Zhao Li

Food safety remains a global concern, with hazardous substances potentially occurring throughout the entire food supply chain, from farm to table. Therefore, rapid and reliable detection methods are critical for food safety monitoring. Small Molecular Organic Fluorescent Probes (SMOFPs) have emerged as powerful tools for detecting food contaminants due to their high sensitivity, selectivity, rapid response, ease of operation, and low cost. This review provides a comprehensive overview of recent advances in SMOFPs for food safety applications, covering fundamental design principles and sensing mechanisms. It summarizes selected publications from 2015 to 2025 on the detection of harmful ions, food additives, foodborne pathogens, and pesticide or veterinary drug residues. In addition, the integration of SMOFPs with advanced smart devices for real-time monitoring is highlighted. This review aims to provide valuable insights and practical guidance to bridge the gap between laboratory research and real-world applications, contributing to improved food quality and public health.

Hydroxyl radical (·OH), taken as the most active and aggressive reactive oxygen species (ROS), plays an important role in cell redox regulation and ferroptosis processes. It is a great challenge to develop methods for highly selective and sensitive detection and imaging of ·OH. A new near-infrared (NIR) fluorescence probe Probe-HMP was designed and synthesized by introducing 3-methylpyrazolone as the specific recognition moiety to the hemicyanine backbone of the NIR fluorophore AXPI-NH₂, which formed with the hydrazine group. Probe-HMP exhibited excellent detection performance in vitro, such as instantaneous response, low detection limit of 24 nM, and excellent selectivity without the interference from other ROS. Based on the actions of ·OH promoter phenylmercuric acetate (PMA) and ·OH scavenger 4-hydroxy-TEMPO (Tempol), Probe-HMP was successfully applied to obtain images of endogenous ·OH in HepG2 cells, Arabidopsis thaliana, and mice. The results show that Probe-HMP can stably and efficiently image endogenous ·OH, the fluorescence intensity of the experimental group incubated with PMA was higher than that of the control group incubated with Probe-HMP only, and a significant decrease could be observed in the inhibitor group incubated with Tempol. More importantly, Probe-HMP can achieve the detection of endogenous ·OH in HepG2 cells during ferroptosis by using erastin and deferoxamine mesylate (DFO) to induce or inhibit ferroptosis, revealing that the fluorescence intensity change of Probe-HMP was caused by ·OH generated and ferroptosis is accompanied by significant ·OH generation. The excellent performance of Probe-HMP makes it a promising candidate for exploring the physiological and pathological processes associated with ferroptosis.

Cysteine (Cys), as one of the biological thiols, is related to many physiological and pathological processes in humans and plants. Therefore, it is necessary to develop a sensitive and selective method for the detection and imaging of Cys in biological organisms. In this work, a novel near-infrared (NIR) fluorescent probe, Probe-Cys, was designed by connecting furancarbonyl, as a new recognition moiety, with Fluorophore-OH via the decomposition of IR-806. The use of the furan moiety is anticipated to produce more effective fluorescence quenching because of the electron-donating ability of the O atom. Probe-Cys has outstanding properties, such as a new recognition group, an emission wavelength in the infrared region at 710 nm, a linear range (0-100 μM), a low detection limit of 0.035 μM, good water solubility, excellent sensitivity, and selectivity without the interference of Hcy, GSH, and HS^-. More importantly, Probe-Cys could achieve the detection of endogenous Cys by reacting with the stimulant 1,4-dimercaptothreitol (DTT) and the inhibitor N-ethylmaleimide (NEM) in HepG2 cells and zebrafish. Ultimately, it was successfully applied to obtain images of Arabidopsis thaliana, revealing that the content of Cys in the meristematic zone was higher than that in the elongation zone, which was the first time that the NIR fluorescence probe was used to obtain images of Cys in A. thaliana. The superior properties of the probe exhibit its great potential for use in biosystems to explore the physiological and pathological processes associated with Cys.

A new fluorescent probe, namely 3-oxo-3H-phenoxazin-7-yl dimethylcarbamate to the detection of acetylcholinesterase and butyrylcholinesterase in vitro and in vivo.

Formaldehyde (FA), the smallest molecular aldehyde with strong reducing properties, could regulate body homeostasis endogenously during physiological and pathological processes. The effective near-infrared (NIR) fluorescent probe is needed as a visualizer of FA in biologic organisms. In this work, a novel NIR fluorescent Probe-NHNH₂ was designed on the basis of Probe-NH₂ via introducing a strong nucleophilic hydrazine group, which can be used as a quenching and recognizing moiety for the detection of FA. With the treatment of FA, the hydrazine group of Probe-NHNH₂ undergoes condensation and achieves a turn-on NIR fluorescence signal at a wavelength of 706 nm. The spectroscopic performance of Probe-NHNH₂ for FA was evaluated, and it exhibited high sensitivity and selectivity for the detection of FA in solution. Moreover, compared to the amine moiety-based Probe-NH_2, which our group reported, we found that hydrazine moiety-based Probe-NHNH₂, exhibited a better reaction time of within 10 min and a lower detection limit of 0.68 μM, reflecting that the reaction of FA with hydrazine moiety is faster and more sensitive than that of FA with the amino group. More importantly, Probe-NHNH₂ was successfully applied to real-time imaging of endogenous FA by reacting with effective stimulant tetrahydrofolate and scavenger sodium bisulfite in zebrafish and mice. It is expected that we can provide a new rapid, sensitive NIR fluorescence theoretical basis for FA detection and in vivo imaging applications.