Hypochlorite (ClO-) is a highly reactive chemical extensively used in households, public areas, and various industries due to its multiple functions of disinfection, bleaching, and sterilization. However, overuse of ClO- may contaminate the water, soil, air and food, leading to negative impacts on the environments, ecosystems and food safety. Meanwhile, excessive ClO- in human body can also cause severe damage to the immune system. Thus, the development of effective and precise detection tools for ClO- is of great significance to better understand its complicated roles in environments and biosystems. Herein, a new high-performance ratiometric fluorescent probe 2-amino-3-((10-propyl-10H-phenothiazin-3-yl)methylene)-amino)maleonitrile (PD) was developed for effective detection of ClO- in various bio/environmental and food samples. Probe PD exhibits highly-specific ratiometric fluorescent response to ClO- with rapid response (< 1 min), excellent sensitivity (detection limit, 47.4 nM), wide applicable pH range (4 -12), and excellent versatility in practical applications. In practical applications, PD enables the sensitive and quantitative detection of ClO- levels in various water samples, bio-fluids, dairy products, fruits and vegetables with high-precision (recoveries, 97.00 -104.40 %), as well as the successful application for visual tracking ClO- in fresh fruits and vegetables. Furthermore, test strips containing PD offer a visual and convenient tool for quick identification of ClO- in aqueous media by the naked eye. Importantly, the good biocompatibility of PD enables its practical applications in real-time bioimaging of endogenous/exogenous ClO- levels in living cells, bacteria, onion cells, Arabidopsis, as well as zebrafish. This study provided an effective method for visual monitoring and bioimaging of ClO- levels in various environments, foods and living biosystems.

The overapplication of chemical pesticides will cause heavy pollution in water, soil, and foodstuff, and cause irreversible damage to the ecological environment and human health. Therefore, it is imperative to develop a highly sensitive and reliable tool for detecting pesticide residues in the environment. In this work, a novel nopinone-based fluorescent probe THIP-OCP for the detection of parathion-methyl was constructed from BchE inhibition principles. The ester bond in THIP-OCP was hydrolyzed by BchE, leading to the release of the fluorophore THIP-OH and a significant enhancement of the fluorescence signal at 547 nm. However, parathion- methyl could inhibit BchE activity significantly and resulted in fluorescence quenching at 547 nm. Probe THIP-OCP was effectively used to detect BchE and parathion-methyl, and the detection limits were as low as 8.56 U/L and 0.79 mu g/mL, respectively. A portable smartphone-based analysis platform for quantitative and qualitative analysis of parathion-methyl in soil was developed from probe THIP-OCP. This probe can also be used to detect butyrylcholinesterase (BchE) and parathion-methyl in living cells and zebrafish, providing a new tool for monitoring BchE and parathion-methyl in living systems, which is helpful for protecting human life and health. Therefore, the probe THIP-OCP is regarded as a promising tool for monitoring environmental safety and biological health systems.

Hg2+ is one of the most toxic heavy metal ions, which can cause air, soil, and water pollution, seriously damaging human health. Therefore, developing effective analytical methods to detect Hg2+ in environmental systems is particularly important. Fluorescent probes have been widely used to detect Hg2+ due to their advantages, such as high sensitivity, good selectivity, fast response time, and real-time online detection. In this paper, a novel turn-on fluorescent probe (2-(pyren-1-yl)-1,3-oxathiolane, POX) with 1,3-oxathiolane as receptor was designed and synthesized based on Hg2+-promoted deprotection reaction of thioacetal, and H-1 NMR, C-13 NMR, and HRMS characterized its structure. The selectivity, competitiveness, concentration titration, pH titration, time dependence, the limit of detection, and recognition mechanism of POX for the detection of Hg2+ in CH3CH2OH/H2O solution were investigated. The results showed that POX could quickly recognize Hg2+ in a wide pH range and exhibited high selectivity and sensitivity. Adding Hg2+ to the solution of POX resulted in a clear fluorescence emission peak at 386 nm, indicating that POX showed a remarkable turn-on fluorescence for Hg2+, and its recognition process was almost unaffected by other metal ions. Fluorescence titration experiments indicated that POX had a good linear response (R-2=0.999 4) in the range of Hg2+ from 0 similar to 6.5 mu mol.L-1, with a detection limit of 0.168 mu mol.L-1. The RSD of POX for detecting Hg2+ in actual water samples was less than 2.92%. The simple synthesis, easy availability of raw materials, and wide pH applicability of POX suggested that it could be used as a potential tool for the qualitative and quantitative detection of Hg2+ in the environment.