Modification of classic fluorophore to possess the emission transitions between aggregation-induced emission （ALE） and intrinsic emission offers reliable approach to the design of ratiometric fluorescent sensors. In...Modification of classic fluorophore to possess the emission transitions between aggregation-induced emission （ALE） and intrinsic emission offers reliable approach to the design of ratiometric fluorescent sensors. In this study, a proton acceptor benzimidazole was integrated with BODIPY to form three compounds, BBI-1/2/3, which demonstrated the AIE （-595 nm, Iagg） in neutral aqueous medium and intrinsic BODIPY emission （-510 nm,Iint） in acidic medium. All the three showed the ratiometric pH sensing behavior in a dual excitation/dual emission mode, yet BBI-3 displayed still the dual emission ratiometric pH sensing ability. The pH-dependent emission ratio/int/Iagg of the three were fully reversible, and no interference was observed from normal abundant chemical species in live cells. Their different pKa （BBI-1, pKa 4.4; BBI-2, pKa 2.7; BBI-3, pKa 3.6） suggested that the substituents on benzimidazole moiety were essential to govern their functioning pH range. The ratiometric imaging of BBI-1 in A549 cells provided an effective intracellular pH （pHi） calibration formula corresponding to emission ratio oflJ Iint/Iagg. Ratiometric pH imaging in A549 cells upon small particle exposure confirmed the particle-induced cellular acidification with this formula. Both particle size and the chemical nature of the particle contribute to the observed acidification effect. The synchronization of lysosome disruption to cellular acidification in A549 cells upon crystalline silica exposure was directly observed for the first time with BBI-1, showing the potential application of BBI-1 in the study of silicosis and other related diseases. This study de- monstrated that endowing fluorophore with AIE/intrinsic emission transition could be a promising strategy for ratiometric sensor design.展开更多
基金supported by the National Basic Research Program of China (2015CB856300)the National Natural Science Foundation of China (21571099, 21731004)the Natural Science Foundation of Jiangsu Province (BK20150054)
文摘Modification of classic fluorophore to possess the emission transitions between aggregation-induced emission （ALE） and intrinsic emission offers reliable approach to the design of ratiometric fluorescent sensors. In this study, a proton acceptor benzimidazole was integrated with BODIPY to form three compounds, BBI-1/2/3, which demonstrated the AIE （-595 nm, Iagg） in neutral aqueous medium and intrinsic BODIPY emission （-510 nm,Iint） in acidic medium. All the three showed the ratiometric pH sensing behavior in a dual excitation/dual emission mode, yet BBI-3 displayed still the dual emission ratiometric pH sensing ability. The pH-dependent emission ratio/int/Iagg of the three were fully reversible, and no interference was observed from normal abundant chemical species in live cells. Their different pKa （BBI-1, pKa 4.4; BBI-2, pKa 2.7; BBI-3, pKa 3.6） suggested that the substituents on benzimidazole moiety were essential to govern their functioning pH range. The ratiometric imaging of BBI-1 in A549 cells provided an effective intracellular pH （pHi） calibration formula corresponding to emission ratio oflJ Iint/Iagg. Ratiometric pH imaging in A549 cells upon small particle exposure confirmed the particle-induced cellular acidification with this formula. Both particle size and the chemical nature of the particle contribute to the observed acidification effect. The synchronization of lysosome disruption to cellular acidification in A549 cells upon crystalline silica exposure was directly observed for the first time with BBI-1, showing the potential application of BBI-1 in the study of silicosis and other related diseases. This study de- monstrated that endowing fluorophore with AIE/intrinsic emission transition could be a promising strategy for ratiometric sensor design.
