A novel xanthene-based fluorescence turn-on probe for highly selective detection of Hg2+ in water samples and living cells

Near-infrared fluorescent probe visual detection of Hg2+ and its application in biological system and ecological system

Mercury ion (Hg2+), a heavy metal cation with greater toxicity, is widely present in the ecological environment and has become a serious threat to human health and environmental safety. Currently, developing a solution to simultaneously visualize and monitor Hg2+ in environmental samples, including water, soil, and plants, remains a great challenge. In this work, we created and synthesized a near-infrared fluorescent probe, BBN-Hg, and utilized Hg2+ to trigger the partial cleavage of the carbon sulfate ester in BBN-Hg as a sensing mechanism, and the fluorescence intensity of BBN-Hg was significantly enhanced at 650 nm, thus realizing the visualization of Hg2+ with good selectivity (detection limit, 53 nM). In live cells and zebrafish, the probe BBN-Hg enhances the red fluorescence signal in the presence of Hg2+, and successfully performs 3D imaging on zebrafish, making it a powerful tool for detecting Hg2+ in living systems. More importantly, with BBN-Hg, we are able to detect Hg2+ in actual water samples, soil and plant seedling roots. Furthermore, the probe was prepared as a test strip for on-site determination of Hg2+ with the assistance of a smartphone. Therefore, this study offers an easy-to-use and useful method for tracking Hg2+ levels in living organisms and their surroundings.

Sulfur-based fluorescent probes for biological analysis: A review

The widespread adoption of small-molecule fluorescence detection methodologies in scientific research and industrial contexts can be ascribed to their inherent merits, including elevated sensitivity, exceptional selectivity, real-time detection capabilities, and non-destructive characteristics. In recent years, there has been a growing focus on small-molecule fluorescent probes engineered with sulfur elements, aiming to detect a diverse array of biologically active species. This review presents a comprehensive survey of sulfur-based fluorescent probes published from 2017 to 2023. The diverse repertoire of recognition sites, including but not limited to N, N-dimethylthiocarbamyl, disulfides, thioether, sulfonyls and sulfoxides, thiourea, thioester, thioacetal and thioketal, sulfhydryl, phenothiazine, thioamide, and others, inherent in these sulfur-based probes markedly amplifies their capacity for detecting a broad spectrum of analytes, such as metal ions, reactive oxygen species, reactive sulfur species, reactive nitrogen species, proteins, and beyond. Owing to the individual disparities in the molecular structures of the probes, analogous recognition units may be employed to discern diverse substrates. Subsequent to this classification, the review provides a concise summary and introduction to the design and biological applications of these probe molecules. Lastly, drawing upon a synthesis of published works, the review engages in a discussion regarding the merits and drawbacks of these fluorescent probes, offering guidance for future endeavors.

A Dicyanoisoflurone-based Near-infrared Fluorescence Probe for Highly Sensitive Detection of Hg2

Due to its high toxicity, long durability, easy absorption by aquatic organisms, and significant bioaccumulation, Hg2+ has caused substantial environmental damage and posed serious threats to human health. Therefore, effective detection of Hg2+ is of utmost importance. In this study, a turn-on fluorescent probe based on dicyanoisoflurone was developed for the detection of Hg2+. The probe exhibited near-infrared fluorescence signal at 660 nm upon excitation by 440 nm UV light in a mixture of CH3CN and HEPES buffer (4:1, v/v, 10 mM, pH = 7.5), with selective binding to Hg2+ in a molar ratio of 1:1. This binding event was accompanied by a visible color change from light yellow to orange. By utilizing the enhanced fluorescence signal change, this probe enables highly sensitive analysis and detection of Hg2+ with excellent selectivity (association constant = 1.63 × 104 M- 1), large Stokes shift (220 nm), high sensitivity (detection limit as low as 5.6 nM), short reaction time (30 s), and a physiological pH range of 7.5-9.5. The probe was successfully employed for detecting of Hg2+ in real water and living cells.

Bodipy-based quinoline derivative as a highly Hg2+-selective fluorescent chemosensor and its potential applications

A highly efficient sensor has been successfully developed using quinoline-based BODIPY compounds (8-quinoline-4,4-difluoro-4-boro-3a, 4a-diazaindacene (C1) and 7-hydroxy-8-quinoline-4,4-difluoro-4-boro-3a, 4a-diazindacene (C2) to detect Hg2+ ions. The sensor C1 exhibits remarkable selectivity in detecting Hg2+ with a limit of detection 3.06 × 10-8 mol/L. The developed chemical sensors have shown stability, cost-effectiveness, ease of preparation, and remarkable selectivity towards Hg2+ ions compared to other commonly occurring metal ions. The total recovery of the sensor C1 can be achieved by using a 0.1 mol/L solution of KI. The proposed sensor C1 has been applied to determine Hg2+ in tap and distilled water, yielding excellent results. In addition, the binding mode of C1-Hg2+ and C2-Hg2+ complexes was a 1:1 ratio confirmed by mass spectra, Job's plot, and DFT study. Moreover, the sensor C1 successfully applied for the biological studies results in negligible cytotoxicity, which demonstrates it can be used to determine Hg2+ in HT22 cells.

Recent advances in fluorescent materials for mercury(ii) ion detection

Invading mercury would cause many serious health hazards such as kidney damage, genetic freak, and nerve injury to human body. Thus, developing highly efficient and convenient mercury detection methods is of great significance for environmental governance and protection of public health. Motivated by this problem, various testing technologies for detecting trace mercury in the environment, food, medicines or daily chemicals have been developed. Among them, the fluorescence sensing technology is a sensitive and efficient detection method for detecting Hg2+ ions due to its simple operation, rapid response and economic value. This review aims to discuss the recent advances in fluorescent materials for Hg2+ ion detection. We reviewed the Hg2+ sensing materials and divided them into seven categories according to the sensing mechanism: static quenching, photoinduced electron transfer, intramolecular charge transfer, aggregation-induced emission, metallophilic interaction, mercury-induced reactions and ligand-to-metal energy transfer. The challenges and prospects of fluorescent Hg2+ ion probes are briefly presented. We hope that this review can provide some new insights and guidance for the design and development of novel fluorescent Hg2+ ion probes to promote their applications.

Research Progress on Multifunctional Fluorescent Probes for Biological Imaging, Food and Environmental Detection

There has been rapid progress in the development of fast, sensitive, cheap and low-cytotoxicity micro-molecule fluorescent probes for application in various fields, including disease diagnosis, food safety and environmental safety. As an analytical tool, dual-function fluorescent probes with dual-emission responses have attracted considerable attention due to their cost-effectiveness and efficiency over single-function sensors. This review primarily describes research progress on multifunctional probes in terms of the reaction type and coordination type, as well as the general design principles of probes. The analytes include reactive oxygen species (ROS), reactive sulfur species (RSS), harmful cations and anions, etc. Multifunctional probes for food, medical and environmental applications are listed for future research. To improve the development of rapid detection methods, trends and strategies in the development of multifunctional fluorescent probes are also discussed.