrow Emission and Long Luminescence Lifetime for Time-Gated Cellular Imaging. Sun, W.; Yu, J.; Deng, R.; Rong, Y.; Fujimoto, B.; Wu, C.; Zhang, H.; Chiu, D. T. Angew. Chem. Int. Ed. Engl., Vol. 52, Issue 43 (ref 22). Copyright 2013 Wiley.