“…On the basis of the ex-situ measurements, the in-situ sensing of osmotic pressures in a cell culture system with the sensors was further explored. As in our previous study, [11] confocal laser scanning microscopy 6a, Figure S11a and Figure S12a), sensitized acceptor emission (Figure 6b,f, Figure S11b and Figure S12b), and direct acceptor emission signals (Figure S11c and Figure S12c, excitation wavelength 561 nm) visualize the presence of the donor, the FRET effect, and the acceptor in the sensors, respectively. The lower fluorescence intensities of the donor signal (Figure S11a and Figure S12a) and higher intensities of the sensitized acceptor emission signal (Figure S11b and Figure S12b) in the MEM α-10% ASF qualitatively confirm the stronger FRET effect associated with the higher osmotic pressure, compared with that in 0.05% NaCl (Figure 6a,b).…”