Fig. 6.

(a) Confocal fluorescence microscopy images of HeLa cells incubated with 10 μM of probe A under varying hypoxic conditions induced by CoCl₂ at concentrations of 0, 50, 100, and 150 μM. The green channel (channel I) was used to detect the visible fluorescence of probe A in the emission range of 425–525 nm, while the red channel (channel II) captured near-infrared fluorescence in the range of 600–675 nm. Green fluorescence was visualized using Alexa Fluor 405 (excitation at 405 nm), and red fluorescence was detected using Alexa Fluor 568 (excitation at 559 nm). All images are presented with a scale bar of 50 μm. (b) Histograms depicting the emission intensities of channel I (green) and channel II (red) (top), and the fluorescence intensity ratio of channel II to channel I for probe A in HeLa cells (bottom) under different CoCl₂ concentrations, as quantified from the fluorescence images with SD bars based on n = 3.