Figure 6

Confocal laser scanning microscopy, ratiometric and PLIM images of the HeLa cells treated with Au NCs-Cy1 (25 μg ml⁻¹) for 2 h at 37 °C (a), Au NCs-Cy1 loaded cells that was incubated with NaHS for 1 h (b), and the cells stimulated with SNAP (c) and PPG (d) and incubated with Au NCs-Cy1 for 2 h at 37 °C. (e) Intracellular luminescence intensities recorded from the green and red channels and the ratiometric signal of green to red channel (Ratio). The luminescence intensities and ratiometric signals were determined from the cells incubated with Au NCs-Cy1 (1), in the presence of NaHS (2), and stimulated with SNAP (7) and PPG (8). Control experimental conditions: (3) luminescence intensity of the cells incubated with Au NCs-Cy1 collected at 25 °C in the presence of NaHS. (4) HeLa cells with NaHS treated with Au NCs-Cy1 (10 μg ml⁻¹) for 2 h. (5) the time of incubation of cells with NaHS was elongated to 4 h; (6) the cells were illuminated under increased laser power in the presence of NaHS. These results were obtained by flow cytometry analysis; (f) average lifetime histograms of intracellular Au NCs-Cy1, followed by incubation with NaHS and stimulation with SNAP and PPG. Excitation wavelength was 405 nm; lifetimes were collected through a 520±20 nm bypass filter.