Fluorescent and Colorimetric Ionic Probe Based on Fluorescein for the Rapid and On-Site Detection of Paraquat in Vegetables and the Environment

A highly sensitive fluorescent probe based on functionalised ionic liquids for timely detection of trace Hg2+ and CH3Hg+ in food

A novel fluorescent probe was fabricated using fluorescein-based ionic liquids (ILs) to effectively achieve rapid and accurate detection of Hg2+ and CH3Hg+ in food. A probe developed by addition of modified fluorescein into the functionalised ILs presented a promising sensitivity toward Hg2+ and CH3Hg+ at concentrations of 0.4 and 60 nM, respectively. In addition, the novel probe could achieve visual and timely detection of Hg2+ and CH3Hg+ by the naked eyes at concentrations of 0.1 and 1 μM, respectively. The probe could also overcome the interference of potential ions and common organic ligands and detect Hg2+ and CH3Hg+ in real food samples, such as green tea and liquor. The probe could be converted into a paper-based sensor to visually detect Hg2+ and CH3Hg+ at levels as low as 10 nM.

An ion synergism fluorescence probe via Cu2+ triggered competition interaction to detect glyphosate

The widespread use of glyphosate (Gly) poses significant risks to environmental and human health, underscoring the urgent need for its sensitive and rapid detection. In this work, we innovated by developing a novel material, ionic liquids, which formed the ionic probe "[P66614]2[2,3-DHN]-Cu2+ (PDHN-Cu2+)" through coordination with Cu2+. This probe capitalized on the distinctive fluorescence quenching properties of ionic liquids in the presence of Cu2+, driven by synergistic interactions between anions and cations. Glyphosate disrupted the PDHN-Cu2+ coordination structure due to its stronger affinity for Cu2+, triggering a "turn-on" fluorescence response. Impressively, PDHN-Cu2+ enabled the sensitive detection of glyphosate within just one minute, achieving a detection limit as low as 71.4 nM and excellent recovery rates of 97-103% in diverse samples. This groundbreaking approach, utilizing ionic probes, lays a robust foundation for the accurate and real-time monitoring of pesticides, employing a strategy based on synergism and competitive coordination.

A fluorescence ionic probe utilizing Cu2+ assisted competition for detecting glyphosate abused in green tea

Food fraud caused by the violation of glyphosate use in tea is frequently exposed, posing a potential health risk to consumers and undermining trust in food safety. In the work, an ionic fluorescent probe "[P66614] [4HQCA]-Cu2+ (PHQCA-Cu2+)" was constructed using Cu2+ and ionic liquids coordination through a competitive coordination strategy to detect glyphosate. This probe exhibited a prominent "turn-on" fluorescence response in glyphosate detection. PHQCA-Cu2+was destroyed by glyphosate with its strong coordination capability, and a new complex re-formed simultaneously between glyphosate and the Cu2+ in it, where Cu2+ served as an "invisible indicator" influencing fluorescence changes. Remarkably, PHQCA-Cu2+formed rapidly within 5 s, demonstrated exceptional sensitivity and selectivity, and satisfactory detection performance on paper strips impregnated withPHQCA-Cu2+.Importantly,PHQCA-Cu2+showed excellent recoveries in various green tea, which offered a viable method for identifying contaminated products from the supply chain quickly to enhance overall food safety surveillance.

Research progress of microfluidics-based food safety detection

High demands for food safety detection and analysis have been advocated with people's increasing living standards. Even though numerous analytical testing techniques have been proposed, their widespread adoption is still constrained by the high limit of detection, narrow detection ranges, and high implementation costs. Due to their advantages, such as reduced sample and reagent consumption, high sensitivity, automation, low cost, and portability, using microfluidic devices for food safety monitoring has generated significant interest. This review provides a comprehensive overview of the latest microfluidic detection platforms (published in recent 4 years) and their applications in food safety, aiming to provide references for developing efficient research strategies for food contaminant detection and facilitating the transition of these platforms from laboratory research to practical field use.

A Portable Array Visualization Device Integrating Sample Preparation and Detection All-in-One for the On-Site Analysis of Complex Samples

A gas membrane separation/array fluorescence visualization (GMS/AFV) device is developed by integrating hydrazine-based carbonized copolymer dots (PD-N2H4) for visual on-site analysis. The novel PD-N2H4 was synthesized using a "polymer template" approach, exhibiting strong blue fluorescence capable of visual sensing. The GMS/AFV device integrates sample preparation and detection all-in-one, consisting of a smartphone, a sample pretreatment system, and an optical system. In the detection procedure, the samples will be treated in the sample pretreatment system to create volatile gases. Therefore, any gas samples as well as solid and liquid samples that potentially produce volatile gases can be visually detected on-site by the device. H2S was utilized as a model analyte to test the practicality of the GMS/AFV device. The entire analysis can be finished in 3 min, and the limit of detection of H2S is as low as 3.4 μg/L. Surprisingly, the device is also capable of high-throughput sample detection, which can process 48 samples simultaneously in about 20 min. The device offers a quick, easy, cheap, and environmentally friendly way to analyze volatile gases, and it creates new opportunities for on-site detection of complex samples.

ZIF-67 based CoS2 self-assembled on graphitic carbon nitride microtubular for sensitive electrochemical detection of paraquat in fruits

Paraquat (PQ) is a widely used and harmful herbicide that must be detected in the environment. This study reports a novel composite (CoS2-GCN) prepared by assembling cobalt disulfide (CoS2) derived from metal-organic frameworks (MOFs) on graphitic carbon nitride (GCN). An electrochemical sensor (CoS2-GCN/ glassy carbon electrode (GCE)) was successfully prepared by modifying CoS2-GCN onto a GCE to sensitively detect PQ. Different concentrations of PQ were detected using square-wave voltammetry, and the CoS2-GCN/GCE electrochemical sensor showed remarkable response signals for PQ in the range of 20 - 1000 nM and 1 - 13 μM, with a detection limit of 4.13 nM (S/N = 3). The CoS2-GCN/GCE electrochemical sensor exhibited high stability, reproducibility, and immunity to interference, which were attributed to the synergistic effects of CoS2 and GCN. In addition, the CoS2-GCN/GCE electrochemical sensor showed high applicability for the analysis of fruit samples. Therefore, the proposed sensor has potential applications in PQ detection.

A portable smartphone platform utilizing dual-sensing signals for visual determination of semicarbazide in food samples

Semicarbazide (SEM) is a metabolite of antibiotic nitrofurazone and a food contaminant in food production, showing potential carcinogenic, mutagenic, teratogenic, and toxic effects on human health. It is urgent to develop a highly efficient and sensitive assay for visual detection of SEM. In this paper, a pyrrolopyrrole cyanine fluorescent probe (PPCy-1) was reported for visualization and quantitative analysis of SEM through a chromophore reaction sensing mechanism for the first time. The probe towards SEM exhibited a fast response (10 min), a low detection limit (0.18 μM), high selectivity, and distinct dual ratiometric fluorescence turn-on and colorimetric modes. Its practicability was further verified by detecting SEM in meat, water, and honey samples with satisfactory recovery values. More importantly, a smartphone-assisted portable testing platform was constructed based on a PPCy-1-immobilized test paper or a polyamide thin film with a color scanning APP for real-time and on-site detection of SEM. This work provides low-cost, convenient, and rapid assays for visual SEM detection, which have potential applications in food safety monitoring.

Design and One-Pot Ultrasound Synthesis of Inorganic Base-Promoted Fluorescent Ligand-Gated Ion Channel Fused Arylpyrazole Sulfonamide Skeletons to Enhance Phloem Mobility and Insecticidal Activity as GABA and nACh Receptors Inhibitors

Ligand-gated ion channels are essential in living organisms, and sulfonamides have antibacterial effects and can be readily coordinated with metal ions with good biological activity. A series of fluorescent ligand-gated ion channel fused arylpyrazole sulfonamide skeletons (APSnM) were synthesized based on a one-pot ultrasound strategy promoted by an inorganic base. APSnM had a high fluorescence quantum yield and a large Stokes shift in ethanol solvent. The ligand bonded ions took on a different color from the ligand and can be used as a probe to detect their own residue on plant surfaces. Their hydrophobic parameters and the fluorescence distribution in Chinese cabbage leaves indicated that APSnM significantly increased the phloem mobility of the plant. The insecticidal activity of APS3Na was higher (LC50 = 7.2423 μg/mL) than that of fipronil (15.2312 μg/mL) against Plutella xylostella, and the mechanism of high insecticidal activity of APS3Na was simulated by molecular docking, which confirmed its strong interactions with the GABA and nACh receptors of Plutella xylostella. Analysis of the crystal structure of these ligand-gated ion channels further confirmed the consistency of their structure and biological activity.