FIGURE 4 |.

Images of NAD(P)H in 4T1 cells taken from a 2D monolayer culture and 3D matrix culture showing differential interference contrast microscopy (a,e), two-photon fluorescence intensity (b,f), and two-photon FLIM (c,g) along with histograms of the fluorescence lifetimes from the FLIM images (d,h). These images highlight the usefulness of two-photon excitation to image live cells in vivo as there were differences in cell metabolism, as indicated by NAD(P)H fluorescence, between cells cultured in a typical lab environment (2D monolayer) and those cultured in a more realistic environment (3D culture). Adapted with permission from [20] © 2018 International Society for Advancement of Cytometry.