•A novel AuNP-based sensor for meat/fish spoilage is developed.•The sensor detects dimethyl sulfide at 0.5 ppm and histamine at 0.035 ppm.•The sensor exhibits excellent selectivity for the markers of ...interest.•A sequential and positive causative statistic model of the detection is established.
A colorimetric probe based on gold nanoparticles (AuNPs) which is sensitive to two important volatile biogenic markers, i.e., dimethyl sulfide and histamine, is developed to monitor the spoilage of raw meat, fish, crustaceans, and preserved meat. The colorimetric detection is attributed to the transformation of the non-aggregated form of AuNPs to its aggregated form upon binding of the biomarkers. The AuNPs enable the detection of dimethyl sulfide and histamine at limits of 0.5 and 0.035 μg/mL, respectively. Furthermore, the probe exhibits excellent selectivity for those markers in the presence of other volatiles commonly generated by spoiled real meat and seafood. A sequential and positive causative relationship is exhibited among the storage period, the total bacteria count, the DMS evolved, and the chemosensing signal generated. Thus, this probe serves as a nondestructive and cost-effective detector for the real-time monitoring of meat spoilage.
The catalytic chemosensing assay (CCA), a new indicator displacement assay, was developed for selective detection of methomyl, a highly toxic pesticide. Trimetallic complex ...{FeII(dmbpy)(CN)4‐PtII(DMSO)Cl2‐RuII(bpy)2(CN)2} (1; dmbpy=4,4′‐dimethyl‐2,2′‐bipyridine, bpy=2,2′‐bipyridine) was synthesized as a task‐specific catalyst to initially reduce and degrade methomyl to CH3SH/CH3NH2/CH3CN/CO2. The thus‐produced CH3SH interacts with the trimetallic complex to displace the cis‐RuII(bpy)2(CN)2 luminophore for monitoring. Other pesticides, including organophosphates and similar carbamate pesticides, remained intact under the same catalytic conditions; a selective sensing signal is only activated when 1 recognizes methomyl. Furthermore, 1 can be applied to detect methomyl in real water samples. In the luminescent mode of the assay, the method detection limit (MDL) of 1 for methomyl (LD50=17 mg kg−1) was 1.12 mg L−1.
Detect and degrade: The catalytic chemosensing assay (CCA), a new indicator displacement assay, was developed for selective detection of organopesticides in tap and underground water samples. Thus, trimetallic complex {FeII(dmbpy)(CN)4‐PtII(DMSO)Cl2‐RuII(bpy)2(CN)2} (1; dmbpy=4,4′‐dimethyl‐2,2′‐bipyridine, bpy=2,2′‐bipyridine), integrates a catalyst (FeII(dmbpy)(CN)42−), a signaling transducer (RuII(bpy)2(CN)2), and two receptors (PtII(DMSO)Cl−) to simultaneously detect and degrade the pesticide methomyl.
Herein, a catalytic chemosensing assay (CCA), based on a bimetallic complex, RuII(bpy)2(CN)22(CuII)2 (bpy=2,2′‐bipyridine), is described. This complex integrates a task‐specific catalyst ...(CuI‐catalyst) and a signaling unit (RuII(bpy)2(CN)2) to specifically hydrolyze methyl parathion, a highly toxic organophosphate (OP) pesticide. The bimetallic complex catalyzed the hydrolysis of the phosphate ester to generate o,o‐dimethyl thiophosphate (DTP) anion and 4‐nitrophenolate. Intrinsically, 4‐nitrophenolate absorbed UV/Vis light at λmax=400 nm, creating the first level of the chemosensing signal. DTP interacted with the original complex to displace the chromophore, RuII(bpy)2(CN)2, which was monitored by spectrofluorometry; this was classified as the second level of chemosensing signal. By integrating both spectroscopic and spectrofluorometric signals with a simple AND logic gate, only methyl parathion was able to provide a positive response. Other aromatic and aliphatic OP pesticides (diazinon, fenthion, meviphos, terbufos, and phosalone) and 4‐nitrophenyl acetate provided negative responses. Furthermore, owing to the metal‐catalyzed hydrolysis of methyl parathion, the CCA system led to the detoxification of the pesticide. The CCA system also demonstrated its catalytic chemosensing properties in the detection of methyl parathion in real samples, including tap water, river water, and underground water.
Combining catalyst and chemosensor: Herein, a bimetallic complex, RuII(bpy)2(CN)22(CuII)2 (bpy=2,2′‐bipyridine), integrating a catalyst (CuI‐catalyst) and a signaling transducer (RuII(bpy)2(CN)2) to simultaneously detect and degrade methyl parathion, is presented. The catalytic chemosensing assay (CCA) constitutes an “AND” logic gate for organophosphate detection in tap, river, and underground water samples.
•A surface molecularly imprinted polymer (PS-co-PMAA@VSMIP) was prepared.•A hollow structured surface molecularly imprinted polymer (HVSMIP) was prepared.•Both PS-co-PMAA@VSMIP and HVSMIP were ...visible-light-responsive.•HVSMIP performed better than PS-co-PMAA@VSMIP for chlorpyrifos analyte.•HVSMIP was applied to detect trace chlorpyrifos in spiked apple and carrot samples.
A visible-light-responsive azobenzene derivative, 3,5-dichloro-4-((2,6-dichloro-4-(methacryloyloxy)phenyl)diazenyl)benzoic acid, was synthesized and used as the functional monomer to fabricate a visible-light-responsive core-shell structured surface molecularly imprinted polymer (PS-co-PMAA@VSMIP). After removal of the sacrificial PS-co-PMAA core, a hollow structured surface molecularly imprinted polymer (HVSMIP) was obtained. Both the PS-co-PMAA@VSMIP and HVSMIP were used for the detection of chlorpyrifos, a moderately toxic organophosphate pesticide. They exhibited good visible-light-responsive properties (550 nm for trans→cis and 440 nm for cis→trans isomerization for an azobenzene chromophore) in ethanol/water (9:1, v/v). Compared with the PS-co-PMAA@VSMIP, the HVSMIP had a larger surface area, pore volume, binding capacity, imprinting effect, maximum chemical binding capacity, dissociation constant, and photo-isomerization rate. The HVSMIP was applied to detect trace chlorpyrifos in fruit and vegetable samples. This was achieved by measuring the trans→cis rate constant of the HVSMIP in the sample solution, with good recoveries, low relative standard deviations, and a low detection limit.
A new RNA-selective fluorescent dye integrated with a thiazole orange and a p-(methylthio)styryl moiety shows better nucleolus RNA staining and imaging performance in live cells than the commercial ...stains. It also exhibits excellent photostability, cell tolerance, and counterstain compatibility with 4',6-diamidino-2-phenylindole for specific RNA-DNA colocalization in bioassays.
This paper describes the chemosensing and catalytic amplification properties of MnIII(TPP)(NCS)–PdII(DMSO)Cl2 (1, TPP = 5,10,15,20-tetraphenyl-21H,23H-porphine) for detecting the organophosphate ...pesticide dimethoate. Complex 1 selectively detects dimethoate, resulting in a visual color change from yellowish-brown to green with a UV–vis spectroscopic method detection limit (MDL) of 22.7 μM. This selectivity is attributed to the formation of a more stable PdII(dimethoate)2Cl2 adduct, resulting in the release of the colored MnIII(TPP)(NCS) unit from complex 1. Interestingly, the free PdII(dimethoate)2Cl2 released acts as a catalyst for the Heck coupling reaction of 5-diethylamino-2-iodo-phenyl ester (2), producing the highly fluorescent 7-diethylaminocoumarin (3). This catalytic process results in significant signal amplification, enhancing the original sensitivity by 25 times, with a spectrofluorimetric MDL of 0.9 μM. The proposed indicator-catalyst displacement assay successfully quantifies dimethoate concentrations in natural water samples, exhibiting good recoveries (92.5–108.1%) and low relative standard deviations (1.2–6.2%).
Display omitted
Indicator-catalyst displacement assay This study reveals the remarkable synergy between a catalyst and indicator in a displacement assay. A novel bimetallic complex, MnIII(TPP)(NCS)–PdII(DMSO)Cl2 (1), is synthesized for detecting organophosphate pesticides. Upon dimethoate exposure, a displacement reaction occurs, triggering a distinct color change. The activated catalyst, PdII, exhibits impressive 25-fold signal amplification, greatly enhancing detection sensitivity with a spectrofluorimetric method, achieving a low detection limit of 0.9 μM.
The detection of neutral biogenic amines plays a crucial role in food safety. Three new heterobimetallic Ru(II)-Ln(III) donor-acceptor complexes, KPrRu, KNdRu, and KSmRu, ...K{Ru((II))((t)Bubpy)(CN)42-Ln((III))(H2O)4} (where (t)Bubpy = 4,4'-di-tert-butyl-2,2'-bipyridine), have been synthesized and characterized. Their photophysical and X-ray crystallographic data were reported in this study. These complexes were found to be selective for biogenic amine vapors, such as histamine, putrescine, and spermidine, with a detection limit down to the ppb level. The sensitivities of these complexes to the amines were recorded as ~log K = 3.6-5.0. Submicron rods of the complexes, with a nanoscale diameter and microscale length, were obtained through a simple precipitation process. Free-standing polymeric films with different degrees of porosity were fabricated by blending the submicron rods with polystyrene polymer. The polymer with the highest level of porosity exhibited the strongest luminescence enhancement after amine exposure. Real time monitoring of gaseous biogenic amines was applied to real fish samples (Atlantic mackerel) by studying the spectrofluorimetric responses of the Ru(II)-Ln(III) blended polymer film.
Plastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain ...plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C−C/C−H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic‐waste problems.
Plastic wastes to carboxylic acids: The new technology provided herein, combining chemical activation by sulfonation and the Fenton degradation, leads to the conversion of inert polyethylene plastic waste into useful high‐value fine chemicals, such as carboxylic acids, under ambient conditions.
