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A series of arecoline derivatives with amino acid moieties were designed and synthesised using an acylamide condensation strategy, taking arecoline as the foundational structure. The insecticidal efficacy of these compounds against Aphis craccivora and Tetranychus cinnabarinus was evaluated. Notably, derivatives 3h and 3i demonstrated superior insecticidal activity compared with arecoline. Additionally, 3h and 3i showed good fungicidal effectiveness against two types of plant fungi. Moreover, molecular docking analyses suggested that 3h and 3i could affect the nervous systems of A. craccivora and T. cinnabarinus by binding to neuronal nicotinic acetylcholine receptors. These findings suggest that compounds 3h and 3i represent promising leads for further development in insecticide and fungicide research. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/B/N codoped hierarchical porous carbon spheres (B-N-Fe-HPCs) were coated onto a gold electrode. • B-N-Fe-HPCs amplified the electrochemiluminescence (ECL) signal of calcein. • The sensor showed very high sensitivity and good selective for the detection of florfenicol. • The sensor had a linear range of 1–8000 × 10−12 mol/L and a detection limit of 4.65 × 10−13 mol/L. Electrochemiluminescence (ECL) signal amplification is an important method for improving sensor sensitivity. In this study, an ECL sensor was developed for florfenicol detection based on the aggregation-induced electrochemiluminescence of calcein and Fe/B/N codoped hierarchical porous carbon spheres (B-N-Fe-HPCs). First, B-N-Fe-HPCs were prepared by a simple high-temperature synthesis method, attached to the gold electrode surface, and used as a signal amplification element. Then, a molecularly imprinted polymer (MIP) was prepared using florfenicol as a template molecule and phthalylenediamine as a functional monomer and doped with calcein on the B-N-Fe-HPC-modified electrode. After the elution of florfenicol, the sensor retains an imprinted site that specifically recognizes florfenicol can readsorb florfenicol in the sample. Because calcein aggregates in the MIP to generate an ECL signal, B-N-Fe-HPCs effectively amplifies this ECL signal. Thus, because the ECL signal of the sensor can be quenched, a new method for detecting florfenicol was established. The sensor used for florfenicol showed very high sensitivity and good selective performance, with a linear range of 1–8000 × 10−12 mol/L and a detection limit of 4.65 × 10−13 mol/L. The sensor was applied to detect actual samples, such as chicken, and the results were satisfactory, with the recovery rate of the spike from 91.2 % to 105.3 %. [ABSTRACT FROM AUTHOR]

The rapid detection of insecticides such as parathion-methyl (PM) requires methods with high sensitivities and selectivities. Herein, a dual catalytic amplification strategy was developed using Fe3O4 nanozyme-supported carbon quantum dots and silver terephthalate metal–organic frameworks (Fe3O4/C-dots@Ag-MOFs) as current amplification elements. Based on this strategy, a novel electrochemical microfluidic paper-based chip was designed to detect PM. Fe3O4/C-dots@Ag-MOFs were synthesised by a hydrothermal method, and a molecularly imprinted polymer (MIP) was then synthesised on the surface of Fe3O4/C-dots@Ag-MOFs using PM as a template molecule. Finally, the reaction zone of a chip was modified with MIP/Fe3O4/C-dots@Ag-MOFs. PM from a sample introduced into the reaction zone was captured by the MIP, which generated a reduction current response at − 0.53 V in a three-electrode system embedded in the chip. Simultaneous catalysis by Fe3O4/C-dots and Ag-MOFs significantly enhanced the signal. The chip had a detection limit of 1.16 × 10−11 mol L−1 and was successfully applied to the determination of PM in agricultural products and environmental samples with recovery rates ranging from 82.7 to 109%, with a relative standard deviation (RSD) of less than 5.0%. This approach of combining a dual catalytic amplification strategy with an MIP significantly increased the sensitivity as well as selectivity of chips and can potentially be used to detect a wide variety of target analytes using microfluidic paper-based chips. [ABSTRACT FROM AUTHOR]

A luminescent double recognition nanoprobe is described as a new strategy for the selective determination of chiral molecules. C-dots/Ir/Au fluorescent nanoparticles, synthesised under hydrothermal conditions, are used as a high-performance probe in combination with a molecularly imprinted polymer (MIP) and calix[6]arene as a double recognition element. Thiolated calix[6]arene is grafted on C-dots/Ir/Au as the first recognition element, which then forms a host–guest complex with the target molecule levodopa (L-DOPA). Subsequently, an MIP is prepared on the C-dots/Ir/Au (MIP/C-dots/Ir/Au) by chemical polymerisation. After the removal of L-DOPA, double recognition imprinting cavities are formed. The fluorescence intensity at 478 nm of the nanoprobe is effectively quenched by adsorption of L-DOPA on MIP/C-dots/Ir/Au, which provides a method for L-DOPA determination. Owing to the double recognition strategy, this method has excellent selectivity which can effectively avoid interference from enantiomer D-DOPA, and a imprinting factor of 7.1 is obtained for L-DOPA. This accurate and reliable method, with a wide linear range (5 × 10−10 to 1.2 × 10−7 mol L−1) and a low limit of detection (1.45 × 10−10 mol L−1), was successfully applied to the determination of L-DOPA in real samples, giving standard recoveries of 89.7–110.0%. Thus, the proposed sensing method provides a viable approach for the determination of a single enantiomer. [ABSTRACT FROM AUTHOR]

Schematic presentation of the sensor for the detection of CFX. [Display omitted] • An electrochemiluminescence sensor for ciprofloxacin determination was developed. • Aggregation-induced luminescence and nanozyme amplification enhanced sensitivity. • A molecularly imprinted polymer provided selectivity. • A linear detection range of 2–3000 pM was achieved with detection limit of 0.598 pM. To broaden the applicability of electrochemiluminescence (ECL) sensors toward the sensitive and selective detection of trace antibiotic residues, new ECL reagents are required. Herein, a novel molecularly imprinted sensor based on an aggregation-induced ECL reagent was fabricated for the sensitive detection of ciprofloxacin (CFX). A covalent organic framework with aggregation-induced ECL (COF-AIECL) was synthesised using a boric acid condensation dehydration reaction. Then, an electrode surface was modified with COF-AIECL as a signal element and nanozymatic ferriferrous oxide@platinum nanoparticles (Fe 3 O 4 @Pt NPs) as a signal amplification element. Subsequently, using CFX as a template molecule, a molecularly imprinted polymer (MIP) was fabricated on the modified electrode. The ECL signal of COF-AIECL was catalytically amplified by the Fe 3 O 4 @Pt NPs, whereas CFX effectively quenched this signal. Consequently, the ECL signal was controlled by CFX elution from and adsorption by the MIP, thus establishing a new method for CFX detection. The sensitivity of the sensor was greatly enhanced by the aggregation-induced luminescence effect and nanozyme amplification, whereas the MIP effectively improved the selectivity for CFX. Under optimal conditions, the electrochemical sensor exhibited a linear detection range of 2 × 10−12 to 3 × 10−9 mol L−1, with a detection limit of 5.98 × 10−13 mol L−1. Furthermore, in untreated milk samples, CFX recoveries of 92.0%–111% were achieved. Thus, the developed sensor exhibited good reproducibility, stability, and selectivity for CFX detection. [ABSTRACT FROM AUTHOR]

A highly sensitive kanamycin electrochemiluminescence (ECL) switch sensor was constructed. A signal element consisting of ordered mesoporous carbon loaded with indium oxide nanoparticles/carbon quantum dots (OMC/In2O3/C-dots) was assembled on the surface of a gold electrode. Then, a molecularly imprinted polymer (MIP) was prepared on the modified electrode surface using kanamycin as the template molecule and o-aminophenol as the functional monomer. After kanamycin elution, the prepared sensor retained specific kanamycin recognition sites. OMC/In2O3 effectively amplified the ECL signal of the C-dots, thereby enhancing the detection sensitivity, whereas kanamycin quenched the signal. Therefore, the imprinted sites acted as a switch, providing a new method for detecting kanamycin. Under the optimal experimental conditions, the concentration of kanamycin was proportional to the degree of ECL quenching within a linear range of 5–4500 × 10−12 mol L−1 at 0.8 V (vs. Ag/AgCl electrode electrode), and the detection limit was 5.8 × 10−13 mol L−1. When applied to the detection of kanamycin in actual samples, such as chicken, duck, pork, and milk, the recovery for spiked samples was in the range 92.7–110%. [ABSTRACT FROM AUTHOR]

• The sensor detection method for ethephon based on molecularly imprinted switch was established for the first time. • Au NPs-amplification effect was proposed in the sensor to improve sensitivity. • This sensor can be used as a general strategy to detect other target molecules. A highly sensitive molecularly imprinted ethephon sensor based on the amplification effect of gold nanoparticle (Au NPs) was designed in this study. An ethephon molecularly imprinted polymer (MIP) was prepared on a surface by electropolymerisation with Au NPs as the carriers and ethephon as the template molecule. Elution of the template molecule gave an MIP sensor that retains imprinted sites for specific recognition of ethephon. The sensor forms a current switch through adsorption of different concentrations of ethephon molecules to obtain different current responses, thereby establishing a new method for ethephon detection. The results indicated that using Au NPs as a carrier in the ethephon imprinted sensor could permit the loading of more MIP and increase the electron-transfer rate. The sensitivity of the sensor prepared with Au NPs was increased by three orders of magnitude compared to conventional MIP sensors without a carrier. Using potassium ferricyanide as a probe, the oxidation peak intensity of the probe molecule and the negative logarithm of the ethephon concentration exhibited a linear relationship within the concentration range from 1.0 × 10−13 to 1.0 × 10−9 mol L−1. The linear equation was ΔI (10−5 A) = −1.7838 × (−lg c) + 26.1216, and the detection limit was 2.78 × 10−14 mol L−1. In addition, the sensor successfully measured the ethephon content in apples. [ABSTRACT FROM AUTHOR]

Highly-conductive two-dimensional covalent organic framework (COF) displays prominent applications in various fields of science and technology. This paper reports the design and liquid-liquid interface synthesis of a novel Zr-coordinated amide porphyrin-based 2D COF (Zr-amide-Por-based 2D COF). The COF adopts a graphene-like multilayer structure with the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) band gap of 1.6 eV. The ordered multilayer structure of the amide COF was confirmed through a series of characterization techniques, including scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In particular, the inherent-ordered structure of Zr-amide-Por-based 2D COF with Zr as the catalytically active center confers several distinct advantages to the material, such as high conductivity and high electrocatalysis performance. A molecularly imprinted tetracycline electrochemiluminescence sensor was constructed based on the Zr-amide-Por-based 2D COF, and gate control effect was used as a signal-generation mechanism. Under optimal conditions, the sensor showed a good linear relationship with tetracycline in the concentration range of 5–60 pM, with a detection limit of 2.3 pM. Because the sensor is rapid, cost-efficient, highly sensitive, and specific, it can be considered as a viable platform for veterinary drug residue monitoring. A molecularly imprinted tetracycline electrochemiluminescence sensor was constructed based on the efficient catalysis of Zr-coordinated amide porphyrin-based 2D COF on hydrogen peroxide. Image 1 • A amide 2D COFs was synthesized by liquid-liquid interfacial polymerization. • The prepared COFs with good conductivity and high catalytic activity were confirmed. • A tetracycline molecularly imprinted ECL sensor was constructed based on COFs. • The pM level of tetracycline was analyzed by the constructed sensor. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) exhibit excellent photoelectrically active structures and serve as channels for photon capture and charge carrier transport. However, their relatively high charge-carrier recombination rates and lack of specific recognition sites limit their application in photoelectrochemical sensing. This paper reports a functionalized donor–acceptor (D-A) COF comprising electron-rich polycyclic aromatic moieties and electron-deficient triazines (Tz) incorporating boronic acid through ligand exchange. The number of aromatic rings in the polycyclic aromatic moiety is crucial for establishing an efficient D-A system within COF. In the absence of an external electron donor, the anthracene-based COF exhibited a five-fold enhancement in photocurrent compared to the naphthalene-based COF. The resulting anthracene-based D-A COF exhibited enhanced orbital overlap and electron push–pull interactions, facilitating more effective charge separation. Furthermore, introducing boronic acid enabled the selective enrichment of low-concentration external electron donors, such as dopamine, in the inner Helmholtz plane. This ingenious approach establishes a unique dual-channel D-A system that allows direct measurement of dopamine in serum. Under optimized conditions, the test platform achieves good correspondence for dopamine at 1 to 100 nM and 0.5 to 100 μM with a detecting limit of 0.36 nM (3σ/S, n = 11). This strategy introduces a novel dimension to photoelectrochemical sensing, focusing on the effect of spatial separation between the external electron donor and the photoelectrode interface that intricately shapes the behavior and enhances the performance of the photoelectric system. A boric acid functionalized dual channel D-A COF by incorporating a condensed aromatic hydrocarbon as the electron donor moiety and triazine as the electron acceptor have been synthesized and successfully applied in specific sensing of trace dopamine in serum. [Display omitted] [ABSTRACT FROM AUTHOR]

The performance of an electrochemiluminescent reagent directly affects the performance of its corresponding electrochemiluminescent (ECL) sensor. In this study, Fe/Zn-benzene-1,3,5-tricarboxylic acid metal–organic framework@C-dots (Fe/Zn-BTC@C-dots), which consist of a nano-loaded carbon quantum dot material with an excellent luminescence performance, were synthesised for the first time. Subsequently, they were used to modify the surface of a glassy carbon electrode, and combined with a single-chain thiamethoxam DNA aptamer to construct a biosensor. A novel method for the detection of thiamethoxam was established based on control of the excellent luminescence signal of the Fe/Zn-BTC@C-dots by specific recognition of the aptamer by the target molecule (a signal switch). Upon capturing thiamethoxam, the electrochemical luminescence intensity of the sensor was quenched. The ability of Fe/Zn-BTC to effectively catalyse and amplify the electrochemical luminescence of the C-dots significantly improved the sensitivity of the sensor, while the specific recognition of the target by the aptamer imparted the sensor with an excellent selection ability. Such an advanced approach is promising for the detection of thiamethoxam, with a linear range of 5–5000 × 10−11 mol/L and a sensitivity of 9.81 × 10−12 mol/L being achieved. Moreover, the sensor exhibited recovery rates of 90.5–109.3% upon the detection of thiamethoxam in actual samples. [Display omitted] • Fe/Zn-BTC@C-dot composites were prepared to construct an ECL sensor. • This DNA-adapted sensor was applied in the sensitive detection of thiamethoxam. • The sensor exhibited a remarkable reproducibility, selectivity, and stability. [ABSTRACT FROM AUTHOR]

The key to developing sensors for chiral drug determination is to exclude interference from enantiomers. In this study, metal–organic frameworks (MOFs) and molecularly imprinted polymer (MIP) were introduced to prepare a chiral sensor for levofloxacin detection. The MIP was electropolymerised on the surface of the Cu/Fe-benzene-1,3,5-tricarboxylate MOF (Cu/Fe-BTC)-modified Au electrode using levofloxacin as a template molecule. After eluting the levofloxacin, a chiral sensor with recognition sites for levofloxacin was obtained. With this site as a switch, a novel method for detecting levofloxacin was established. Because of the enhanced recognition effect, the sensor can effectively exclude the enantiomeric interference of d-ofloxacin. Moreover, Cu/Fe-BTC can effectively amplify the current response signal and improve the sensitivity of the sensor. The linear range of the sensor was 5 to 4000 × 10−11 mol L−1, and the detection limit was 2.07 × 10−11 mol L−1. When applied to detecting levofloxacin in actual samples, the sensor showed a 92.7–109.8% recovery. [ABSTRACT FROM AUTHOR]

The use of dual recognition and multiple detection modes is an attractive strategy for realising sensors with improved selectivity and accuracy. Herein, a molecularly imprinted polymer (MIP)-based sensor is developed for amoxicillin detection based on two detection modes (fluorescence and electrochemiluminescence) and dual recognition. First, graphene oxide loaded with CdTe quantum dots/gold nanoparticles (GO/CdTe/Au NPs) is coated onto an indium tin oxide (ITO) electrode. Then, 4-mercapto-calix[6]arene is bonded to GO/CdTe/Au NPs as the first recognition element, which then form a host–guest complex with the target molecule amoxicillin. Subsequently, as the second recognition element, an MIP is prepared on the ITO electrode. After amoxicillin is removed from the MIP, specific identification sites for amoxicillin are obtained. Furthermore, the GO/CdTe/Au NPs can generate fluorescence and electrochemiluminescence signals that are effectively quenched by amoxicillin. Therefore, on/off switching of these signals can be achieved through the elution or adsorption of amoxicillin. The dual detection modes are complementary and provide mutual authentication, which can improve the detection accuracy and application scope. Moreover, the dual recognition sites for amoxicillin, improve detection selectivity. The fluorescence and electrochemiluminescence modes have detection ranges of 5–1000 × 10−11 mol L−1 and 5–1500 × 10−11 mol L−1, respectively, with detection limits of 9.2 × 10−12 mol L−1 and 8.3 × 10−12 mol L−1, respectively. Image 1 • An amoxicillin sensor is fabricated based on two detection modes, with GO/CdTe/Au NPs used as an optical element. • Dual fluorescence and electrochemiluminescence detection modes improve accuracy. • Dual recognition sites (4-mercapto-calix[6]arene /molecularly imprinted polymer) impart selectivity. [ABSTRACT FROM AUTHOR]

A fluorometric assay is described for the determination of Cd(II) in environmental and agricultural samples. It is making use of a molecularly imprinted polymer (MIP) and aptamer as dual recognition units, while carbon quantum dots (co-doped with sulphur and nitrogen) and gold nanoparticles (SN-CQD/Au) act as the fluorophores. The aptamer-modified MIP was placed on an SN-CQD/Au-modified indium tin oxide glass electrode. Cd(II) was detected with high selectivity by the recognition sites of the aptamer in the MIP. Fluorescence, with excitation/emission peaks at 370/430 nm, is quenched by Cd(II). Response is linear in the 20 pM to 12 nM concentration range. The detection limit is 1.2 pM. The sensor is selective for Cd(II), and recoveries from spiked waters, soils and vegetables real-world samples range between 82.1 and 113.9%. [ABSTRACT FROM AUTHOR]

A photoelectrochemical sensing platform based on ligand-variable metal clusters charge transfer was established for the quantitative assay of ronidazole (RNZ) using Ce-porphyrin-metal–organic frameworks/silver nanowires (Ce-Por-MOFs/AgNWs). Rod-like Ce-Por-MOFs and well-dispersed sub-50 nm AgNWs were prepared using a hydrothermal method and polyol strategy, and then through simple drop coating to yield Ce-Por-MOFs/AgNWs nanocomposites. We investigated the intrinsic semiconducting properties of the composites. More importantly, it was found that the variable-valence metal node can provide electronic defect states similar to those caused by multi-metal doping, synergizing with the surface plasmon effect of AgNWs, which significantly improved the photoelectric conversion efficiency, thereby resulting in excellent optoelectronic properties. In combination with molecular imprinting, a competitive type trace photoelectrochemical sensor for RNZ was constructed using Fe2+ as the electron donor and probe. Under optimal conditions, the sensor response is proportional to the logarithm of RNZ concentration in the range 0.1–104 nM with a detected limit of 0.038 nM. The recoveries ranged from 87.2 to 116% with relative standard deviations (RSDs) < 6.5% (n = 3) in milk sample. This work reveals the charge-transfer process of variable-valence metal nodes in MOFs during photoelectrochemical processes, which will provide new insights for the sensing application of variable-valence metal MOFs. [ABSTRACT FROM AUTHOR]

In this work a simple, rapid, and environmentally friendly method has been established for the determination of chlorpyrifos residue in green tea by dispersive liquid–liquid microextraction and gas chromatography-flame photometric detection. Some experimental parameters that influence extraction efficiency, such as the kind and volume of disperser solvents and extraction solvents, extraction time, addition of salt and pH, were investigated. And the optimal experimental conditions were obtained, quantitative analysis was carried out using external standard method. The correlation coefficient of the calibration curves was 0.999 with in 0.05 mg/kg to 5 mg/kg. The results showed that under the optimum conditions, the enrichment factors of the chlorpyrifos was about 554.51, the recoveries for standard addition fell in the range from 91.94 to 104.70% and the relative standard deviations was 4.61%. The limit of quantification of chlorpyrifos in green tea was 0.02 μg/mL at the signal/noise ratio of 3. [ABSTRACT FROM AUTHOR]

Considering the limitations associated with existing methods for the detection of trace amounts of trichlorfon, this paper proposes a novel molecularly imprinted electrochemiluminescence (ECL) sensor for the detection of trichlorfon by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes (MWCNTs/Ag NPs) in a luminol–H2O2 ECL system. Here, trichlorfon was electropolymerized on the surface of the MWCNT/Ag NP–modified gold nanoelectrode with o-phenylenediamine to prepare the molecularly imprinted polymer-based sensor. After eluting the trichlorfon, imprinted holes for the identification of trichlorfon were retained on the sensor, which were used as signal switches to obtain different ECL intensities through the adsorption of different concentrations of trichlorfon. The ECL signal of the sensitized luminol–H2O2 was doubly enhanced by the MWCNTs/Ag and trichlorfon, improving the sensitivity of the sensor. The trichlorfon concentration was positively correlated with the enhanced ECL intensity of the sensor in the range 5.0 × 10−8–5.0 × 10−11 mol L−1, and the detection limit of trichlorfon was 3.9 × 10−12 mol L−1. Moreover, the proposed sensor was successfully applied to the detection of trichlorfon residues in real samples, and the recovery ranged between 91.8 and 109%. A molecularly imprinted electrochemiluminescence sensor for trichlorfon detection by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes in a luminol–H2O2 ECL system. The dual enhancement of the ECL signal improved the sensitivity of the sensor. [ABSTRACT FROM AUTHOR]

Schematic diagram of GQDs/C-dots system for imidacloprid detection by FRET. [Display omitted] • A fluorescence resonance energy transfer system base on GQDs/C-dots was developed. • A fluorescence method to detect traces of imidacloprid was designed base on fluorescence quenching. • The fluorescence probe exhibited high sensitivity, and selectivity for imidacloprid. Herein, a fluorescent probe was investigated for the detection of imidacloprid based on the fluorescence resonance energy transfer (FRET) between two carbon-based quantum dots, namely graphene- and carbon quantum dots (GQDs/C-dots). In an HAc-NaAc buffer solution at pH = 5.0, an effective FRET occurred between the GQDs and C-dots, significantly enhancing the C-dot fluorescence. When imidacloprid was added to the FRET system, the fluorescence intensity of the C-dots was quenched in a linear imidacloprid concentration-dependent manner, which allowed for the establishment of a new method for the determination of imidacloprid by GQD/C-dot FRET. Under optimised experimental conditions, the linear range of imidacloprid was 5–4000 × 10−9 mol L−1, with a correlation coefficient r and a detection limit of 0.998 and 8.23 × 10−10 mol L−1, respectively. This method was applied to the detection of imidacloprid residues in real samples, and a satisfactory recovery rate of standard additions was found between 93.0% and 105.6%. [ABSTRACT FROM AUTHOR]

The ketones and benzoic acids are very useful chemicals as the precursors and intermediates in both laboratory and synthetic industrial applications, which are usually obtained by selective catalytic oxidation of alcohols using a amount of certain expensive oxidants or metal catalysts. Here, an efficient and practical oxidation the aryl secondary and primary alcohols to corresponding carbonyl compounds using NaOtBu in open air at room temperature has been developed. And utilizing NaOtBu/air/ toluene, a series of ketones or benzoic acids were obtained from secondary and primary alcohols in high yields, respectively. More importantly, most of the substrates with electron‐withdrawing or electron‐donating groups could be converted to the corresponding products in high to excellent yields. Furthermore, the practicality of the reaction was demonstrated through 1.0 gram‐scale reaction with excellent yield. [ABSTRACT FROM AUTHOR]

Combining electrochemiluminescence (ECL) with nanozyme amplification provides unique advantages for the detection of antibiotic residues. Herein, a molecularly imprinted chloramphenicol (CAP) sensor was established based on aggregation-induced (AI)-ECL and nanozyme amplification. Covalent organic framework materials with AI-ECL groups (COF-AI-ECL) and nanozyme Co 3 O 4 were synthesised as the signal element and the amplification element, respectively. Subsequently, using CAP as a template molecule, a molecularly imprinted polymer (MIP) was fabricated on the electrode surface modified with COF-AI-ECL and Co 3 O 4. The ECL signal of COF-AI-ECL was catalytically amplified by Co 3 O 4 , whereas CAP effectively quenched this signal. Consequently, the ECL signal was controlled by the elution and adsorption of CAP by the MIP, thus establishing a new method for CAP detection. Unlike traditional ECL reagent, COF-AI-ECL exhibited a stable and strong ECL signal. Therefore, COF-AI-ECL in combination with the MIP provided greater sensitivity and enhanced selectivity. The linear range of the developed CAP sensor was 5 × 10−13 to 4 × 10−10 mol/L, with a detection limit of 1.18 × 10−13 mol/L. Moreover, the recoveries range of 85.0%–106.2% were obtained for the detection of CAP in real honey, milk, and chicken samples, indicating the potential of this sensor design for the detection of trace antibiotic residues in food safety applications. • A chloramphenicol sensor base on COF-AI-ECL materials was developed. • The ECL reagent provided a stable signal that was amplified by nanozyme Co 3 O 4. • A molecularly imprinted polymer enhanced the selectivity for chloramphenicol. • The sensor exhibited high sensitivity, stability, and reproducibility. [ABSTRACT FROM AUTHOR]

Fluorescence intensity and selective recognition ability are crucial factors in determining the analytical techniques for fluorescent probes. In this study, a core–shell fluorescent material, composed of silver nanoparticles@nitrogen-doped graphene quantum dots (Ag NPs@N/GQDs), was synthesised using mango leaves as the raw material through a thermal cracking method, resulting in strong fluorescence luminescence intensity. By employing noradrenaline as a template molecule and using a surface molecular imprinting technique, a molecularly imprinted membrane (MIP) was formed on the surface of the fluorescent material, that was subsequently eluted to obtain a highly specific, fluorescent probe capable of recognising noradrenaline. The probe captured various concentrations of noradrenaline using the MIP, which decreased the fluorescence intensity. Then a method for detecting trace amounts of noradrenaline was established. This method exhibited a linear range from 0.5 –700 pM with a detection limit of 0.154 pM. The proposed method was implemented in banana samples. Satisfactory recoveries were confirmed at four different concentrations. The method presented a relative standard deviation (RSD) of less than 5.0%. [ABSTRACT FROM AUTHOR]

A highly selective and amplification strategy levamisole sensor using an electrode modified with a Cu/Zn-trimesic-acid MOF and an molecularly imprinted polymer. Cu/Zn-BTC fixed the conformation of levamisole in the first step of the recognition, whereas the MIP formed weak hydrogen bonds with levamisole in the second stage in the sensor. The combination of these two recognition processes effectively improved the levamisole-recognising ability of the sensor. Additionally, the bimetallic MOF material doubly amplified the probe signal, effectively improving the detection sensitivity. The sensor showed excellent chiral recognition attributes and high sensitivity for levamisole. [Display omitted] • An electrochemical sensor was built to distinctly detect the trace levamisole enantiomer. • A molecularly imprinted polymer and Cu-Zn/BTC were used for improving selectivity of sensor. • Cu-Zn/BTC can effectively amplify the current response signal of the sensor. • The sensor showed excellent selectivity for levamisole and excluded dextramisole interference. We used an enhanced recognition strategy to fabricate a novel levamisole-detecting chiral electrochemical sensor featuring a metal–organic framework (MOF) combined with a molecularly imprinted polymer (MIP). We first synthesised a Cu/Zn-[benzene-1,3,5-tricarboxylic acid] (Cu/Zn-BTC) MOF as the molecular immobilisation and signal-amplifying unit, and then prepared the MIP (molecular recognition unit) using levamisole as the template on a glassy carbon electrode modified with Cu/Zn-BTC. We obtained a composite chiral sensor with enhanced recognition capability for levamisole after template removal. Using the templated sites as the switch and K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] as a probe, we established a new method for detecting levamisole in meat products and water bodies. The linear detection range and detection limit of our chiral sensor are 5 to 6000 × 10-11 mol/L and 1.65 × 10−12 mol/L, respectively. Moreover, the sensor exhibited 93.8–109.0% recovery in the detection of levamisole in chicken and other real samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • The polycentric affinity of PCN-224(Zn) on organophosphorus was confirmed. • Nb 4 C 3 was introduced into MOF-based heterojunction to enhance PEC properties. • Polycentric affinity cooperative MIPs achieves precise capture of targets. • The proposed sensor detects dimethoate at pM level in water & fruits. The analytical functionalization of metal organic frameworks (MOFs) has been an extremely attractive topic in photoelectrochemical (PEC) sensing. However, most PEC sensors based on photoactive MOFs are more focused on the acquisition and amplification of semiconductor photoelectric signals, and the study of affinity mechanisms for specific targets is more limited. Here, we find that PCN-224 (Zn) can effectively sense organophosphorus structures through a multicenter affinity mechanism, as evidenced by x-ray photoelectron spectroscopy (XPS) and computational chemistry. Further, we coupled PCN-224(Zn) to Nb 4 C 3 to form a Schottky junction that enhances the photoelectric signal response of the sensor. In particular, the heterojunction exhibited a higher photocurrent density than pristine PCN-224(Zn) (17.3 μA vs. 26.5 μA cm−2). On the basis, we developed a novel MOF-based polycentric-affinity PEC sensing strategy for dimethoate (DIM) detection in concert with molecular imprinting technology. The affinity effects of the Lewis acidic center sites (Zn(II), Zr(IV)) and spatial matching through molecular imprinting synergistically ensure that DIM is precisely captured. Ultimately, a trace DIM-PEC sensor was constructed by a competitive strategy using dopamine as an electron donor. The photocurrent intensity was linearly related to the logarithm of DIM concentration in the range of 0.1 nM to 1000 nM, with a low detection limit of 26.1 pM (3σ/S). This study demonstrates the potential of bifunctional polycentric-affinity MOF in the PEC sensing. [ABSTRACT FROM AUTHOR]

The authors describe a method of electrochemiluminescent quantitation of the antibiotic sulfaquinoxaline (SQX). It relies on the use of a molecularly imprinted polymer and a Cu(II)-anchored unzipped covalent triazine framework (UnZ-CCTF) with excellent dispersibility, electrical conductivity, and peroxidaze-like activity. The framework was prepared by unzipping a covalent triazine framework under retention of basic triazine units. It was morphologically and structurally characterized by a range of instrumental techniques. The excellent peroxidase-mimicking effect of UnZ-CCTF on the electrochemiluminescence of the luminol/H2O2 system was exploited to design an ultrasensitive SQX assay with a 1.0-20 pM detection range and a detection limit of 0.76 pM (at 3δ/m). The technique was used for SQX quantitation in spiked milk samples, achieving recoveries of 94.0-104.8%.Scheme of the sulfaquinoxaline molecularly imprinted electrochemiluminescence sensor based on Cu-anchored unzipped covalent triazine frameworks. [ABSTRACT FROM AUTHOR]

An electrochemiluminescence (ECL) switch sensor with a dual-recognition mechanism was developed based on complexation reactions and a molecular imprinted film (MIP). The MIP was prepared on a gold electrode with ferroferric oxide/carbon quantum dots (Fe 3 O 4 /C-dots) via electrochemical polymerization. An L -canavanine–trinitrobenzene complex was used as the template molecule and o -phenylenediamine was used as the functional monomer. Further, C-dots were used as the ECL signal elements and the L -canavanine–trinitrobenzene complex could quench the ECL signal. Subsequently, by using the elution and re-adsorption of the template molecule as the control switch, it was possible to control the ECL intensity of the sensor, and establish a new method for rapidly measuring L -canavanine. A sensor that combined complexation recognition and imprinting recognition demonstrated excellent performance in terms of recognizing specific target molecules. The detection limits of this method reached 7.32 × 10−11 mol L−1, and the measurement results for practical samples were satisfactory. • A novel molecularly imprinted molecular switch sensor is fabricated for biotoxin L -canavanine determination. • The dual-recognition system between molecular imprinting polymers and trinitrobenzene is the first studied. • Fe 3 O 4 /C-dots act as electrochemiluminescence element, and establish a new method for measuring L -canavanine sensitively. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO/Au NPs/β-CD modified electrode base-electrochemical sensor for imidacloprid determination reported for the first time. • Multiple amplification strategy enhanced sensitivity. • Excellent range of response, limit of detection, repeatability, and selectivity. The key to improving the sensitivity of electrochemical sensors for direct detection is the introduction of catalytically amplified nanomaterials. Accordingly, in this study, a new strategy for the preparation of electrochemical sensors with multiple amplification effects is proposed. Graphene oxide (GO), gold nanoparticles (Au NPs), and β-cyclodextrin (β-CD) were introduced to the surface of a glassy carbon electrode via cyclic voltammetry to prepare a modified electrode sensor with a GO/Au NPs/β-CD thin film. The prepared sensor effectively catalyzed and amplified the reduction current of imidacloprid in a B-R buffer with pH = 5.0 owning to the multiple amplification effects of GO/Au NPs/β-CD. A good linear relationship was observed the level of the reduction current response and the imidacloprid at concentrations ranging from approximately 5 × 10−10 to 3000 × 10−10 mol/L; thus, a new imidacloprid detection method using an electrochemical sensor was established. The new method, whose detection limit reached 1.33 × 10−10 mol/L, was tested on actual samples, achieving recoveries of 92.0 % to 110.0 %. [ABSTRACT FROM AUTHOR]

Owing to its unique features including low background noise, high signal-to-noise ratio, and rapid response, photoelectrochemical (PEC) sensing is a state-of-the-art platform for rapidly and accurately monitoring target compounds. Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) are key porous crystalline materials that show exceptional potential for application in PEC sensors. A timely and systematic review of the recent progress made and future research trends is valuable for accelerating MOF/COF-based PEC sensor development. This review first discusses the photoactive MOF/COF design principles and key PEC performance control factors by elucidating typical strategies for designing and fabricating photoactive MOFs/COFs to improve photoexcitation, charge separation/transfer. Then, an overview of the considerable progress made in applying MOF/COF-based materials to PEC sensing is presented including pristine MOFs/COFs, MOF/COF-based heterojunctions, MOF derivatives, and MOF/COF hybrids. Finally, the critical challenges for practical applications of MOF/COF-based PEC sensors and the research prospects are briefly discussed. • Recent advances reviewed for M/COF materials for PEC sensor applications. • Overview provides essential M/COF background information. • Key photoactive M/COF controlling factors are discussed. • Application of M/COF-based materials to PEC sensors is explored. • Research prospects proposed for developing commercial M/COF PEC sensor applications. [ABSTRACT FROM AUTHOR]

A dual selection/recognition effect is described for cobalt (II) ions (Co2+). It is based on bovine serum albumin-metal-Co2+ coordination (BSA-Co2+) and the use of a molecularly imprinted polymer (MIP). An electrochemiluminescence (ECL) switch sensor was designed for detecting nanomolar levels of Co2+. The BSA-Co2+ coordination complex was chosen as a template to prepare a MIP modified switch sensor. The coordination reaction between BSA and Co2+ provides the first step in recognition, and MIP provides the second step for Co2+. This leads to a strong improvement in selectivity of the sensor. A multi-walled carbon nanotube/Cu nanoparticles/carbon quantum dots nanocomposite (MWCNT/Cu/C-dots) acts as an ECL device, and the BSA-Co2+ complex quenches the ECL signal. Therefore, the elution and resorption of BSA-Co2+ can be used as a switch to control ECL. Additionally, a method was established to detect Co2+, with the detection limit as low as 3.07 × 10−10 mol/L. The method was applied to the analysis of spiked environmental water, soil samples, and agricultural products. The recovery rates of the method were in the range of 87.5–111.3%. • A novel switch sensor base on MIP and BSA-Co2+ coordination as recognition elements is fabricated for Co2+ determination. • MWCNT/Cu/C-dots are act as electrochemiluminescence element for measuring Co2+ sensitively. [ABSTRACT FROM AUTHOR]