Ratiometric sensing lysosomal pH in inflammatory macrophages by a BODIPY-rhodamine dyad with restrained FRET

Inflammation, as the pathophysiological response of body to harmful stimuli, leads to changes in cellular microenvironment. To research pH changes in lysosomes of macrophages during inflammation, we designed a FRET (Fӧrster resonance energy transfer) based probe, BDP-RhB. The probe showed good lysosome targeting ability, wide response range of pH from 8.0 to 4.0 with significant ratio (I582/I518) change from 0.6 to 3.4, and good reversibility and sustainability. By applying BDP-RhB, we found a decrease of lysosomal pH of macrophages during inflammation.