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[Display omitted] • A fluorescent probe was synthesized based on benzopyran-chromone for detection of ONOO−. • The probe shows short response time for ONOO− (<30 s). • The probe shows specifically selectivity and a very low detection limit of 22.4 nM for ONOO−. • The probe can accurately identify endogenous and exogenous ONOO− in HeLa cells. Peroxynitrite is widely present in organisms and closely related to many pathophysiological functions. Therefore, it is of great physiological significance to develop capable probes for detecting ONOO−. In this work, a novel fluorescent probe B-Ch was designed based on the intramolecular charge transfer (ICT) effect. By means of molecular engineering, the replacement from diethylamine group to hydroxyl group has improved the detection sensitivity of the probe. After the addition of ONOO−, the solution color and fluorescence showed noticeable changes, which were visible to the naked eye. The probe showed excellent advantages: visualization, good selectivity, low sensitivity (22.4 nM), good stability and biocompatibility, exogenous and endogenous imaging of ONOO− in HeLa cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • DpIn and NaIn were synthesized involving of indolium units with aryldiol moiety. • DpIn, a lysosome-targeting probe, showed strong NIR emission in viscous solutions. • NaIn was an ideal lysosome-targeting & viscous-sensitivity probe in living cells. Two novel fluorescence molecular rotors DpIn and NaIn were designed and synthesized involving of indolium units linked with meta -diphenol or ortha -naphthalenediol moiety, respectively. They underwent intramolecular charge transfer to form a cyanine-like modular system at a physiological pH. In glycerol aqueous solutions, the probe DpIn exhibited NIR strong emission (3-fold) at ca. 700 nm, while the probe NaIn displayed a turn-on emission (8-fold) with a larger Stokes shift (⊿λ ≈ 97 nm). The HeLa cell imaging experiments indicated probe DpIn and NaIn both exhibited excellent selectivity for staining intracellular lysosomes instead of mitochondria. 1H NMR spectra revealed that more electrons were accumulated around benzene ring of indolium groups, which could be the evidence for its basic character leading to the lysosomes targeted staining. Furthermore, the probe NaIn proved to be an ideal lysosome-targeting tracer for monitor the changes of viscosity caused by stimuli in living cells. [ABSTRACT FROM AUTHOR]

• A red emitting fluorescence probe (TPA-CPO) was designed for HSA. • The recognition mechanism was based on TICT. • TPA-CPO bind IB domain of HSA that avoided the interference of many drugs. • TPA-CPO successfully applied serum protein imaging in HeLa cells. A red emitting fluorescence probe, TPA-CPO, based on twisted intra-molecular charge transfer (TICT) was designed and synthesized. The spectra results displayed that TPA-CPO could sense HSA with excellent properties including significant fluorescence enhancement, long emission wavelength, large stokes shift, and wide linear range. The recognition mechanism was proved that TPA-CPO could bind to domain IB of HSA and its TICT process was suppressed by utilizing hydrophobic cavity and low polarity of HSA. TPA-CPO bind to domain IB instead of common drug sites of HSA could effectively avoid interference from most drugs. The selective response of TPA-CPO allowed quantitative detection of HSA with sensitivity limit of 13.65 µg/mL. What's more, it successfully achieved HSA imaging in HeLa cells. [ABSTRACT FROM AUTHOR]

In this paper, a photoinduced electron transfer (PET)& twisted intramolecular charge transfer (TICT)-based fluorescent probe (1) for detecting biothiols (GSH/Cys/Hcy) and hydrogen sulfide with fluorescence turn on was developed. The probe could recognize hydrogen sulfide over primary ions and selectively detect GSH/Cys/Hcy over other amino acids with fluorescence turn-on (an ESIPT process). H 2 S can be distinguished from GSH/Cys/Hcy with wavelength shift by UV–Vis spectra. In addition, detection limits for H 2 S/GSH/Cys/Hcy of probe 1 were 1.42 μM (0–100 μM), 0.13 μM (0–40 μM), 0.27 (0–30 μM), 0.22 μM (0–40 μM), respectively. The proposed thiolysis of the 2,4-dinitrochlorophenyl ether reaction in identification process was verified by the characteristic peak in 1H NMR and HRMS spectra. Finally, the biological imaging experiments and low cytotoxicity investigations in HeLa cells demonstrated that probe 1 could provide a promising method for the determination of H 2 S and biothiols in aqueous solution and living cells. Unlabelled Image • A PET&TICT-based fluorescent probe 1 for H 2 S and GSH/Cys/Hcy has been developed. • Probe 1 possesses a high selectivity toward H 2 S and GSH/Cys/Hcy over amino acids. • The detection limit of probe 1 for H 2 S was 1.42 μM (in a range of 0–100 μM). • The CDL of probe 1 toward GSH/Cys/Hcy were 0.13 μM, 0.27 μM, 0.22 μM, respectivly. • The application of probe 1 for H 2 S imaging in HeLa cells was also achieved. [ABSTRACT FROM AUTHOR]