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This work demonstrates rapid sensing of kaempferol using active sensing material synthesized using the one-pot surface-imprinting synthesis method. This sensor consisted of molecularly imprinted polymer (MIP) consisting of mesoporous molecular sieves (SBA-15) loaded with carbon dots (CDs). Fourier transform infrared (FT-IR) spectroscopy confirmed successful incorporation of CDs onto the surface of imprinted mesoporous molecular sieves. Ordered hexagonal arrays of CDs@SBA-15@MIP mesopore structure were confirmed with transmission electron microscopy. Fluorescence intensity of CDs@SBA-15@MIP composites linearly correlated with kaempferol content in the 0.05–2 mg/L range. Detection limit was 14 μg/L. MIPs were used for efficient detection of kaempferol in fruit and vegetable samples with recovery values from 80% to 112%. The method has high sensitivity, low cost, good selectivity, and many application potentials useful for research and development of flavonoid monomer presence in food. [ABSTRACT FROM AUTHOR]

A highly efficient and selective method based on core–shell molecularly imprinted polymers (MIL@MIP) and high performance liquid chromatography (HPLC) was developed and firstly used for the trace analysis of tribenuron-methyl (TBM) in complicated matrices. The MIL@MIP was prepared by surface molecular-imprinting technique, specially using MIL-101 as core, TBM as template molecule, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and azobisisobutyronitrile (AIBN) as initiator. The resulting MIL@MIP showed high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance towards TBM with the adsorption capacity reaching up to 3.217 mg/g. It also showed high cross-selectivity for TBM among its six kinds of chemical structure analogues. Furthermore, using the MIL@MIP as solid-phase extraction (SPE) materials, the recoveries of TBM determined by HPLC were 84.6-92.3%, 93.3-106.7%, and 88.9-93.3% in the spiked river water, soil, and soybean samples, respectively, with the limit of detection of 0.3 ng/L, 1.5 ng/kg, and 1.5 ng/kg, accordingly. It was proved that the developed HPLC-MISPE method was fast, accurate, and sensitive for detecting the trace TBM in river water, soil, and soybean samples. [ABSTRACT FROM AUTHOR]

A novel molecular imprinting fluorescent sensor synthesized avoiding complicated design and synthesis of a fluorescent functional monomer, and without the extra cost of additional fluorescence materials (quantum dots, carbon dots and fluorescein), only by a click reaction making the common protein imprinting polymers upgraded to a fluorescent sensing material which can be applied to the fast detection of glycoproteins. In this study, a common protein imprinted polymer (protein-IP) which containing a disulfide bond in the imprinted cavities was first synthesized, then the disulfide linkage was cleaved by reduction, the exposed thiol groups were used for the click reaction to introduce 4-vinyl phenylboronic acid to improve the imprinted recognition for glycoproteins and convert recognition behavior into fluorescent signal simultaneously in one-step site-specific post-imprinting modifications (PIMs). Good linear relationship was obtained in the range of 0.1–10 mg mL −1 by fluorescence assay, comparison of the adsorption capacity of the MIPs before and after modification proved that the method has no negative impact on the imprinting effect and exhibit good imprinting effect for glycoproteins of different molecular size and weight. [ABSTRACT FROM AUTHOR]

Abstract: A novel molecularly imprinted polymer that could be applied as enrichment sorbent was prepared using methimazole (MMZ) as the template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker. Though evaluated by static, kinetic and competitive adsorption tests, the polymer exhibited high adsorption capacity, fast kinetics and good selective ability. A method for determination of trace MMZ was developed using this polymer as enrichment sorbent coupled with high performance liquid chromatography focusing on complex biological matrices. Under the optimum experimental conditions, the MMZ standard is linear within the concentration range studied, that is, from 0.5μgL−1 to 150μgL−1 (r 2 =0.9941). Lower limits of detection (LOD, at S/N=3) and quantification (LOQ, at S/N=10) in pig samples were 0.63μgkg−1 and 2.10μgkg−1 for kidney, 0.51μgkg−1 and 1.70μgkg−1 for liver, 0.56μgkg−1 and 1.86μgkg−1 for muscle, respectively. Recoveries and relative standard deviation (RSD, n =9) values for precision in the developed method were from 71.14% to 88.41% and from 2.53% to 6.18%. [Copyright &y& Elsevier]

In this work, a novel molecularly imprinted polymer (MIP) with water-soluble CdTe quantum dots (QDs) was synthesized by oil-in-water Pickering emulsion polymerization using whole Listeria monocytogenes as the template. Listeria monocytogenes was first treated by acryloyl-functionalized chitosan with QDs to form a bacteria–chitosan network as the water phase. This was then stabilized in an oil-in-water emulsion comprising a cross-linker, monomer, and initiator, causing recognition sites on the surface of microspheres embedded with CdTe QDs. The resulting MIP microspheres enabled selective capture of the target bacteria via recognition cavities. The target bacteria Listeria monocytogenes was detected. Scanning electron microscopy (SEM) characterization showed that the MIPs had a rough spherical shape. There was visual fluorescence detection via quenching in the presence of the target molecule, which offered qualitative detection of Listeria monocytogenes in milk and pork samples. The developed method simplified the analysis process and did not require any sample pretreatment. In addition, the fluorescence sensor provided an effective, fast, and convenient method for Listeria monocytogenes detection in food samples. [ABSTRACT FROM AUTHOR]

Highlights • Hydrophilic sulfonamides molecularly imprinted polymers were prepared. • The quantification method was established for trace level sulfonamides detection. • The whole pretreatment process avoided organic solvents consumption. Abstract A water-compatible molecularly imprinted polymer (MIP) was prepared by combining reversible addition-fragmentation chain transfer (RAFT) with reflux precipitation polymerization (RPP) for solid-phase extraction (SPE) coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) to detect six sulfonamides (SAs) in animal-derived foods and water samples. The SEM images indicated the spherical structure of MIP materials. In water medium, MIPs still performed good specific adsorption for SAs. Under the optimized detection conditions, the proposed method offered good linearity (R2 > 0.996) for the six SAs with relative standard deviation (RSD) for ten replicate extractions of 1.64%–4.68%, limits of detection (S/N = 3) of 0.02 μg L−1-0.1 μg L−1 and recoveries of 63.49%–115.72%. Besides, the whole extract process avoided organic solvent consumption, and trace sulfadiazine residues were found in the pork sample at similar concentration of 3.57 and 3.79 μg kg-1 using the MIP-SPE method and commercial Oasis HLB cartridge, respectively. It is confirmed the method could be applied to quantitative detect the trace residue sulfonamides in animal-derived samples and water samples. [ABSTRACT FROM AUTHOR]

• A QCM sensor based on AuNPs doped molecularly imprinted layer and COFs-AuNPs composite was developed. • The sensitive and selective detection was attributed to the employment of COFs-AuNPs and crosslinked imprinting recognition sites. • The COFs-AuNPs composite and three-dimensional structure of imprinted matrix provided more recognition sites for sensing. In this study, for the first time a quartz crystal microbalance (QCM) sensor based on gold nanoparticles (AuNPs) doped molecularly imprinted layer and covalent organic frameworks composite (COFs-AuNPs) was developed for the detection of aflatoxin B1. The AuNPs doped molecularly imprinted layer involved in the crosslinking of o- aminothiophenol functionalized AuNPs (o- ATP@AuNPs) in the present of the templates on electrode surface. The imprinting recognition sites obtained by eluting the templates from imprinted polymer of poly(o- ATP) with AuNPs formed the specific three-dimensional imprinted contours toward the targets. A kind of porous lightweight material–CTpBD COFs and AuNPs were employed jointly to yield the COFs-AuNPs composite which provided large surface area for o- ATP@AuNPs crosslinking. The introduction of COFs-AuNPs substrate and three-dimensional structure of imprinted matrix endowed the sensor with more recognition sites. The sensitive and selective detection was attributed to the loading capacity of the COFs-AuNPs composite and the specific recognition effect of molecularly imprinted polymer of poly(o- ATP) with AuNPs. Under optimal conditions, the proposed sensor showed a wide linear range from 0.05 to 75 ng mL−1, low limit of detection (LOD = 2.8 pg mL−1) and the acceptable recoveries (87.0%−101.7%) in real samples analysis. [ABSTRACT FROM AUTHOR]

Localized photo-polymerization was ingeniously applied to prepare a multifunctional molecularly imprinted polymer (MIP) fluorescent probe using the “layer-by-layer” assembly of MIP and Fe 3 O 4 nanoparticles on NaYF 4 : Yb 3+ , Er 3+ upconversion particles (MUCPs@MIP). Enrofloxacin was used as the template and chosen as the target molecular during the investigation of the adsorption property. This ternary probe has magnetic and broad-spectrum molecular recognition capability, fast response, and upconversion fluorescence. The results of the fluorescence quenching analysis showed good linear ranges of 1.03 nmol/L to 0.28 μmol/L for enrofloxacin, 1.69 nmol/L to 0.22 μmol/L for fleroxacin, 6.92 nmol/L to 0.28 μmol/L for levofloxacin, 7.54 nmol/L to 0.30 μmol/L for ciprofloxacin, and 3.90 nmol/L to 0.25 μmol/L for enoxacin. This probe was further used to determine five quinolones in fish tissues and the recoveries ranging from 90.33% to 108.43% were obtained with relative standard deviation below 5.53%. This work offers a new and general strategy to synthesize a MUCPs@MIP upconversion fluorescence probe with magnetic and selective molecular recognition capability for rapid and accurate sensing of multiple chemical residues in the environment and agri-food products. [ABSTRACT FROM AUTHOR]

• The hollow MIPs for methimazole were prepared by surface imprinted techniques. • A simple H-MIPs sensor was developed for trace methimazole detection. • The sensor was well sensitivity, accuracy, and can simplify the analysis process. • Good recoveries of 88.32%–107.96% were obtained in spiked food samples. In this study, a novel detection method of methimazole was proposed based on the hollow molecularly imprinted quartz crystal microbalance (QCM) sensor, in which the hollow imprinted polymers (H-MIPs) were firstly prepared through the surface imprinted techniques, using hollow silica spheres as matrix supporting material and methimazole as template molecule. The characterizations of H-MIPs were carefully studied. Compared with traditional MIPs, H-MIPs exhibited faster mass transfer rate and higher adsorption capacity. After coating onto the surface of Au chip, the H-MIPs QCM sensor was fabricated. Based on the frequency shift, good linear behavior in the range of 5–70 μg L–1, limit of detection of 3 μg L–1, and good recoveries of 88.32%–107.96% in the spiked pork, beef and milk were obtained. The analysis process could complete within 8 min. The developed sensor provided an effective, fast and accurate method for the methimazole detection in food samples. [ABSTRACT FROM AUTHOR]

• An universal fluorescent encoding strategy was presented. • The encoding process was compatible for different polarity of quantum dots. • Five single-color and 10 dual-color fluorescent systems were obtained. • The fluorescent MIPs performed excellent specific adsorption for dopamine in PBS. • Dual mode fluorescent sensors were successful applied for dopamine detection. As the promising analytical strategy, multi-mode quantum dots (QDs) encoded molecularly imprinted fluorescent sensors have attracted considerable attention. Here, a novel encoding strategy for water-dispersed QDs molecularly imprinted polymers microspheres (MIPMs) with a high-performance fluorescence intensity and multi-color signal was established. The water-compatible MIPMs were firstly synthesized via integrating the reversible addition-fragmentation chain transfer and precipitation polymerization (RAFT-PP), which could improve the water compatibility by grafting the hydrophilic groups of poly(2-hydroxyrthyl methacrylate) (PHEMA). Then the water-compatible MIPMs were used as embedding matrix to separately incorporate with five different QDs, and a series of multi-color QDs encoded MIPs (five single-color and 10 dual-color fluorescent systems) were obtained. The fluorescent characterization of encoded MIPMs was studied in detail. Further, dual-mode fluorescence systems were fabricated as fluorescence sensors for the quantitative detection of dopamine; good linear response in the range of 5-300 μg L-1 and 1-100 μg L-1 and the limit of detection (LOD) with 2 μg L-1 and 0.5 μg L-1 were obtained for monochromatic and ratiometric sensor, respectively. It is the first time to introduce the optical encoding strategy into the fabrication of fluorescent MIPs, which not only greatly simplifies the preparation process of fluorescent imprinted sensor, but also provides more alternatives for the detection method of analyte and the potential of high-throughput multiple analytes at one time. [ABSTRACT FROM AUTHOR]