Recent progress in molecularly imprinted media by new preparation concepts and methodological approaches for selective separation of targeting compounds

Sensors Based on Molecularly Imprinted Polymers in the Field of Cancer Biomarker Detection: A Review

Biomarkers play a pivotal role in the screening, diagnosis, prevention, and post-treatment follow-up of various malignant tumors. In certain instances, identifying these markers necessitates prior treatment due to the complex nature of the tumor microenvironment. Consequently, advancing techniques that exhibit selectivity, specificity, and enable streamlined analysis hold significant importance. Molecularly imprinted polymers (MIPs) are considered synthetic antibodies because they possess the property of molecular recognition with high selectivity and sensitivity. In recent years, there has been a notable surge in the investigation of these materials, primarily driven by their remarkable adaptability in terms of tailoring them for specific target molecules and integrating them into diverse analytical technologies. This review presents a comprehensive analysis of molecular imprinting techniques, highlighting their application in developing sensors and analytical methods for cancer detection, diagnosis, and monitoring. Therefore, MIPs offer great potential in oncology and show promise for improving the accuracy of cancer screening and diagnosis procedures.

Synthesis and characterization of magnetic molecularly imprinted polymers for the rapid and selective determination of clofazimine in blood plasma samples

Clofazimine (CLF) is a riminophenazine derivative and a new therapeutic option with high efficacy for patients with rifampicin-resistant tuberculosis (TB). The blood levels of CLF are low and suboptimal, so therapeutic drug monitoring is required. Prior to this study, there were no molecular imprinting-based solid phase extraction (SPE) sorbents that could be used to determine the blood CLF levels. Hence, we prepared a magnetic molecularly imprinted polymer (MMIPs) to capture CLF. We employed computational selection of a functional monomer and crosslinker and confirmed these selections based on the association constant (K a) and a Job plot. We synthesised MMIPs with two surface modifiers and characterized the polymers. Our computational analysis based on the bond energy revealed that methyl methacrylate (MMA) was the most suitable functional monomer at a CLF-to-MMA molar ratio of 1:4. Based on the bond energy, the most suitable crosslinker was trimethylolpropane trimethacrylate (TRIM) at a CLF-to-TRIM molar ratio of 1:1. We determined the K a of MMA and TRIM in different solvents. Isopropanol produced the highest K a. The Job plot showed that a template-to-MMA-to-TRIM molar ratio of 1:4:20 was optimal to synthesize imprinted polymer in isopropanol. We prepared MMIPs using two different modifiers, namely aminopropyltrimethoxysilane (APTES) and oleic acid (OA), using the ratio determined from the Job plot. Physical characteristic tests carried out using FT-IR, SEM-EDS, PSA, BET and VSM, showed that the synthesis was success with a spherical and uniform agglomeration of particles, also a flat surface with many holes with a particle size of MMIP-APTES and MMIP-OA respectively 0.14 μm and 0.28 μm, showed a surface area for MMIP-APTES is 2874.51 m2/g and MMIP-OA 2913.07 m2/g, exhibiting superparamagnetic properties with a saturation magnetization value of MMIP-APTES 21.1 emu/g-1 and MMIP-OA 49.9 emu/g-1. Adsorption capacity result showed that MMIP-OA fits well with the Langmuir model, while MMIP-APTES fits better with the Freundlich. Application of MMIP-SPE (Magnetic Molecular Imprinted Polymer-Solid Phase Extraction) APTES resulted 92.3 ± 6.1 % and MMIP-SPE-OA 51.5 ± 8.1 % for recovering CLF in blood. The result of selectivity test also showed that MMIP-SPE-APTES is better than MMIP-SPE-OA and selectively recover CLF from human blood plasma existed together with other TB-Drugs. The study result shows that MMIPs with APTES modification can be used for CLF determination in human blood plasma.

Mycotoxins-Imprinted Polymers: A State-of-the-Art Review

Mycotoxins are toxic metabolites of molds which can contaminate food and beverages. Because of their acute and chronic toxicity, they can have harmful effects when ingested or inhaled, posing severe risks to human health. Contemporary analytical methods have the sensitivity required for contamination detection and quantification, but the direct application of these methods on real samples is not straightforward because of matrix complexity, and clean-up and preconcentration steps are needed, more and more requiring the application of highly selective solid-phase extraction materials. Molecularly imprinted polymers (MIPs) are artificial receptors mimicking the natural antibodies that are increasingly being used as a solid phase in extraction methods where selectivity towards target analytes is mandatory. In this review, the state-of-the-art about molecularly imprinted polymers as solid-phase extraction materials in mycotoxin contamination analysis will be discussed, with particular attention paid to the use of mimic molecules in the synthesis of mycotoxin-imprinted materials, to the application of these materials to food real samples, and to the development of advanced extraction methods involving molecular imprinting technology.

Recent molecularly imprinted polymers applications in bioanalysis

Molecular imprinted polymers (MIPs) as extraordinary compounds with unique features have presented a wide range of applications and benefits to researchers. In particular when used as a sorbent in sample preparation methods for the analysis of biological samples and complex matrices. Its application in the extraction of medicinal species has attracted much attention and a growing interest. This review focus on articles and research that deals with the application of MIPs in the analysis of components such as biomarkers, drugs, hormones, blockers and inhibitors, especially in biological matrices. The studies based on MIP applications in bioanalysis and the deployment of MIPs in high-throughput settings and optimization of extraction methods are presented. A review of more than 200 articles and research works clearly shows that the superiority of MIP techniques lies in high accuracy, reproducibility, sensitivity, speed and cost effectiveness which make them suitable for clinical usage. Furthermore, this review present MIP-based extraction techniques and MIP-biosensors which are categorized on their classes based on common properties of target components. Extraction methods, studied sample matrices, target analytes, analytical techniques and their results for each study are described. Investigations indicate satisfactory results using MIP-based bioanalysis. According to the increasing number of studies on method development over the last decade, the use of MIPs in bioanalysis is growing and will further expand the scope of MIP applications for less studied samples and analytes.

Factors Affecting the Analytical Performance of Magnetic Molecularly Imprinted Polymers

During the last few years, separation techniques using molecular imprinting polymers (MIPs) have been developed, making certain improvements using magnetic properties. Compared to MIP, Magnetic molecularly imprinted polymers (MMIPs) have high selectivity in sample pre-treatment and allow for fast and easy isolation of the target analyte. Its magnetic properties and good extraction performance depend on the MMIP synthesis step, which consists of 4 steps, namely magnetite manufacture, magnetic coating using modified components, polymerization and template desorption. This review discusses the factors that will affect the performance of MMIP as a selective sorbent at each stage. MMIP, using Fe₃O₄ as a magnetite core, showed strong superparamagnetism; it was prepared using the co-precipitation method using FeCl₃·6H₂O and FeCl₂·H₂O to obtain high magnetic properties, using NH₄OH solution added for higher crystallinity. In magnetite synthesis, the use of a higher temperature and reaction time will result in a larger nanoparticle size and high magnetization saturation, while a higher pH value will result in a smaller particle size. In the modification step, the use of high amounts of oleic acid results in smaller nanoparticles; furthermore, determining the correct molar ratio between FeCl₃ and the shielding agent will also result in smaller particles. The next factor is that the proper ratio of functional monomer, cross-linker and solvent will improve printing efficiency. Thus, it will produce MMIP with high selectivity in sample pre-treatment.

Chemiluminescence sensors based on molecularly imprinted polymers for the determination of organophosphorus in milk

As a food adapted to all kinds of people, milk has a high nutritional value. Because milk is a complex biological matrix, detecting illegal compounds is often difficult. As a common pesticide, organophosphorus (OP) residues caused by nonstandard use may be ignored, which is a threat to milk quality. In this study, using coumaphos as template molecule, the synthesized molecularly imprinted polymer (MIP) can specifically recognize 7 kinds of OP. Then, the MIP was used as an identification element to prepare a chemiluminescence sensor on a 96-well microplate for the determination of OP residues in milk samples. Due to the 4-(imidazol-1-yl)phenol-enhanced luminol-H₂O₂ system, the sensitivity of the system is very high; the detection limits of 7 OP including coumaphos, fenthion, chlorpyrifos, parathion, diazinon, fenchlorphos, and fenitrothion were 1 to 3 pg/mL, and the half maximal inhibitory concentrations were 1 to 20 ng/mL. The intraday recoveries of 7 OP were in the range of 86.1 to 86.5%, and the interday recoveries were in the range of 83.6 to 94.2%. Furthermore, the sensor can be reused up to 5 times. Therefore, the MIP-based chemiluminescence sensor can be used as a routine tool to detect OP residues in milk samples.

Recent advances and applications of molecularly imprinted polymers in solid-phase extraction for real sample analysis

Sample pretreatment is essential for the analysis of complicated real samples due to their complex matrices and low analyte concentrations. Among all sample pretreatment methods, solid-phase extraction is arguably the most frequently used one. However, the majority of available solid-phase extraction adsorbents suffer from limited selectivity. Molecularly imprinted polymers are a type of tailor-made artificial antibodies and receptors with specific recognition sites for target molecules. Using molecularly imprinted polymers instead of conventional adsorbents can greatly improve the selectivity of solid-phase extraction, and therefore molecularly imprinted polymer-based solid-phase extraction has been widely applied to separation, clean up and/or preconcentration of target analytes in various kinds of real samples. In this article, after a brief introduction, the recent developments and applications of molecularly imprinted polymer-based solid-phase extraction for determination of different analytes in complicated real samples during the 2015-2020 are reviewed systematically, including the solid-phase extraction modes, molecularly imprinted adsorbent types and their preparations, and the practical applications of solid-phase extraction to various real samples (environmental, food, biological, and pharmaceutical samples). Finally, the challenges and opportunities of using molecularly imprinted polymer-based solid-phase extraction for real sample analysis are discussed.

An overview on molecular imprinted polymers combined with surface-enhanced Raman spectroscopy chemical sensors toward analytical applications

Surface-enhanced Raman spectroscopy (SERS) is a powerful and high-speed detection technology. It provides information on molecular fingerprint recognition with ultrahigh sensitive detection. However, it shows poor anti-interference capacity against complex matrices. Molecularly imprinted polymers (MIPs) can achieve specific recognition of targets from complex matrices. Through introducing the MIP separation system, the MIP-SERS chemical sensor can effectively overcome the limitation of complex matrix interference, and further improve the stability of sensors for detection. Herein, the materials and structures of integrated MIP-SERS sensors are systematically reviewed, and its application as a sensor for chemical detection of hazardous substances in environmental and food samples has been addressed as well. To broaden the prospects of application, we have discussed the current challenges and future perspectives that would accelerate the development of versatile MIP-SERS chemical sensors.

Antimicrobial magnetic poly(GMA) microparticles: synthesis, characterization and lysozyme immobilization

Micron-sized magnetic particles currently find a wide range of applications in many areas including biotechnology, biochemistry, colloid sciences and medicine. In this study, magnetic poly(glycidyl methacrylate) microparticles were synthesized by providing a polymerization around Fe(II)-Ni(II) magnetic double salt. Adsorption of lysozyme protein from aqueous systems was studied with these particles. Adsorption studies were performed with changing pH values, variable amount of adsorbent, different interaction times and lysozyme amounts. The adsorption capacity of the particles was investigated, and a value of about 95.6 mg lysozyme/g microparticle was obtained. The enzyme activity of the immobilized lysozyme was examined and found to be more stable and reusable compared to the free enzyme. The immobilized enzyme still showed 80% activity after five runs and managed to maintain 78% of its initial activity at the end of 60 days. Besides, in the antimicrobial analysis study for six different microorganisms, the minimum inhibitory concentration value of lysozyme immobilized particles was calculated as 125 μg/mL like free lysozyme. Finally, the adsorption interaction was found to be compatible with the Langmuir isotherm model. Accordingly, it can be said that magnetic poly(GMA) microparticles are suitable materials for lysozyme immobilization and immobilized lysozyme can be used in biotechnological studies.

Thermo-responsive imprinted hydrogel with switchable sialic acid recognition for selective cancer cell isolation from blood

In this work, a sialic acid (SA)-imprinted thermo-responsive hydrogel layer was prepared for selective capture and release of cancer cells. The SA-imprinting process was performed at 37 °C using thermo-responsive functional monomer, thus generating switchable SA-recognition sites with potent SA binding at 37 °C and weak binding at a lower temperature (e.g., 25 °C). Since SA is often overexpressed at the glycan terminals of cell membrane proteins or lipids, the SA-imprinted hydrogel layer could be used for selective cancer cell recognition. Our results confirmed that the hydrogel layer could efficiently capture cancer cells from not only the culture medium but also the real blood samples. In addition, the captured cells could be non-invasively released by lowing the temperature. Considering the non-invasive processing mode, considerable capture efficiency, good cell selectivity, as well as the more stable and durable SA-imprinted sites compared to natural antibodies or receptors, this thermo-responsive hydrogel layer could be used as a promising and general platform for cell-based cancer diagnosis.

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Thermo-responsive sialic acid (SA)-imprinted hydrogel layer was prepared.

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The hydrogel layer could efficiently and selective capture cancer cells at 37 °C.

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The captured cancer cells could be released at a lower temperature (e.g., 25 °C).

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The hydrogel layer could be used for capture and release cancer cells from blood.

Advancements of chiral molecularly imprinted polymers in separation and sensor fields: A review of the last decade

Since chiral recognition mechanism based on molecularly imprinted polymers immerged, it has assisted countless chemical and electrochemical analytical sample preparation techniques. It has done this by enhancing the enatioseparation abilities of these techniques. The preparation and optimization of chiral molecularly imprinted polymers (CMIPs) are two favored methods in the separation and sensor fields. This review aims to present an overview of advances in the preparation and application of CMIPs in analytical approaches in different available formats (eg. column, monolithic column, cartridge, membrane, nanomaterials, pipette tip and stir bar sorptive) over the last decade. In addition, progress in the preparation and development of CMIPs-based sensor fields have been also discussed. Finally, the main application challenges of CMIPs are also summarily explained, as well as upcoming prospects in the field.

Microsphere Polymers in Molecular Imprinting: Current and Future Perspectives

Molecularly imprinted polymers (MIPs) are specific crosslinked polymers that exhibit binding sites for template molecules. MIPs have been developed in various application areas of biology and chemistry; however, MIPs have some problems, including an irregular material shape. In recent years, studies have been conducted to overcome this drawback, with the synthesis of uniform microsphere MIPs or molecularly imprinted microspheres (MIMs). The polymer microsphere is limited to a minimum size of 5 nm and a molecular weight of 10,000 Da. This review describes the methods used to produce MIMs, such as precipitation polymerisation, controlled/'Living' radical precipitation polymerisation (CRPP), Pickering emulsion polymerisation and suspension polymerisation. In addition, some green chemistry aspects and future perspectives will also be given.

Molecularly imprinted polymer functionalized silica nanoparticles for enantioseparation of racemic tryptophan in aqueous solution

A method has been developed for preparation of surface molecularly imprinted polymer functionalized silica nanoparticles (SiO₂@MPS@MIP). Firstly, the silica nanoparticles are prepared by a one-pot sol-gel method using tetraethylorthosilicate and 3-methacryloxypropyltrimethoxysilane as functional monomers. Next, the template molecule (L-Trp) is self-assembled with the functional monomer (acrylamide). Finally, SiO₂@MPS@MIP are prepared using N,N'-methylenebisacrylamide as the cross-linker. The prepared SiO₂@MPS@MIP have an average diameter of about 6.3 ± 1.2 nm. They exhibit good selectivity toward L-Trp with an imprinting factor of 6.3. The adsorption isotherm data was well described by the Langmuir model. The maximum adsorption capacities of SiO₂@MPS@MIP for L-Trp and D-Trp were calculated to be 11.1 ± 0.9 and 2.66 ± 0.16 mg g^-1, respectively. An enantiomer excess value of 100% was achieved after adsorption of racemic Trp by the material. The work suggests that SiO₂@MPS@MIP are a promising material for enantioseparation of Trp racemate in aqueous media. Graphical abstract.

The preparation and evaluation of core-shell magnetic dummy-template molecularly imprinted polymers for preliminary recognition of the low-mass polybrominated diphenyl ethers from aqueous solutions

The design, preparation process, binding abilities, morphological characteristic and prospective field of application of dummy-template magnetic molecularly imprinted polymer (DMMIP) for preliminary recognition of the selected low-mass polybrominated diphenyl ethers (PBDE-47 and PBDE-99) from aquatic environment were investigated. The surface of iron oxide (Fe₃O₄) nanopowder (50-100 nm particles size) was modified with tetraethoxysilane and next prepared Fe₃O₄@SiO₂ particles were dispersed in anhydrous toluene functionalized by (3-aminopropyl)triethoxysilane. Finally, MIPs' thin film layer on the surface of Fe₃O₄@SiO₂@NH₂ was formed in acetonitrile as a solvent solution, using ethylene glycol dimethacrylate as the cross-linker, building monomer, 1,1'-Azobis(cyclohexanecarbonitrile) as the radical initiator, methacrylic acid as a functional monomer and 4,4'-Dihydroxydiphenyl ether as the dummy template molecule as a structural analogue of low-mass PBDEs. To characterize the chemical structure of prepared DMMIPs, the Fourier transform infrared spectroscopy analysis was performed. The specific surface area of the developed sorbent was estimated using Brauner-Emmet-Teller nitrogen adsorption/desorption analysis. To assess the average pore sizes, pore diameters and pore volumes of the prepared sorbent, the Barret-Joyner-Halenda technique was applied. The average values of imprinting factor for PBDE-47 and PBDE-99 were 11.3 ± 1.6 and 13.7 ± 1.2, respectively. The average value of recovery of PBDE-47 and PBDE-99 for developed DMMIPs from modelling water: methanol solution were 85.4 ± 6.7% and 86.4 ± 9.4%, respectively. In a case of spiked distilled water, tap water as well as local river water the calculated recovery values ranged from 65%% up to 82% and from 33% up to 76% for PBDE-47 and PBDE-99, respectively. Following the preliminary research on selected water samples, the proposed combination of imprinting technology and core-shell materials with magnetic properties might be considered as a promising sorption tool used for targeted recognition of low-mass PBDEs in aquatic solutions.

The role of analytical chemistry in exposure science: Focus on the aquatic environment

Exposure science, in its broadest sense, studies the interactions between stressors (chemical, biological, and physical agents) and receptors (e.g. humans and other living organisms, and non-living items like buildings), together with the associated pathways and processes potentially leading to negative effects on human health and the environment. The aquatic environment may contain thousands of compounds, many of them still unknown, that can pose a risk to ecosystems and human health. Due to the unquestionable importance of the aquatic environment, one of the main challenges in the field of exposure science is the comprehensive characterization and evaluation of complex environmental mixtures beyond the classical/priority contaminants to new emerging contaminants. The role of advanced analytical chemistry to identify and quantify potential chemical risks, that might cause adverse effects to the aquatic environment, is essential. In this paper, we present the strategies and tools that analytical chemistry has nowadays, focused on chromatography hyphenated to (high-resolution) mass spectrometry because of its relevance in this field. Key issues, such as the application of effect direct analysis to reduce the complexity of the sample, the investigation of the huge number of transformation/degradation products that may be present in the aquatic environment, the analysis of urban wastewater as a source of valuable information on our lifestyle and substances we consumed and/or are exposed to, or the monitoring of drinking water, are discussed in this article. The trends and perspectives for the next few years are also highlighted, when it is expected that new developments and tools will allow a better knowledge of chemical composition in the aquatic environment. This will help regulatory authorities to protect water bodies and to advance towards improved regulations that enable practical and efficient abatements for environmental and public health protection.

Determination of sulfonamides in meat with dummy-template molecularly imprinted polymer-based chemiluminescence sensor

In this study, a molecularly imprinted polymer capable of recognizing 15 sulfonamides was first synthesized with sulfabenz as the dummy template. The calculation results from computation simulation showed that the specific 3D conformation of the template had an important influence on the polymer's recognition ability. Then, the polymer was used as recognition reagent to prepare a chemiluminescence sensor on a conventional 96-well microplate for the determination of the residues of 15 sulfonamides in meat (chicken and pork). Due to the 4-(imidazol-1-yl)phenol-enhanced luminol-H₂O₂ system, the limits of detection for the 15 analytes were in the range of 1.0-12 pg/mL. The recoveries from the standard fortified blank samples were in the range of 72.7-99%. Furthermore, one assay could be finished within 30 min, and the sensor could be reused 4 times. Therefore, this sensor could be used as a very useful tool for routine screening of residues of sulfonamides in meat samples. Graphical abstract Assay procedures of the molecularly imprinted polymer-based chemiluminescence sensor for determination of sulfonamides.

Efficient extraction of estrogen receptor-active compounds from environmental surface water via a receptor-mimic adsorbent, a hydrophilic PEG-based molecularly imprinted polymer

We report an efficient screening procedure for the selective detection of compounds that are actively bound to estrogen receptor (ER) from environmental water samples using a receptor-mimic adsorbent prepared by a molecularly imprinted polymer (MIP). To mimic the recognition ability of ER, we improved the typical MIP preparation procedure using a hydrophilic matrix with a polyethylene glycol (PEG)-based crosslinker and a hydrophobic monomer to imitate the hydrophobic pocket of ER. An optimized MIP prepared with methacrylic acid as an additional functional monomer and estriol (E3), an analogue of 17β-estradiol (E2), exhibited highly selective adsorption for ER-active compounds such as E2 and E3, with significant suppression of non-specific hydrophobic adsorption. The prepared MIP was then applied to the screening of ER-active compounds in sewage samples. The fraction concentrated by the MIP was evaluated by in vitro bioassay using the yeast two-hybrid (Y2H) method and liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOFMS). Compared to an authentic adsorbent, styrene-divinylbenzene (SDB)-based resin, the fraction concentrated by the MIP had 120% ER activity in the Y2H assay, and only 25% peak volume was detected in LC-Q-TOFMS. Furthermore, a few ER-active compounds were identified only from the fraction concentrated by the MIP, although they could not be determined in the fraction concentrated by the SDB-based resin due to ion suppression along with high levels of hydrophobic compounds. These results indicated that the newly developed MIP effectively captured ER-active compounds and while allowing most non-ER-active compounds to pass through.

New protocol for optimisation of polymer composition for imprinting of peptides and proteins

A novel screening tool for high-throughput optimisation of monomer composition for imprinting of peptides and proteins.

Molecularly Imprinted Polymer Based Chemiluminescence Method for Detection of Nitrofurans

In this study, a molecularly imprinted polymer capable of simultaneously recognising seven nitrofurans is synthesised. The polymer particles coated the wells of a conventional 96-well microplate as the recognition element. After sample loading, the analytes were absorbed and a highly sensitive imidazole-enhanced bis(2,4,6-trichlorophenyl) oxalate–H2O2 system was added to excite light emission. After optimisation of several parameters, the chemiluminescence method was used to determine the seven nitrofurans in animal feeds. Results showed that the method achieved ultrahigh sensitivity for the seven drugs with limits of detection of 5–12pgmL−1, and one assay was finished within 10min. In addition, the polymer-coated plate could be reused five times. The recoveries from the standard fortified blank feed samples were in the range of 74.8–97.4%. From a comparison with a high performance liquid chromatography method, the molecularly imprinted polymer based chemiluminescence method could be used as a simple, rapid, sensitive, and recyclable tool to monitor the abuse of nitrofurans in animal feeds.

Molecularly imprinted polymers for the detection of benomyl residues in water and soil samples

Benomyl is a benzimidazol fungicide used against various crop pathogens. Although banned in many countries, it is still widely used worldwide and is listed in different monitoring programs among the substances to be monitored to assess human exposure to pesticide residues. The assessment of benomyl is mainly based on the analysis of the residues of its most important metabolite, carbendazim. Existing methods often lack of selectivity and display a limited performance because of the presence of co-extracted compounds. Molecularly imprinted polymers (MIPs) offer an alternative methodology, adsorbing preferentially those target molecules for which the polymers are specifically prepared. In this study, we optimized the synthesis of a polymer imprinted with benomyl. Tests of specificity recognition showed a good performance for carbendazim compared with other similar pesticides. The mean recovery of benomyl (measured as carbendazim) from water samples was estimated to be 90% for MIPs while with real soil samples collected in Morocco the recovery efficiency was 62%. Preliminary tests also suggest that this MIP can implement traditional SPE techniques for assessing benomyl residual concentrations in environmental samples.

Preparation of a chemiluminescence sensor for multi-detection of benzimidazoles in meat based on molecularly imprinted polymer

In this study, a molecularly imprinted polymer capable of recognizing 8 benzimidazoles was first synthesized. The computation simulation showed that the shape and size of used template were the main factors influencing its recognition ability. Then the polymer was used as recognition reagent to prepare a chemiluminescence sensor on conventional 96-well microplate. The sample solution and a HRP-labeled hapten were added into the microplate wells to perform competitive binding, and the light signal was initiated with 4-(imidazol-1-yl)phenol enhanced luminol-H₂O₂ system. The optimized sensor was used to determine the residues of 8 benzimidazoles in mutton and beef. Result showed that the sensor achieved ultrahigh sensitivity (limits of detection of 1.5-21 pg/mL), rapid assay process (18 min) and satisfactory recovery (65.8%-91.2%). Furthermore, this sensor could be reused for 4 times. Therefore, this sensor could be used as a rapid, simple, sensitive and durable tool for screening the residual benzimidazoles in meat.

Synthesis and Characterization of a Molecularly Imprinted Polymer of Spermidine and the Exploration of Its Molecular Recognition Properties

Spermidine is a functional ingredient that can extend the lifespan of many foods and indicate meat safety. However, its synthesis and enrichment is expensive and complex. To develop an effective separation material that can offer highly selective recognition of spermidine, we first applied non-covalent molecular imprinting technology using methacrylic acid as a functional monomer, azobisisobutyronitrile as an initiator, and ethylene glycol dimethacrylate as a cross-linker. The adsorption properties of the polymers were analyzed using the Scatchard equation, the Lagergren kinetic equation, and the static distribution coefficient. The optimal polymerization molar ratio of the template molecule spermidine to the functional monomer was 1:4, the maximum adsorption amount was 97.75 μmol/g, and the adsorption equilibrium time was 300 min. The selective experiment showed that the interfering substances tyramine and histamine had selectivity factor α values of 2.01 and 1.78, respectively, indicating that the prepared polymer had good spermidine recognition ability. The density function theory calculations showed that the hydrogen bond strength, steric effect, and product energy caused adsorption and separation differences among the different imprinted polymer complexes.

Affinity Capillary Electrochromatography of Molecularly Imprinted Thin Layers Grafted onto Silica Capillaries Using a Surface-Bound Azo-Initiator and Living Polymerization

Molecularly imprinted thin layers were prepared in silica capillaries by using two different surface polymerization strategies, the first using 4,4'-azobis(4-cyanovaleric acid) as a surface-coupled radical initiator, and the second, S-carboxypropyl-S'-benzyltrithiocarbonate as a reversible addition-fragmentation chain transfer (RAFT) agent in combination with 2,2'-azobisisobutyronitrile as a free radical initiator. The ability to generate imprinted thin layers was tested on two different polymerization systems: (i) a 4-vinylpyridine/ethylene dimethacrylate (4VP-EDMA) in methanol-water solution with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a template; and (ii) methacrylic acid/ethylene dimethacrylate (MAA-EDMA) in a chloroform solution with warfarin as the template molecule. The binding properties of the imprinted capillaries were studied and compared with those of the corresponding non-imprinted polymer coated capillaries by injecting the template molecule and by measuring its migration times relative to a neutral and non-retained marker. The role of running buffer hydrophobicity on recognition was investigated by studying the influence of varying buffer acetonitrile concentration. The 2,4,5-T-imprinted capillary showed molecular recognition based on a reversed phase mechanism, with a decrease of the template recognition in the presence of higher acetonitrile content; whereas warfarin-imprinted capillaries showed a bell-shaped trend upon varying the acetonitrile percentage, illustrating different mechanisms underlying imprinted polymer-ligand recognition. Importantly, the results demonstrated the validity of affinity capillary electrochromatography (CEC) to screen the binding properties of imprinted layers.

Selective adsorption of carbohydrates and glycoproteins via molecularly imprinted hydrogels: application to visible detection by a boronic acid monomer

Molecularly imprinted PEG-based hydrogels were prepared for carbohydrates and glycoproteins. Visible detection of fructose was achieved by the gels.

From non-electroactive to electroactive species: highly selective and sensitive detection based on a dual-template molecularly imprinted polymer electrochemical sensor

A selective and sensitive detection of non-electroactive and electroactive molecules has been achieved on a dual-template imprinted electrochemical sensor. And the proposed dual-signal strategy can be used for highly sensitive detection of electroactive analytes.

Development of hydrophilic magnetic molecularly imprinted polymers by directly coating onto Fe3O4 with a water-miscible functional monomer and application in a solid-phase extraction procedure for iridoid glycosides

Development of hydrophilic magnetic molecularly imprinted polymers by directly coating onto Fe₃O₄ with a water-miscible functional monomer and application in a solid-phase extraction procedure for iridoid glycosides.