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[Display omitted] • The high sensitivity of the probe with a detection limit of 58 nM. • Successful detection of endogenous and exogenous CO in living cells. • Capable of detecting CO in zebrafish. • NIR probe with a high signal-to-noise ratio for imaging CO in biological samples. Carbon monoxide (CO) is a highly emitted atmospheric pollutant that can pose a serious health risk when its concentration is too high. However, endogenous CO plays an important role in maintaining human health. The development of tools capable of detecting CO in environmental samples and biological samples is therefore essential. Although CO fluorescent probes have been reported, their further applications are limited by factors such as low sensitivity and emission wavelength. Here, we have constructed a CO probe with simple structure, high sensitivity, good selectivity and near-infrared (NIR) emission characteristics. The probe uses the dicyanoisophorone derivative as fluorophore and connects allyl moiety as the reaction site. After the response, the intramolecular charge transfer (ICT) process turns on and releases strong near-infrared fluorescence at 675 nm. The linear range of fluorescence intensity of the probe for CO concentration is 1–10 μM and the detection limit is as low as 58 nM. The high sensitivity and NIR emission give the probe excellent imaging of cellular exogenous and endogenous CO. Moreover, the probe can also be used to image CO in zebrafish. There is reason to believe that the probe can be a powerful tool for detecting CO concentrations in environmental samples and for analyzing the biological role of CO in organisms. [ABSTRACT FROM AUTHOR]

Highlights • Fluorometric and colorimetric modes were realized. • AIE and ICT effects controlled the detection process. • Real-time imaging were achieved in live cells and zebrafish. Abstract Since hypochlorite (ClO−) possesses the ability that oxidizes electron-rich objects with accompanying variations in spectroscopic features, we present here an effective strategy for generating new molecular-level probe that will be compatible for application in ClO− detection. This optical sensor has been established on a donor-π-acceptor (D-π-A) electronic structure derived from a pyrene derivative appended by 2-thioxo-dihydro-pyrimidine-4,6-dione (abbreviated as Py-Pd). Specifically, it can serve as a dual-mode sensor which exhibits fluorometric and colorimetric responses to the presence of hypochlorite. The high sensitivity, selectivity, fast response time (30 s) as well as low detection limit (75 nM) have been realized. Extensive spectroscopic analyses support the oxidation cleavage of bridge C C linkage leads to the transformation of Py-Pd to pyrene-2-carbaldehyde (Py-CHO). Such real-time imaging of hypochlorite has been also achieved in live cells and zebrafish model. In this sense, this molecular-based system can be employed as an indicator for early evaluation of optical responses of reactive oxygen species. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel benzocoumarin-based fluorescent probe BL for monitoring HOCl was designed and synthesized. • BL exhibits simple synthesis, excellent selectivity, fast response (<60 s), high sensitivity (DL, 5.64 nM). • BL was successfully applied to detect HClO spiked in tap water, 84 disinfectants and lake water, and has achieved satisfying recovery rates. • BL could readily fabricate solid-state visual sensors to be used to convenient detect HClO. • BL was nontoxic andsuccessfully used to monitor the variations of endogenous/exogenous HOCl in live RAW 264.7 macrophages. Hypochlorous acid (HOCl) is widely used in daily production and life. It is also a kind of endogenously produced reactive oxygen species (ROS) in the human immune system, plays a crucial role in many pathophysiological processes. This work designed and synthesized a novel based on benzocoumarin fluorescent probe BL for specific detection HOCl. BL has brilliant selectivity, high sensitivity (5.64 nM), fast response (60 s), moderate water-solubility. The intramolecular charge transfer (ICT) sensing mechanism of BL has been verified by fluorescence, UV, MS, and density functional theory (DFT) calculations. BL can make into a solid-state visual sensor to detect HOCl conveniently. BL was also applied to detect HClO spiked in tap water, 84 disinfectants, lake water, and satisfying recovery rates. Finally, BL was low toxic and used to track the variations of endogenous/exogenous HClO in living cells successfully. Totally, BL provides a powerful and reliable monitoring tool to reveal the biological functions of HOCl and ensure safe use. [ABSTRACT FROM AUTHOR]