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The ongoing poisoning of agricultural products has pushed the security problem to become an important issue. Among them, exceeding the standard rate of pesticide residues is the main factor influencing the quality and security of agricultural products. Moreover, the abuse of pesticides has introduced a large amount of residues in soil and drinking water, which will enter the food chain to the human body, leading to neurological disorders and cancer. Therefore, great efforts have been devoted to developing fluorescent sensors for detecting pesticide in a facile, quickly, sensitive, selective, accurate manner, which exhibit greater advantages than some traditional methods. In this review, we mainly focus on summarizing the non-biological fluorescent probes for organic pesticides detection with the detection limit of micromole to nanomole, including organic functional small molecules, calixarenes and pillararenes, metal organic framework systems, and nanomaterials. Meanwhile, we described the different sensing mechanisms for pesticides detection of these mentioned fluorescent sensors, the detection limit of each pesticide, the application in detecting actual samples, as well as their respective advantages and development prospects associated with present non-biological fluorescent sensors.

In this study, we have designed and synthesized a novel ‘AND’ logic based fluorescence probe,1-(3′,6′-bis((tert-butyldiphenylsilyl)oxy)-3-oxospiro (isoindoline-1,9′-xanthen)-2-yl)-3-phenylthiourea (FPSi), for the rapid (3 min) simultaneous detection of F− and Hg2+ in DMSO/H2O solution (7:3, v/v). The FPSi probe, synthesized over three steps starting from commercially available fluorescein, was constructed by attaching tert-butyldiphenylsilyl and thiosemicarbazide (as the specific identification groups for F− and Hg2+) to the skeleton of fluorescein, respectively. FPSi produced no fluorescence response towards the addition of F− or Hg2+ separately. However, when the probe was exposed to a solution containing both F− and Hg2+, there was a significant yellow-green fluorescence. FPSi demonstrated an excellent selectivity towards both F− and Hg2+ in the presence of interfering substances. The results of TOF-MS-EI analysis indicated that the response of FPSi towards F− and Hg2+ was mainly aroused by the F− promoted cleavage of Si–O bond, and Hg2+ triggered an irreversible desulfurization reaction leading to the spiral ring opening. Furthermore, the FPSi probe has been successfully used to detect F− and Hg2+ ions in tap water and cropland soil.

The ongoing poisoning of agricultural products has pushed the security problem to become an important issue. Among them, exceeding the standard rate of pesticide residues is the main factor influencing the quality and security of agricultural products. Monitoring pesticide residues and developing simple, yet ultrasensitive detection systems for pesticide residues are urgently needed. In this study, we successfully developed a novel rhodamine derivative as fluorescent and colorimetric chemosensor R-G for the rapid, selective and ultrasensitive detection of glyphosate pesticide residue in aqueous solution. Through a Cu2+-indicator displacement strategy, glyphosate can displace an indicator (R-G) from a Cu2+-indicator complex due to its strong affinity to bind with Cu2+ to give a turn-on fluorescence and distinct color change. Moreover, a test strip was also fabricated to achieve a facile detection of glyphosate pesticide. To demonstrate the possibility of practical applications, glyphosate was detected on the surface of cabbage and in a spiked soil sample. The detection limit of 4.1 nM and the response time of 2 min indicate that the method is enough sensitive and rapid to detect the glyphosate residue at or below levels that pose a health risk.

Hypochlorous acid plays a very important role in living cells, because it can resist microorganism attack and has a lethal effect on pathogens. The unnormal generation of ClO- can cause tissue damage and corresponding diseases. Detection of ClO- is very necessary in biological systems. In this article, we respectively hybridized the two different water-soluble coumarin (7-hydroxycoumarin and 7-diethylaminocoumarin) fluorophores with a longer-wavelength emissive rhodamine fluorophore to construct an intergrant, and then isothiocyanate was modified with the intergrant to recognized ClO-. The two ratiometric fluorescent probes RHClO-1 and RHClO-2 were developed for ClO- detecting with high selectivity and sensitivity. Especially, the probe RHClO-2 has lower detection limit (42 nM) for ClO- in 5 s. What's more, the probe RHClO-2 was successfully used in monitoring endogenous ClO- in living cells.

Electrochemical determination of luteolin and baicalein always needs acidic supporting electrolyte to guarantee good sensitivity. Therefore, most of the reported electrochemical sensors of luteolin and baicalein are unsuitable for detection of neutral actual samples. It is necessary to design a highly sensitive sensor for direct determination of them in neutral conditions. In this study, poly(N-isopropylacrylamide-acrylic acid) hydrogel particles (NIPA/AA) and multiwall carbon nanotubes (MWCNTs) composite modified glassy carbon electrode (GCE) was fabricated by a simple casting method. The voltammetric results showed that the NIPA/AA particle film provided acidic environment for proton-electron coupled reaction in neutral mediums. The near-surface pH of the electrode was related on the loaded amount of the NIPA/AA particles in pH range from 4.2 to 5.9. The voltammetric behaviors of luteolin and baicalein at the NIPA/AA-MWCNTs-GCE were studied by cyclic voltammetry. The peak separations between cathodic and anodic peaks were decreased and peak currents were increased because of decrease in pH and increase in ion conductivity at the local electrode surface. The sensitivity of the electrode was investigated by differential pulse voltammetry. Even under neutral conditions, the plots of the oxidation currents of luteolin and baicalein were dependent linearly on their concentration with detection limit of 14.5 pM and 44.4 pM, respectively. Moreover, the proposed NIPA/AA-MWCNTs-GCE was also successfully applied for determination of luteolin and baicalein in peanut shell, Huang-qin and tomato samples.

In this study, we have designed and synthesized a novel 'AND' logic based fluorescence probe,1-(3',6'-bis((tert-butyldiphenylsilyl)oxy)-3-oxospiro (isoindoline-1,9'-xanthen)-2-yl)-3-phenylthiourea (FPSi), for the rapid (3 min) simultaneous detection of F

An Au nanoparticles/poly(caffeic acid) (AuNPs/PCA) composite modified glassy carbon (GC) electrode was prepared by successively potentiostatic technique in pH 7.4 phosphate buffer solution containing 0.02mM caffeic acid and 1.0mM HAuCl4. Electrochemical characterization of the AuNPs/PCA-GC electrode was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical behavior of acetaminophen (AP) at the AuNPs/PCA-GC electrode was also studied by cyclic voltammetry. Compared with bare GC and poly(caffeic acid) modified GC electrode, the AuNPs/PCA-GC electrode was exhibited excellent electrocatalytic activity toward the oxidation of AP. The plot of catalytic current versus AP concentration showed two linear segments in the concentration ranges 0.2-20µM and 50-1000µM. The detection limit of 14 nM was obtained by using the first range of the calibration plot. The AuNPs/PCA-GC electrode has been successfully applied and validated by analyzing AP in blood, urine and pharmaceutical samples.

In this paper, we introduced a new sensor for detecting sulfur mustard (SM) and its simulant through the functionalization of a rhodol chromophore with benzothiazole, followed by thionation of the spirolactam. The synthesized chemodosimeter (RHBT) exhibited an obvious green-yellow fluorescence enhancement and chromogenic change from colorless to fuchsia in the presence of SM and its simulant stimuli, which is based on the spirothiolactam ring opening of rhodol induced by the synergy of S-alkylation of thiolactam and the excited state intramolecular proton transfer (ESIPT) of rhodol-benzothiazole. Furthermore, the chemodosimeter was successfully demonstrated for the rapid detection of SM and its simulant in solution, soil and air at ambient temperature, indicating its potential application for on-site detection of sulfur mustard.