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[Display omitted] • A unique self-powered MIP–PEC sensor was prepared for BPA detection. • This is the first application of HOFs in constructing MIP–PEC sensors. • The Ppy/QD/HOF heterojunction exhibited excellent photogenerated carrier separation efficiency. • The Ppy-based MIP film has a dual effect of providing selectivity and enhancing photocurrent. • This sensor exhibited good sensitivity, selectivity and applicability. As an emerging porous material, hydrogen-bonded organic framework materials (HOFs) still pose application challenges. In this work, the designed type "I + II" heterojunction extracted hot electrons from HOFs using quantum dots (QDs) and polypyrrole (Ppy), improving the stability and photoelectrochemical performance of materials. In addition to serving as a potential well, electropolymerized Ppy was used as a recognition element for bisphenol A (BPA), and a novel self-powered molecularly imprinted photoelectrochemical (MIP–PEC) sensor was designed. The sensing platform showed a linear relationship from 1 × 10−10 to 1 × 10−7 mol∙L−1 and from 1 × 10−7 to 1 mol∙L−1 with an acceptable detection limit of 4.2 × 10−11 mol∙L−1. This is the first application of HOFs in constructing MIP–PEC sensors and a new attempt to improve the stability of HOFs for the application of porous crystal materials in the sensing field. [ABSTRACT FROM AUTHOR]

[Display omitted] • A portable and on-site MMIECS was fabricated for the rapid detection of TC. • Fe 3 O 4 @COFs@MIPs was used as the sensing platform. • The Fe 3 O 4 @COFs@MIPs was coupled with disposable screen-printed electrode. • The MMIECS exhibited wide linear range, good sensitivity, selectivity, and applicability. • This is the first attempt of applying Fe 3 O 4 @COFs@MIPs in electrochemical sensing. In this study, for the first time, surface molecularly imprinted magnetic covalent organic frameworks (Fe 3 O 4 @COFs@MIPs) were combined with disposable screen-printed electrode (SPE) to construct a portable and on-site electrochemical sensor for the rapid detection of tetracycline (TC). The Fe 3 O 4 @COFs@MIPs, which was prepared by layer-by-layer modification method, had good magnetism and excellent adsorption ability. With the help of disposable SPE, equipped with a magnet, the electrode modification process was simplified and the detection efficiency was improved. Under optimal conditions, the fabricated electrochemical sensor exhibited linearity ranging from 1 × 10−10 to 1 × 10−4 g mL−1. It had good selectivity, excellent reproducibility, desirable stability and remarkable applicability. The fabricated sensor was successfully applied to detect TC in real samples with satisfactory recoveries (96.15–106.20%). The detection strategy separated the recognition and adsorption process from the electrochemical detection process, providing a design idea for the application of COFs in the construction of high-efficiency molecularly imprinted electrochemical sensors. [ABSTRACT FROM AUTHOR]

Quinoxaline-2-carboxylic acid (QCA) is difficult to measure since only trace levels are present in commercial meat products. In this study, a rapid, sensitive and selective molecularly imprinted electrochemical sensor for QCA determination was successfully constructed by combination of a novel modified glassy carbon electrode (GCE) and differential pulse voltammetry (DPV). The GCE was fabricated via stepwise modification of multi-walled carbon nanotubes (MWNTs)-chitosan (CS) functional composite and a sol–gel molecularly imprinted polymer (MIP) film on the surface. MWNTs-CS composite was used to enhance the electron transfer rate and expand electrode surface area, and consequently amplify QCA reduction electrochemical response. The imprinted mechanism and experimental parameters affecting the performance of MIP film were discussed in detail. The resulting MIP/sol–gel/MWNTs-CS/GCE was characterized using various electrochemical methods involving cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and DPV. The sensor using MIP/sol–gel/MWNTs-CS/GCE as working electrode showed a linear current response to the target QCA concentration in the wide range from 2.0×10−6 to 1.0×10−3 molL−1 with a low detection limit of 4.4×10−7 molL−1 (S/N=3). The established sensor with excellent reproductivity and stability was applied to evaluate commercial pork products. At five concentration levels, the recoveries and standard deviations were calculated as 93.5–98.6% and 1.7–3.3%, respectively, suggesting the proposed sensor is promising for the accurate quantification of QCA at trace levels in meat samples. [ABSTRACT FROM AUTHOR]

An advanced molecularly imprinted electrochemical sensor (MIECS) based on two-dimensional materials MXene was developed for determination of triclosan (TCS) in food samples for the first time. Two-dimensional titanium carbide (Ti 3 C 2 T x) were introduced to improve electrochemical response of the MIECS. K+ ions were spontaneously inserted into Ti 3 C 2 T x nanosheets to form K+-Ti 3 C 2 T x by soaking in alkali solution, thus improving the sensitivity of the sensor. Molecularly imprinted polymers (MIP) were prepared by electropolymerization of para aminobenzoic acid (p -ABA), which can specifically recognize TCS. Under optimal conditions, the linear relationship between the current intensity and TCS concentration was obtained from 10 nmol L−1 to 50 μmol L−1 with a low detection limit of 1.18 nmol L−1. The proposed MIECS showed good repeatability for detecting TCS at a concentration of 500 nmol L−1 solution by preparing five parallel modified electrodes, with a relative standard deviation (RSD) of 3.42%. At the spiked concentration levels of 0.05, 0.1, 0.5 mg L−1/mg kg−1, the recoveries range of TCS in peach juice, onions and fish samples were 86.38%–95.52%. The proposed MIECS combining the advantages of Ti 3 C 2 T x and MIP exhibited good sensitivity and selectivity, providing strategy of utilizing MXenes in the construction of electrochemical sensing platform and holding great promise in the field of food safety. [Display omitted] • A novel MIECS was constructed for the determination of trace TCS. • K+ ions were inserted between Ti 3 C 2 T x layers to enhance the MIECS signal. • MIP based on electropolymerized para aminobenzoic acid ensured specific TCS detection. • The MIECS displayed high sensitivity, excellent selectivity and reproducibility. • The MIECS was successfully applied for the detection of TCS in food samples. [ABSTRACT FROM AUTHOR]

• An MMIECS was fabricated for high throughput sensing of OTC. • mMOFs@MIPs was used as the sensing platform. • The mMOFs@MIPs was coupled with magneto electrodes. • This is a first attempt of applying MOFs in the field of MMIECS. • The MMIECS exhibited good sensitivity, selectivity, and applicability. In order to solve inherent problems of traditional molecularly imprinted electrochemical sensors (MIECS), a novel platform of surface molecularly imprinted magnetic metal-organic frameworks (mMOFs@MIPs) was coupled with magneto electrode to establish magnetic MIECS for the recognition of oxytetracycline (OTC). mMOFs@MIPs were synthesized using layer-by-layer modification method for the recognition of OTC. With the help of magneto electrodes, mMOFs@MIPs can be magnetically modified on the electrode surface, forming the electrochemical sensing interface. The imprinted cavities of mMOFs@MIPs can act as the electron channel of the probe to realize label-free detection of OTC. A linear response was obtained within the OTC concentration range of 1.0 × 10−9 g mL−1-1.0 × 10−4 g mL−1. The applicability of the sensor was estimated using the spiking and recovery method in milk samples with the recoveries ranging from 89.0% to 103.1%. It has potential applications in food safety analysis with high throughput detection capability, high specificity and good stability. [ABSTRACT FROM AUTHOR]

A simple quartz crystal microbalance (QCM) sensor based on a sol-gel molecularly imprinted polymer (MIP) film as the recognition element was developed for patulin (PAT) detection. The high adsorption capacity of the proposed MIP for PAT was demonstrated by Scatchard equation analysis. Through the evaluation, based on the QCM frequency change, the developed sensor exhibited a linear concentration range of PAT from 7.5 × 10 −3 μg mL −1 to 6 × 10 −2 μg mL −1 with a lower detection limit of 3.1 × 10 −3 μg mL −1 (S/N = 3). The sensor showed good selective affinity for PAT (selectivity coefficient = 3.82) as well as good reproducibility and long-term stability. The developed sensor was tested on its ability to detect PAT in real samples through a spiking and recovery study with the recoveries ranging from 76.9% to 91.3% (RSDs < 8.4%). The good agreement results of the established MIP-QCM sensor and HPLC–MS method indicated that the developed method could accurately detect PAT in practical food samples. [ABSTRACT FROM AUTHOR]

Nonspecific adsorption of biomolecules (notably, proteins) and bacteria from unsterilized food may occur on sensor surfaces, which is still a challenge for food safety sensing. To achieve sensitive detection of unsterilized raw-food materials, in this study, a U-shaped four-in-one peptide with the sequence Ac-FLKLLKKLL-DOPA 3 -PPPPEEKDQDKEKaa that exhibited anchoring, antifouling, antibacterial, and recognition properties was designed. The peptide-modified sensor surface effectively prevented bacterial adhesion and proliferation while resisting biomolecule adsorption (signal inhibition rate as low as 0.51 % in single-protein solutions). A highly conductive polymer layer of poly(3,4-ethylenedioxythiophene) was introduced to improve the electrochemical performance before U-shaped four-in-one peptide anchoring. The proposed sensor could accurately detect vancomycin, with a wide linear range and limit of detection of 0.05–10 μg mL−1 and 2.06 ng mL−1 (S/N = 3), respectively. Satisfactory recovery rates (101.3–105.3 %) were achieved using diluted fresh goat milk. • A U-shaped four-in-one peptide (Ac-FLKLLKKLL-DOPA 3 -PPPPEEKDQDKEKaa) was designed. • The four-in-one peptide simplifies the construction of the sensor. • The proposed sensor can effectively detect Van residues in diluted fresh goat milk. [ABSTRACT FROM AUTHOR]

A novel molecularly imprinted electrochemical sensor was successfully fabricated for detection of amantadine (AM) residue in animal-derived foods. This molecularly imprinted film was prepared by electrodepositing o -aminothiophenol ( o -AT) on a gold electrode surface by cyclic voltammetry (CV). A series of parameters, including template/monomer ratio, CV scanning cycle number, and immersion time, were optimized in detail for controlling the performance of this imprinted sensor. The fabricated sensor exhibited remarkable characteristics of high selectivity, sensitivity, and reproducibility, and long-term stability for AM detection. The imprinting factor for AM achieved to 2.33 and the selectivity factor for three structural analogues achieved to 6.20, 5.29 and 3.95. Under optimal experimental conditions, good linearity was observed between the current response and AM concentration, ranging from 4.0 × 10 −7 mmol L −1 to 8.0 × 10 −6 mmol L −1 , with a detection limit of 3.06 × 10 −9 mmol L −1 ( S / N = 3). Satisfactory results for the measurement of real samples were also obtained using the proposed sensor, and were consistent with those derived from typical high-performance liquid chromatography-tandem mass spectrometry with a high correlation coefficient (R 2 > 0.99). These results demonstrate that the proposed sensor could serve as a valuable tool for accurate and reliable detection of AM residue in animal-derived foods. [ABSTRACT FROM AUTHOR]