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Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and detecting such thiols selectively is critical for understanding functions of biothiols. In this work, a pyridazine annelated perylene–based fluorescent probe PAPC is synthesized for highly selective detection of Cys. PAPC exhibits strong blue emission in PBS, while the red emission at 605 nm can be observed in the presence of Cys. The probe PAPC shows ratiometric fluorescence (I605/I460) detection of Cys with wide linear range of 1–120 μM and low detection limit of 0.19 μM. Super large Stokes shift (170 nm) and ratiometric fluorescence endow the probe low background signal. The discrimination of Cys over Hcy and GSH can be achieved through the difference of the ratiometric fluorescence. In addition, the probe has been proven to track Cys in real samples such as urine and HeLa cells. Therefore, PAPC probe is a promising candidate for detecting Cys in practical application. [ABSTRACT FROM AUTHOR]

A new colorimetric and fluorescence probe NRSH based on Nile-red chromophore for the detection of biothiols has been developed, exhibiting high selectivity towards biothiols over other interfering species. NRSH shows a blue shift in absorption peak upon reacting with biothiols, from 587 nm to 567 nm, which induces an obvious color change from blue to pink and exhibits a 35-fold fluorescence enhancement at 645 nm in red emission range. NRSH displays rapid (<1 min) response for H2S, which is faster than other biothiols (>5 min). The detection limits of probe NRSH towards biothiols are very low (22.05 nM for H2S, 34.04 nM for Cys, 107.28 nM for GSH and 113.65 nM for Hcy). Furthermore, NRSH is low cytotoxic and can be successfully applied as a bioimaging tool for real-time monitoring biothiols in HeLa cells. In addition, fluorescence mechanism of probe NRSH is further understood by theoretical calculations. [ABSTRACT FROM AUTHOR]

A colorimetric and ratiometric fluorescent probe DTF for HSO 3 − was synthesized from natural and renewable nopinone. The fluorescent probe DTF can quantitatively detect HSO 3 − with high selectivity, sensitivity and fast response time (60 s). The detection process was accompanied with the visible color change from yellow to colorless and the fluorescent color change from green to blue. The fluorescence intensity ratio (F 430 /F 520) was linear with the concentration of HSO 3 − in the range of 0–80 μM, with a limit detection of 79.2 nM. The sensing mechanism was confirmed by 1H NMR and HRMS spectra. Above all, the novel fluorescent probe DTF was successfully applied to determine the concentration of HSO 3 − in food samples and HeLa cells. In this manuscript, we designed and synthesized a novel nopinone-based fluorescence probe for colorimetric and ratiometric detection of HSO 3 −, with high sensitivity, good selectivity and fast response time. The novel probe DTF was successfully applied for detection of the concentration of HSO 3 − in food samples and living HeLa cells. Image 1 • This is the first report that the synthesis of HSO 3 −-specific fluorescence probe based on nopinone. • The colorimetric and ratiometric fluorescent probe DTF can quantitatively detect HSO 3 − with high selectivity, sensitivity and fast response time. • Probe DTF was successfully applied for detection of the concentration of HSO 3 − in food samples and living HeLa cells. [ABSTRACT FROM AUTHOR]