Molecularly Imprinted Polymers Materials Research Articles

Synthesis and Characteristics of Polymer-Mediated Curcumin Molecular Imprinting for Quantitative Determination of Curcumin in Food Samples

In this study, a molecularly imprinted polymer (MIP)-based extraction process for determining curcumin in food samples was carried out. MIP and NIP were thermally synthesized in acetonitrile solvent (porogen) using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linking agent, azobisisobutyronitrile as an initiator, and curcumin as a template molecule. Parameters affecting the synthesis process, such as temperature, the ratio of the components in the reaction, and the extraction solvent, were investigated. The characteristics of the synthesized material were examined using infrared spectroscopy and scanning electron microscopy. The maximum adsorption capacity of the material was found to be 1.34 mg/g MIP with an adsorption efficiency of 89.96% for MIP and 12.35% for NIP. The MIP material exhibited high selectivity for curcumin compared to other compounds such as quercetin (18.00%), rutin (14.74%), and ketoconazole (0.00%). The analysis method for curcumin using the MIP material was performed with validated parameters including linear range (1 – 25 mg/L, r2 = 0.9997), accuracy (recovery rate of 90.90 %), precision (RSDR = 0.338 %, RSDr = 1.591 %), detection limit (0.051 mg/L), and quantification limit (0.156 mg/L). The validation results indicated that the HPLC-DAD method was entirely suitable for analyzing the curcumin content in food samples.

Computational simulation-assisted design and experimental verification of molecularly imprinted polymers for selective extraction of chlorogenic acid

Chlorogenic acid (CGA) is an active ingredient in honeysuckle with a broad-spectrum of antibacterial activity, suppressing tumor growth and other pharmacological effects. However, it is susceptible to damage during traditional extraction and separation processes. Therefore, developing selective and efficient extraction methods of CGA is essential. Based on computational molecular simulations, a reliable and efficient molecularly imprinted polymers (MIPs) were successfully developed for selective extraction of CGA. MIPs and non-molecularly imprinted polymers (NIPs) were synthesized using a precipitation polymerization method, employing three different functional monomers: [methacrylic acid (MAA), 4-vinylpyridine (4-VP), and methyl methacrylate (MMA)], with CGA serving as the template molecule. To simulate the polymers and predict the optimal ratio between the template and functional monomer, the computational studies and adsorption performance experiments were carried out. The adsorption characteristics and thermal stability of polymers were evaluated by isothermal adsorption, adsorption kinetics, selective adsorption and thermogravimetric analysis, aiming to obtain the MIPs with specific recognition and selectivity for CGA. When the molar ratio of template CGA to functional monomer 4-VP was 1:8, the prepared MIPs was found to have the maximum adsorption capacity (14.85 mg g−1) and the highest imprinting factor (1.74) at the CGA concentration of 100 mg L−1. These results were consistent with those obtained by computational molecular simulation. This study not only provides good guidance for developing separation materials for extracting CGA from natural plants but also inspires the application of computer simulation and molecular docking techniques in the preparation of specific MIPs materials.

A melanin-integrated graphene quantum dots embedded molecularly imprinted polymer: A nano-fluorescence sensing probe for trace determination of prometryn

A nanocomposite fluorescence sensing probe was successfully designed and utilized for the ultrasensitive and highly selective determination of prometryn. The nanoprobe incorporated melanin nanoparticles, as an affinity material, and nitrogen-doped graphene quantum dots (N-GQDs) as fluorophores in molecularly imprinted polymers (MIP). Multiple techniques were employed to characterize the synthesized essential precursors and MIP fluorescent nanoprobe. The developed nanoprobe was then applied to detect prometryn, demonstrating linearity from 1.0 to 100.0 μg kg−1 with a limit of detection of 0.63 μg kg−1. When used to determine prometryn in real samples, the developed nanoprobe achieved recoveries from 92.4 % to 102.8 % with RSDs less than 5.4 %. The simplicity, reliability, selectivity and sensitivity of the proposed sensor indicated that the combination of MIP and eco-friendly materials produced an excellent fluorescent sensor for the detection of trace analytes.

Machine learning screening based strategy for the synthesis of a molecularly imprinted ionic liquid polymer for specific adsorption of perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that poses a significant environmental threat due to its resistance to degradation in both aquatic and terrestrial environments. Ionic liquids (ILs) are a type of salt that is liquid at or near room temperature and have been widely used in separation science, as well as showing great potential in environmental applications. However, the large number and variety of ILs make them impractical to assess the suitability of all possible ILs for PFOA adsorption using purely experimental methods. To address this issue, a high-throughput machine learning method was employed in this study to screen more than a thousand ILs and identify the most appropriate molecular for designing IL based molecularly imprinted polymer (MIP) with high affinity and selectivity of PFOA. The synthesized MIP, (Vim)C3(L-Pro)@MIP, has been proven to effectively and specifically recognize and adsorb PFOA in water. It has a maximum adsorption capacity of 568.18 mg g−1 and removal efficiency of over 99%, making it a highly efficient and selective option for PFOA removal in environmental remediation applications. This study showcases the promising potential of integrating high-throughput computer screening with experimental verification in the initial stages of MIP material design and development. By doing so, it is possible to create MIP materials that can effectively remove various pollutants, and potentially extend to other IL doped materials and applications.

SINTESIS DAN KARAKTERISASI MOLECULARLY IMPRINTED POLYMERS MENGGUNAKAN METIL METAKRILAT DAN ETILEN GLIKOL DIMETAKRILAT SEBAGAI ADSORBEN DI-(2-ETILHEKSIL) FTALAT (SYNTHESIS AND CHARACTERIZATION OF MOLECULARLY IMPRINTED POLYMERS USING METHYL METHACRYLATE AND ETHYLENE GLYCOL DIMETACRILATE AS ADSORBENT DI-(2-ETILHEKSIL) PHTHALATE)

Molecularly Imprinted Polymer (MIP) is an intelligent synthetic material because it has the ability to selectively recognize target molecules. This study aims to synthesize, characterize and analyze the performance of MIP. MIP material was synthesized using di-(2-Ethylhexyl) phthalate (DEHP) as a template molecule, methyl methacrylate (MMA) monomer combined with ethylene glycol dimethacrylate (EGDMA) as a crosslinker by precipitation polymerization method. MIP materials were characterized by SEM-EDS instrument, FTIR spectrometer, SAA instrument, and UV-Vis spectrophotometer. The test variables for the adsorption ability of MIP material on DEHP compounds were time and concentration. The results showed that the synthesized MIP was in the form of a coarse white solid with a stiff texture. Characterization with the EDS instrument showed a decrease in the mass percent of C and percent of C atoms which indicated the formation of MIP_DEHP_MMA-co-EGDMA(TE) and the surface morphology characterized by the SEM instrument was composed of small grains that tend to be uniform and have pores. The bonds that affect the formation of polymers characterized by FTIR were –C=C, –C=O, and –CO. Characterization with the SAA instrument was 142,2770 m2/g, the total pore volume was 0,2616 cm3/g and the average pore radius was 7.3562 nm, indicating mesoporous material. The optimum time for adsorption of MIP_DEHP_MMA-co-EGDMA(TE) to DEHP was 120 minutes. MIP_DEHP_MMA-co-EGDMA(TE) followed the pseudo-second-order kinetics model and the adsorption obeyed the Freundlich adsorption isotherm

Ethylphenidate determination in oral fluids by molecularly imprinted polymer extraction and ion mobility spectrometry

Drug abuse can be easily determined by oral fluid analysis, which allows the identification of the parent compounds instead of their respective metabolites, thus reducing potential misidentifications in other biological matrices. A molecularly imprinted polymer (MIP) has been synthetized by bulk polymerization to be employed in the selective extraction of ethylphenidate, a new psychoactive substance, in oral fluids. Ethylphenidate was employed as template molecule for the synthesis of MIP, and a non-imprinted polymer (NIP) was also synthesized. Scanning electron microscopy, nitrogen adsorption measurements and infrared spectroscopy were performed to characterize the resulting materials. A simple procedure was proposed based on the use of MIP as solid-phase extraction (SPE) sorbent for the target analytes in oral samples, followed by its determination by ion mobility spectrometry, providing a selective and sensitive methodology useful for a fast drug abuse identification. Selectivity of the MIP was evaluated by the extraction yield obtained for phenidate analogues and other conventional drugs, showing a reduced affinity for MIP material. The proposed ion mobility spectrometry (IMS) procedure has been validated in terms of selectivity, sensitivity, trueness, and precision, giving a limit of detection of 20 µg L−1 and quantitative recoveries from 82 to 91% in ethylphenidate spiked oral fluid samples.

Using magnetic nanoparticles/MIP-based electrochemical sensor for quantification of tetracycline in milk samples

This paper reports the development of a biomimetic sensor and its application for the determination of tetracycline antibiotics. Tetracycline is an extremely vital antibiotic usually used for the treatment of people and livestock with bacterial disorder and respiratory issues. This antibiotic is widely used in poultry farms for the prevention of bacterial infection and the treatment of advanced bacterial growth. The sensor was constructed using magnetic nanoparticles (mag) and molecularly imprinted polymer (MIP). Based on the application of the co-precipitation approach, FeCl3·6H2O and FeCl2·4H2O salts were used to obtain [email protected] magnetic nanoparticles. Prior to the synthesis of the selective MIP material, the density functional theory (DFT) was used to select the best functional monomer for the analyte investigated. After choosing the best monomer, the modified magnetic nanoparticles were used for the synthesis of the MIP in order to enhance the detection capability of the electrochemical sensor. The imprinted polymer was synthesized using optimized amounts of acrylic acid (functional monomer), ethylene–glycol-dimethacrylate (cross-linker), and 2,2 azobisisobutyronitrile (radical initiator). The control material – denoted by mag-NIP (magnetic non-molecularly imprinted polymer), which was used for comparison purposes, was synthesized based on the same procedure applied for the synthesis of the MIP but in the absence of the analyte (tetracycline). The analysis of surface morphology and the identification of the functional groups used in the synthesized magnetic materials were performed by fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and high-resolution electron microscopy. The detection of tetracycline was performed under optimized conditions using square wave voltammetry, 15 mg of mag-MIP (on carbon paste), and 80 s of pre-concentration. Through the application of this analysis, well-defined peaks ranging from 0.5 to 1.0 V vs. Ag/AgCl (KClsat) were obtained. Analytical curves were constructed using the second peak at 0.83 V, and the following results were obtained: linear range of 5.0 × 10−7 to 4.0 × 10−5 mol L−1 (R2 of 0.9993), limit of detection (LOD) of 1.5 × 10−7 mol L−1 and repeatability of 2.82% (in terms of relative standard deviation) for n = 10. The results obtained from the analysis of selectivity demonstrated that the proposed electrochemical sensor is highly efficient for tetracycline determination. The sensor was successfully applied in commercial and raw milk samples for tetracycline detection, and recovery rates ranging from 93 − 103% were obtained. The results obtained show that the proposed electrochemical technique is suitable for application toward the determination of tetracycline.

Preparation, characterization and evaluation of a styrene-based molecularly imprinted polymer for capturing pyridine and pyrrole from crude oil

The rapid increase in global energy demand met with fossil fuel exploration and use as an energy source has not been achieved without its impacts on human and environmental health. Consequently, the imposition of stricter measures on key pollution sources in the effort to reduce the emission of contaminants into the environment became necessary. In this work, a new molecularly imprinted polymer (MIP) targeting pyridine (pyd) and pyrrole (pyr) was synthesized using styrene as a functional monomer. MIP and the non-imprinted polymer (NIP) were characterized by infrared spectroscopy, x-ray spectroscopy, and scanning electron microscopy. The polymer had spongy surfaces and porous network structures. The effects of several factors, such as initial analyte concentration, contact time, and adsorbent dose on pyd and pyr removal efficiencies from crude oil were evaluated. Quantitative analyses indicated that the removal of pyd and pyr occurred at fast kinetics, with a removal efficiency of 15.12 and 15.33, respectively, after 10 min of adsorption time. Optimum adsorption for both analytes was however not reached until 420 min, indicating slow kinetics. The uptake of the analytes increased with a rise in concentration. The highest removal percentages were recorded at 99.9% and 99.7% for pyd and pyr respectively, at 0.06 mol dm−3 adsorbate concentration of the modeling organic media. Two adsorption isotherm models were applied to analyze the equilibrium data, obtaining the best description by the Freundlich isotherm model. The accuracy of the MIP materials was validated using Bonny crude oil from Nigeria. The results showed that the MIP was effective for the adsorption of pyd and pyr in both modeling organic media and real crude oil.

Plastic Antibody of Polypyrrole/Multiwall Carbon Nanotubes on Screen-Printed Electrodes for Cystatin C Detection.

This work reports the design of a novel plastic antibody for cystatin C (Cys-C), an acute kidney injury biomarker, and its application in point-of-care (PoC) testing. The synthetic antibody was obtained by tailoring a molecularly imprinted polymer (MIP) on a carbon screen-printed electrode (SPE). The MIP was obtained by electropolymerizing pyrrole (Py) with carboxylated Py (Py-COOH) in the presence of Cys-C and multiwall carbon nanotubes (MWCNTs). Cys-C was removed from the molecularly imprinted poly(Py) matrix (MPPy) by urea treatment. As a control, a non-imprinted poly(Py) matrix (NPPy) was obtained by the same procedure, but without Cys-C. The assembly of the MIP material was evaluated in situ by Raman spectroscopy and the binding ability of Cys-C was evaluated by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) electrochemical techniques. The MIP sensor responses were measured by the DPV anodic peaks obtained in the presence of ferro/ferricyanide. The peak currents decreased linearly from 0.5 to 20.0 ng/mL of Cys-C at each 20 min successive incubation and a limit of detection below 0.5 ng/mL was obtained at pH 6.0. The MPPy/SPE was used to analyze Cys-C in spiked serum samples, showing recoveries <3%. This device showed promising features in terms of simplicity, cost and sensitivity for acute kidney injury diagnosis at the point of care.

Core–shell Ag-dual template molecularly imprinted composite for detection of carbamate pesticide residues

Carbamate pesticides are popularly used in agriculture due to their relatively low toxicity and their more degradable nature compared to organophosphates. Resultant residues pose a threat to human and animal health, aquatic systems and wildlife. Carbaryl and thiodicarb are used to control pests in a variety of agricultural crops. Monitoring the level of these pesticides in the environment is crucial in ensuring environmental safety. Multi-template imprinted polymers combined with surface enhanced Raman spectroscopy (SERS) are attractive for sensitive and effective multiple analyte detection for application in pesticide residue studies in environmental matrices. A core–shell Ag-dual template molecularly imprinted polymer (MIP) composite was synthesized and evaluated in this study. Computational design was used to study intermolecular interactions in the pre-polymerization mixture between methylacryamide (MAM) (functional monomer) and the templates carbaryl (CBL) and thiodicarb (TDC). The interaction between the computer simulated template-functional monomer complexes was evaluated by examining the hydrogen bonds to provide insights on the observed binding performance of the dual imprinted polymer. The MIP was then synthesized and its binding properties towards CBL and TDC investigated experimentally. More so, we compared the performance of the mono-template MIP materials and the dual-template MIP material in detection of the templates. The experimental results corroborate the computer simulation results and reveal that CBL has higher adsorption capacity as supported by higher number of hydrogen bonds in the template monomer complex. Therefore, the study presents a cost-effective approach that utilizes a dual-template imprinted polymer for detection of carbamate pesticide residues.

Enabling the Selective Detection of Endocrine-Disrupting Chemicals via Molecularly Surface-Imprinted "Coffee Rings".

Molecularly imprinted polymers (MIPs) represent an intriguing class of synthetic materials that can selectively recognize and bind chemical or biological molecules in a variety of value-added applications in sensors, catalysis, drug delivery, antibodies, and receptors. In this context, many advanced methods of implementing functional MIP materials have been actively studied. Herein, we report a robust strategy to produce highly ordered arrays of surface-imprinted polymer patterns with unprecedented regularity for MIP-based sensor platform, which involves the controlled evaporative self-assembly process of MIP precursor solution in a confined geometry consisting of a spherical lens on a flat Si substrate (i.e., sphere-on-flat geometry) to synergistically utilize the "coffee-ring" effect and repetitive stick-slip motions of the three-phase contact line simply by solvent evaporation. Highly ordered arrays of the ring-patterned MIP films are then polymerized under UV irradiation to achieve semi-interpenetrating polymer networks. The extraction of templated target molecules from the surface-imprinted ring-patterned MIP films leaves behind copious cavities for the recognizable specific "memory sites" to efficiently detect small molecules. As a result, the elaborated surface structuring effect, sensitivity, and specific selectivity of the coffee-ring-based MIP sensors are scrutinized by capitalizing on an endocrine-disrupting chemical, 2,4-dichlorophenoxyacetic acid (2,4-D), as an example. Clearly, the evaporative self-assembly of nonvolatile solutes in a confined geometry renders the creation of familiar yet ordered coffee-ring-like patterns for a wide range of applications, including sensors, scaffolds for cell motility, templates, substrates for neuron guidance, etc., thereby dispensing with the need of multistep lithography techniques and external fields.

Theoretical and experimental studies of a novel electrochemical sensor based on molecularly imprinted polymer and GQDs-PtNPs nanocomposite

A new molecularly imprinted polymer (MIP) electrochemical sensor was prepared applying one-step electro-copolymerization of 3, 4-ethylenedioxythiophene (EDOT) and methacrylic acid (MAA) in the presence of sulfadimidine as a template molecule on a glassy carbon electrode (GCE) which modified with graphene quantum dots (GQDs)-Pt nanoparticles (PtNPs). A computational approach was employed to screen the suitable functional monomer, and the simulation data suggested that EDOT and MAA as bifunctional monomers exhibited a preferable capability to recognize the target molecule compared to other monomers. The MIP material was characterized with scanning electron microscope (SEM), transmission electron microscope (TEM) and electrochemical impedance spectroscopy (EIS). The performance of MIP sensor was evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results indicated that the electro-copolymerization of EDOT and MAA provides large amounts of functional groups for the binding of the template molecules, which significantly enhances the sensitivity of the MIP sensor. The calibration curve demonstrated linearity over a concentration range of 0.1 nM-0.1 mM with a detection limit of 0.023 nM. This study provides complete and valuable information on the rational design, preparation, and application of sulfadimidine molecularly imprinted polymers using advanced materials and new bi-functional monomers.

Growing Trends in the Efficient and Selective Extraction of Compounds in Complex Matrices Using Molecularly Imprinted Polymers and Their Relevance to Toxicological Analysis

In the world of forensic and clinical toxicology, proper sample preparation is one of the key steps in identification and quantification of drugs of abuse. Traditional extraction methods such as solid-phase extraction and liquid-liquid extraction are often laborious and nonselective for the target analytes being measured. Molecularly imprinted polymers (MIPs) can be synthesized for sample extraction and their versatility allows the polymer to be employed in off-line, benchtop extractions or on/in-line instrument extractions, offering a faster and more selective sample preparation without the risk of interfering matrix effects. This review details the synthesis and applications of MIP materials for the extraction of drug compounds from biological matrices in publications from 1994 to today.

Preparation of molecularly imprinted polymers for sensing of 2,4-dichlorophenoxyacetic acid residues in environmental water and mixed juice

In this paper, we reported a rapid and simple approach to synthesize molecularly imprinted polymers (MIPs) materials for sensing of 2,4-dichlorophenoxyacetic acid (2,4-D) residues in environmental water and mixed juice. Initially, MIPs materials were prepared via visible light-initiated reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization at ambient temperature using 2,4-D and its analogs as template molecules, in which 4-vinyl pyridine (4-VP), ethylene glycol dimethacrylate (EGDMA), (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO), 2-(((dodecylthio)carbonothioyl)thio)-2-methylpropanoic acid (DDMAT) were functional monomer, cross-linker, visible light initiator and RAFT agent, respectively. Then, the morphologies of the MIPs materials were characterized by FT-IR, SEM and DLS. The results showed that the MIPs materials were well-distributed spherical particles with sizes ranging from 1 to 2 μm. Furthermore, a four-channel MIPs sensor array included four polymer microspheres with a fluorescent dye displacement procedure was developed to distinguish the templates and their chemical analogs at the ppm concentration level. With the support of principal component analysis and hierarchical cluster analysis, the four-channel MIPs sensor array proves to be a simple and effective method to recognize and distinguish the templates and nontemplates in aqueous solution with 100% accuracy. Finally, the four-channel MIPs sensor array was also found to have satisfactory accuracy in monitoring 2,4-D contaminated environmental water and mixed juice.

Dual biorecognition by combining molecularly-imprinted polymer and antibody in SERS detection. Application to carcinoembryonic antigen

This work reports the innovative combination of a molecularly-imprinted polymer (MIP) and a natural antibody for the accurate surface-enhanced Raman spectroscopy (SERS) detection of carcinoembryonic antigen (CEA). The MIP material acted as a pre-concentration scheme for the target protein, while the natural antibody was responsible to signal the presence of CEA on the MIP platform.Gold-based screen-printed electrodes were used as substrate and gallic acid (GA) was used herein for the first time in the assembly of a MIP film, by electropolymerization, in the presence of CEA. This layer was further covered by a second ultra-thin film of electropolymerized benzoic acid (BA), to avoid non-specific binding. The rebinding features of the MIP film were evaluated by electrochemical impedance spectroscopy (EIS) and a linear response was observed from 1 to 1000 ng/mL.For a sensitive SERS detection, the MIP film was first incubated in sample containing CEA and next incubated in SERS tag. For the SERS tag, gold nanostars (AuNSs) were employed as metal support, coupled to 4-aminothiophenol (4-ATP) as Raman reporter and to a natural antibody for CEA as recognition element. The overall system showed a sensitive response down to 1.0 ng/mL, which was different from the blank signal.Overall, the innovative approach presented herein combines the advantages of using two different targeting elements for CEA. The costs and time of MIP production were substantially low due to selection of electropolymerization approach and the proposal described herein may be extended to other target molecules.

Molecularly Imprinted Polymer Materials as Selective Recognition Sorbents for Explosives: A Review.

Explosives are of significant interest to homeland security departments and forensic investigations. Fast, sensitive and selective detection of these chemicals is of great concern for security purposes as well as for triage and decontamination in contaminated areas. To this end, selective sorbents with fast binding kinetics and high binding capacity, either in combination with a sensor transducer or a sampling/sample-preparation method, are required. Molecularly imprinted polymers (MIPs) show promise as cost-effective and rugged artificial selective sorbents, which have a wide variety of applications. This manuscript reviews the innovative strategies developed in 57 manuscripts (published from 2006 to 2019) to use MIP materials for explosives. To the best of our knowledge, there are currently no commercially available MIP-modified sensors or sample preparation methods for explosives in the market. We believe that this review provides information to give insight into the future prospects and potential commercialization of such materials. We warn the readers of the hazards of working with explosives.

Advanced preparation technologies and strategies for molecularly imprinted materials

Molecularly imprinted polymers (MIPs) prepared by molecular imprinting technology (MIT) are polymers with specific recognition sites matching the shape, size and functional groups of template molecules, which can selectively identify and enrich target analytes (template molecules), and have been widely used in sample pretreatment, chemical/biological sensing and other fields. However, in the processes of preparation and applications of MIPs, there are still some problems, such as difficult elution of template molecules, fewer effective recognition sites, low binding capacity, low mass transfer rate and poor recognition in aqueous media. As a multidisciplinary technology, MIT has developed rapidly by borrowing and integrating related advanced technologies/strategies of other fields. Consequently, a variety of new imprinting technologies and strategies have continuously emerged, which not only effectively solve the abovementioned problems but also push forwards the development of novel MIPs and widen their applications. In this paper, orienting the applications of MIPs in sample pretreatment, sensors and stimuli responses, some advanced preparation technologies and strategies for MIPs materials are highlighted, including ingenious imprinting technologies (surface imprinting, nanoimprinting; controlled/living polymerization, solid-phase synthesis, etc.), special imprinting strategies (multi-template/monomer imprinting, dummy imprinting, boronate affinity imprinting, etc.), and stimuli-responsive imprinting (magnetic, temperature, pH responsive, etc.). Fundamental features of the advanced imprinting technologies/strategies and their utilizations for MIPs preparations along with representative applications are described in details, involving important issues and research challenges. Firstly, a comprehensive overview of main imprinting technologies and strategies for MIPs preparation in sample pretreatment application is provided. In this regard, MIPs are used as selective adsorbents of various extraction technologies such as solid-phase extraction (SPE), dispersive SPE and magnetic SPE. Aiming at high selectivity and high adsorption capacity, the MIPs should have ideal morphology, uniform size and excellent surface properties. Besides conventional preparative methods, it is required to introduce new imprinting technologies and strategies, mainly including the ingenious imprinting technologies of surface imprinting, nanoimprinting, controlled/living free radical polymerization (CLRP), click chemistry, hollow porous polymer synthesis technology and solid-phase synthesis, and the special imprinting strategies of multi-template/monomer imprinting, dummy/segment imprinting, magnetic material and boronate affinity imprinting. Surface imprinting and nanoimprinting technologies are usually adopted by coupling with the abovementioned imprinting technologies and strategies. Secondly, advanced imprinting technologies and strategies for the construction of MIPs-based sensors are summarized. For the sensors, the MIPs as recognition elements can specifically bind target analytes and as transduction elements can generate output signals for detection. Typically, the output detection signals can be classified into three types, electrochemical, optical and piezoelectric types according to the transduction mechanism; molecular imprinting based electrochemistry, fluorescence and surface enhanced Raman scattering sensors are the research hotspots. For sensing applications, it is necessary to consider the main parameters such as response time, linear dynamic range, sensitivity, selectivity and reproducibility. Therefore, the MIPs should have excellent interface properties by employing appropriate preparative technologies and strategies. Nanoimprinting, surface imprinting and composite material imprinting strategy have become the preferences. Herein, constructions of molecular imprinting fluorescence sensors are emphatically introduced, especially ratiometric fluorescence ones. Thirdly, the imprinting technologies and strategies orienting stimuli-responsive application are briefly introduced, for preparing stimuli-responsive MIPs (SR-MIPs) with specific recognition ability toward targeted molecules under stimuli-regulation and thereby achieving intelligent control. SR-MIPs are able to sensitively respond to specific external physicochemical/biological stimuli with a considerable and reversible change in their properties, such as molecular chain structure, solubility, swelling or dissociation behavior, resulting in regular changes of imprinting properties. The most reported magnetic, temperature, photonic and pH sensitive SR-MIPs and their dual or multi stimuli responsive SR-MIPs are reviewed. The rapid development of smart ecofriendly SR-MIPs and their stimuli-responsive application will accelerate the drug delivery application and assist the widely carried out sample pretreatment and sensors applications. Lastly, future perspectives of MIT and MIPs are proposed. In order to solve the core issues of selectivity, mass transfer rate and adsorption capacity of MIPs, it is imperative to rationally combine various imprinting technologies and strategies. The ingenious fusion of MIT and various advanced technologies should be continuously strengthened to promote the preparation of MIPs materials.

Dopamine-based molecularly imprinted polymers for the recognition of biomacromolecules

Compared to natural antibodies or receptors, molecularly imprinted polymers (MIPs) have shown advantages of easy preparation, low cost, high stability and reusability. MIPs have been widely used in the fields of separation, chemical sensing, drug delivery and biocatalysis. The development of new imprinting methods such as surface imprinting, epitope imprinting, post-imprinting modification have promoted the synthesis and application of MIPs against biomacromolecules. Despite of the success, it remains a challenge to prepare MIPs with high affinity and specificity to the target proteins because the options of water-soluble monomers are very limited and the protein’s conformation is liable to change during the polymerization reaction. The majority of protein imprinting studies employ the five most common monomers: acrylamide (AAm), methacrylic acid (MAA), aminophenylboronic acid (APBA), acrylic acid (AA), and N-isopropylacrylamide (NiPAAm) and the two frequently used crosslinkers, methylenebisacrylamide (MBA) and ethylene glycol dimethacrylate (EGDMA) for preparation of protein imprinted polymers. In recent years, dopamine (DA) has been frequently used for surface modification as it can self-polymerize in alkaline medium at room temperature and generate polydopamine (pDA) films that can adhere onto almost all inorganic and organic surfaces with good biocompatibility. Thus, DA emerged as an appropriate monomer as well as a crosslinker for various imprinting reactions. In this review, we highlighted the recent advances in design and fabrication of DA-based MIPs for various biomacromolecules, including proteins, glycoproteins, bacteria or virus, with focus on protein imprinted polymers. First, we briefly introduced the DA self-polymerization reaction and the reported mechanisms for pDA formation. It is generally accepted that the initial driving force for the formation of pDA is the oxidation of DA to DA-indole by dissolved oxygen in an alkaline solution. Then, we summarized the recent work that employs common protein such as human/bovine serum albumin (HSA/BSA), lysozyme (Lyz), hemoglobin, trypsin and immunoglobulin (IgG) as the imprinting templates. These MIPs were mainly used for separation and purification of the template proteins. We also introduced the combination of protein imprinting with quartz crystal microbalance (QCM), cyclic voltammetry (CV), surface plasmon resonance (SPR) and mass spectroscopy (MS) for recognition and detection of the target proteins. In the following part, we summarized the strategies developed for imprinting of glycoproteins, most of which took advantage of boron affinity reaction or lectin-sugar interaction to improve the affinity and selectivity of the resultant MIPs. Then, we introduced recent work on imprinting of microorganisms such as viruses and bacteria, in which surface imprinting technique and potential analysis or chemiluminescence (ECL) technique are combined to construct biosensors that can selectively detect target species with high sensitivity. In addition, we also introduced the synthesis of a bio-inspired virus imprinted polymer and its application for prevention of viral infections. The techniques which were used for characterizing the properties of the MIP materials, e.g., adsorption capacity, imprinting factor and selectivity, as well as the proposed theoretical model were also mentioned in the review. Finally, we discussed current challenges and possible solutions for using DA as a monomer to prepare MIPs for biomacromolecules. We believe that the interactions between the intermediate products during dopamine polymerization and the template proteins deserve further investigation, as it may provide more possibilities to modulate the binding properties of the obtained MIPs.

Development of water-compatible molecularly imprinted solid-phase extraction coupled with high performance liquid chromatography–tandem mass spectrometry for the detection of six sulfonamides in animal-derived foods

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.

Application of Polymethacrylic Acid Imprinted Quartz Crystal Microbalance Sensor for Detection of 3-Carene in Mango

This paper aims to develop a selective molecularly imprinted polymer (MIP) layer combined with quartz crystal microbalance sensor for the detection of 3-Carene, a significant aroma compound of mango. The proposed sensor is prepared from the co-polymer of methacrylic acid and divinylbenzene, and it is imprinted with 3-Carene. The MIP template was synthesized and deposited onto the quartz crystal microbalance platform by proper functionalizing the gold electrode using 2-propene 1- thiol. The developed MIP material is characterized by fourier transform infra-red, scanning electron microscope, and atomic force microscope techniques. The sensor offers very good selectivity and sensitivity (1–1000 ppm) of 0.11 Hz/ppm to 3-Carene from its structural analogies. The limit of detection and the limit of quantitation of the sensor are found to be 0.8 and 1.4 ppm, respectively. The performance of the sensor offers satisfactory reproducibility and repeatability to 3-Carene. Moreover, the response of the sensor has been correlated to the standard gas- chromatography-mass spectrometry data to detect 3-Carene in Langda and Chausa mango.