A new diketopyrrolopyrrole-based fluorescent probe (DPP-AM) was designed and synthesized for ratiometric detection of esterase and for imaging of live and dead cells in different modes. DPP-AM showed red fluorescence because of the intramolecular charge transfer (ICT) process from the DPP moiety to the pyridinium cation and gave remarkable ratio changes (about 70 folds), with the fluorescence changing from red to yellow, after treating with esterase because of the broken ICT process. Besides, the detection limit of DPP-AM toward esterase in vitro was 9.51 × 10 U/mL. After pretreating with HO and ultraviolet light radiation, the health status of TPC1 cells was successfully imaged. More importantly, DPP-AM showed yellow fluorescence in live cells and a red fluorescent signal in dead cells, indicating that DPP-AM has great potential applications for assessing esterase activity as well as for discriminating live and dead cells.

A series of NIR fluorescent probes of dibenzophenazine pyridine salt with different alkyl chain were developed for the detection of LPS. BD2C with ethyl chain exhibited a significant improvement of the singlet oxygen yield and antibacterial property.

Intracellular reactive oxygen species is involved in a wide variety of physiological and pathological processes. In this work, we have developed a new mitochondria-targeting probe (DPP-S) for superoxide anion detection with ratiometric fluorescence response. DPP-S exhibited an obvious color change from violet to orange along with a distinct fluorescence change with maximum emission peak from 652 to 545 nm in response to superoxide anion. The limit of detection of DPP-S for superoxide anion was calculated to be 20.5 nM. Imaging studies taken in MCF-7 and RAW264.7 cells showed that DPP-S could be employed as a ratiometric fluorescent probe for endogenous superoxide anion detection and imaging in living cells with a large emission shift. Furthermore, the colocalization study indicated that DPP-S can localize in mitochondria specifically. Finally, the fluorescent probe was successfully applied for superoxide anion imaging in mice.

Low-cost conjugated polymers as efficient photocatalytic semiconductor for hydrogen evolution has attracted worldwide attention in recent years. However, the narrow visible-light absorption spectrum, fast electron-hole recombination and the expensive co-catalysts...