Development of a semiautomated procedure for the synthesis and evaluation of molecularly imprinted polymers applied to the search for functional monomers for phenytoin and nifedipine

Preparation of molecularly imprinted polymer for the specific adsorption and selective extraction of alkylresorcinols from whole wheat flour

Alkylresorcinols are important biomarkers for evaluating whole wheat foods. However, their structures encompass a broad spectrum of homologs, making isolating and analyzing individual alkylresorcinol notably challenging. Herein, we synthesized highly selective molecularly imprinted polymers (MIPs) utilizing a facile and cost-effective precipitation polymerization method and 5-heneicosylresorcinol (ARC21:0) as the template molecule. Various crucial preparation parameters were systematically optimized, such as different porogens, functional monomers, imprinting ratios, and polymerization time. The polymers were characterized through scanning electron microscopy and Fourier transform infrared spectroscopy, and their adsorption performances were thoroughly evaluated. MIPs exhibited a notably enhanced adsorption capacity compared with that of non-imprinted polymers, reaching an optimal adsorption amount of 71.75 mg·mL-1 and imprinting factor of 2.02. Altogether, the synthesized MIPs showed superior affinity and selectivity for ARC21:0, as confirmed by their selective extraction, suggesting their potential applications in the analysis, separation, and monitoring of ARC21:0 in whole wheat foods.

A Smartphone-Integrated Ratiometric Fluorescence Sensor for the Ultrasensitive and Selective Detection of 5-Heneicosylresorcinol in Whole Wheat Foods

Precise on-site monitoring of alkylresorcinols, a vital biomarker, is crucial for verifying whole wheat foods and accurately quantifying the whole wheat content in various consumer and industrial products. Herein, for the first time, we introduce a novel ratiometric fluorescence sensor (CDs@ZIF-8/CdTe@MIP) for ultrasensitive and selective detection of alkylresorcinols. 5-Heneicosylresorcinol (C21:0 AR), the primary alkylresorcinol homologue in whole wheat grains, was selected as the target analyte. This analyte was specifically and selectively recognized by the incorporation of a molecularly imprinted polymer (MIP) layer. Within this nanoreactor, blue-emitting carbon dots embedded in zeolitic imidazolate framework-8 (CDs@ZIF-8) and orange-emitting CdTe quantum dots served as the self-calibration signal and response signal, respectively. Exploiting a photoinduced electron transfer effect between CdTe and C21:0 AR, the established fluorescence sensor exhibited remarkable sensing performance, offering wide linear responses in 0.005-1 μg·mL-1 and 1-80 μg·mL-1 concentration ranges, and achieving a low detection limit of 1.14 ng·mL-1. The proposed assay effectively detected C21:0 AR in real samples, including 8 whole wheat foods and 19 whole wheat grains, demonstrating good recoveries and relative standard deviation. Furthermore, an intelligent sensing platform was established by integrating CDs@ZIF-8/CdTe@MIP with a smartphone-assisted device, thus validating the feasibility of visual and on-site monitoring of C21:0 AR. Because of its rapid response, portability, cost-effectiveness, superior sensitivity, and high selectivity, the proposed sensor serves as a reliable method for the analysis of C21:0 AR, thus having substantial potential for on-site monitoring of whole wheat foods.

Synthesis, delivery, and molecular docking of fused quinolines as inhibitor of Hepatitis A virus 3C proteinase

It is widely accepted that Hepatitis A virus (HAV) is responsible for liver failure and even death in older people and in people with other serious health issues; so, proposing new compounds with inhibitory activity can help to treated of these disease’s. In current study, a new class of quinolines is proposed with inhibitor activity of the HAV proteinase. So, in the first step, fused quinoline derivatives has been synthesized in short reaction time (12.0 min) and high efficiency yields (94%) in presence of 1-carboxymethyl-2,3-dimethylimidazolium iodide ([cmdmim]I) ionic liquid catalyst using a new method. In the following, chemical reactivity and inhibitory activity of synthesized quinolines were evaluated in density functional theory (DFT) framework and molecular docking methodologies. High global softness (0.67 eV), low HOMO_SWBNNT-LUMO_4a gap (4.78 eV), and more negative adsorption energy (− 87.9 kJ mol⁻¹) in these quinolines reveal that the 4a and 4b compounds have better delivery than other quinolines using SWBNNT as suitable carrier to target cells. Molecular docking shows that the best cavity of the HAV has − 134.2 kJ mol⁻¹ interaction energy involving bonding and non-bonding interactions. In fact, these interactions are between fused quinolines with especial geometries and sidechain flexibility amino acids residues inside the best binding site of the HAV, as hydrogen bonding, steric, and electrostatic interactions. So, these interactions imply that proposed fused quinolines have good inhibitor activity for the HAV.

Synthesis of a nano molecularly imprinted polymeric sorbent for solid phase extraction and determination of phenytoin in plasma, urine, and wastewater by HPLC

In this work a nano polymeric sorbent for phenytoin was synthesized by non-covalent molecularly imprinted polymerization approach.

Rational synthesis of pindolol imprinted polymer by non-covalent protocol based on computational approach

Pindolol (PDL) is a potent and specific adrenoreceptor blocking agent. It is widely used in the treatment of hypertension, cardiac arrhythmia and angina pectoris. Molecularly imprinted polymers (MIPs) are synthetic receptors having potential applications in drug delivery systems and devices such as diagnostic sensors. In the present work, ab initio quantum mechanical simulations and computational screening were used to identify functional monomer having best interactions with PDL. A virtual library of 16 functional monomers was built and the possible minimum energy conformation of the monomers and PDL were calculated using Hartree-Fock (HF) method for the synthesis of PDL imprinted polymer. The interaction energy between functional monomer and the template were corrected by means of basis set superposition error (BSSE) in all pre-polymerization complexes. The hydrogen bonding between PDL and functional monomer was evaluated by changes in bond lengths before and after complex formation. The virtual template-monomer complex with highest interaction energy is more stable during the polymerization and leads to high selectivity and specificity toward the template. The interaction energy of PDL was found to be the highest with itaconic acid followed by 4-vinyl pyridine and least with acrylonitrile. Taking a spectroscopic viewpoint, results obtained from analysis of the harmonic infrared spectrum were examined. Red and blue shifts related to the stretching frequencies of either donors or acceptors of protons were identified and compared experimentally. Stoichiometric mole ratio of template to functional monomer was optimized and confirmed by UV visible spectra titrations. The theoretical results were correlated by evaluation of binding parameters of MIPs. The experimental binding results were in good agreement with theoretical computations.

Ultrasensitively sensing acephate using molecular imprinting techniques on a surface plasmon resonance sensor

An ultrathin molecularly imprinted polymer film was anchored on an Au surface for fabricating a surface plasmon resonance sensor sensitive to acephate by a surface-bound photo-radical initiator. The polymerization in the presence of acephate resulted in a molecular-imprinted matrix for the enhanced binding of acephate. Analysis of the SPR wavenumber changes in the presence of different concentrations of acephate gave a calibration curve that included the ultrasensitive detection of acephate by the imprinted sites in the composite, K(ass) for the association of acephate to the imprinted sites, 7.7×10(12) M(-1). The imprinted ultrathin film revealed impressive selectivity. The selectivity efficiencies for acephate and other structurally related analogues were 1.0 and 0.11-0.37, respectively. Based on a signal to noise ratio of 3, the detection limits were 1.14×10(-13) M for apple sample and 4.29×10(-14) M for cole sample. The method showed good recoveries and precision for the apple and cole samples spiked with acephate solution. This suggests that a combination of SPR sensing with MIP film is a promising alternative method for the detection of organophosphate compounds.

Quantitative structure-imprinting factor relationship of molecularly imprinted polymers

Computational approach for evaluating the feasibility of template-monomer complexes has great potential in assisting the selection of appropriate functional monomers for template molecule of interest. A quantitative structure-property relationship (QSPR) study of template-monomer complexes was investigated for the prediction of imprinting factor of molecularly imprinted polymers (MIPs). The data set was based on uniformly-sized MIP particles taken from the literature and was used in our previous study for computing the imprinting factor using molecular descriptors derived from charge density-based electronic properties of molecules. In this study, we examined the feasibility of using quantum chemical descriptors and artificial neural networks for prediction of the imprinting factor. The proposed methodology reliably predicted the imprinting factor of MIPs with correlation coefficient from 0.7083 to 0.8378 albeit to a lesser degree than charge-based descriptors, which yielded correlation coefficient as high as 0.9680. The importance of mobile phase descriptors on the predictive performance of the QSPR model has surprisingly shown that the use of mobile phase descriptors alone was able to predict the imprinting factor with good performance.

Influence of initiator and different polymerisation conditions on performance of molecularly imprinted polymers

A set of polymers was imprinted with (-)-ephedrine using two different initiators. A chemometrics approach was used to optimise experiments aimed at analysis of the interplay of parameters such as polymerisation time, temperature and percentage of initiator. The results presented demonstrate the importance of keeping the right balance between these various parameters of polymerisation conditions. It is shown that enhancing one single parameter such as polymer rigidity does not necessarily improve polymer performance. In general it could be concluded that MIPs should be synthesised over a long period of time using low concentration of initiator and low temperature. The best selectivity was achieved for polymers prepared by photo-initiation with 2,2-dimethoxy-2-phenylacetophenone as initiator.

Direct rapid synthesis of MIP beads in SPE cartridges

Selecting optimal compositions for non-covalent molecularly imprinted polymers (MIPs) and screening for appropriate rebinding conditions necessitates synthesising a large number of polymers. This is extremely labour-intensive and usually results in very limited "optimisation" in studies of MIPs. Here, a new method is proposed for rapid synthesis of MIPs in a beaded form that can be used directly in many different performance evaluation studies. The method is based on synthesis of spherical particles by suspension polymerisation in liquid fluorocarbon [Mayes, A., Mosbach, K., 1996. Molecularly imprinted polymer beads: suspension polymerisation using a liquid perfluorocarbon as the dispersing phase. Anal. Chem. 68, 3769-3774]. The polymers were directly polymerised under UV light in solid phase extraction (SPE) cartridges, then washed and extracted in the same cartridges where they had been synthesised, resulting in a rapid and automatable process that requires no transfer or manipulation of the polymer particles. The particles were similar in terms of size, morphology and functional performance to particles obtained by suspension polymerisation in fluorocarbon solvent using a conventional reactor. In this initial study, 36 polymers were synthesised to study the effect of a variation in the type and amount of four different functional monomers, methacrylic acid (MAA), acrylic acid (AA), hydroxyethyl methacrylate (HEMA) and 2-vinylpyridine (2-VPy), for the imprinting of propranolol and morphine. The performance of polymers synthesised using MAA was as expected, but those synthesised with AA as functional monomer showed more surprising rebinding properties as a function of monomer to cross-linker ratios, demonstrating the potential value of pragmatic synthesis and screening approaches to polymer optimisation.

Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003

Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.

Chromatographic behavior of silica–polymer composite molecularly imprinted materials

Molecularly imprinted polymers (MIP) have recently been prepared inside the pores of silica based HPLC packing materials. Detailed physical and chromatographic characterization of such a silica-MIP composite material is presented. The chromatographic peak shape obtained with the uniformly sized spherical silica-MIP composite is mainly determined by the nonlinear adsorption isotherm. Comparison of the composite with the conventional sieved and grinded bulk MIP is therefore based on the nonlinear isotherm and not on retention factors and plate numbers.

Simultaneous determination of phenytoin, barbital and caffeine in pharmaceuticals by absorption (zero-order) UV spectra and first-order derivative spectra--multivariate calibration methods

The quantitative predictive abilities of partial least squares (PLS-1) and principle component regression (PCR) on absorption (zero-order) UV spectra are compared with the results obtained by the use of these multivariate calibration methods on first-order derivative spectra. Both approaches were satisfactorily applied to the simultaneous determination of these drugs in synthetic and pharmaceutical mixtures. Significant advantages were found in the simultaneous determination of phenytoin, barbital and caffeine in binary and ternary mixtures, by application of different multivariate calibration methods when the calibration matrix was performed using the first-order derivative spectra. The proposed method was validated by applying it to the analysis of binary and ternary mixtures of phenytoin, barbital and caffeine. Determinations were made over the concentration ranges of 0.24-22.0, 0.01-27.0 and 0.049-27.0 microg ml(-1) for phenytoin, barbital and caffeine, respectively, in the binary and 0.45-22.0, 0.05-26.0 and 0.05-20.0 microg ml(-1) for phenytoin, barbital and caffeine, respectively, in the ternary mixtures. The relative standard errors in the determinations were less than 3% in most cases.

Improved Imide Receptors by Imprinting Using Pyrimidine-Based Fluorescent Reporter Monomers

[reaction: see text] Optically responsive receptors toward imides based on 6-substituted 2,4-bis(acrylamido)pyrimidines are presented. The monomers were readily prepared in good yield. Solution binding to 1-benzyluracil (BU) monitored by 1H NMR appeared lower than a previously reported pyridine-based monomer. However, as indicated by 1H NMR and IR spectral investigations, the association strength was demonstrated to be "masked" by dimerization of the pyrimidine-based monomer units. Thus, from dilution experiments, a dimerization constant of 731 M(-1) was estimated for the pyrimidine-based monomer 2,4-bis(acrylamido)-6-piperidinopyrimidine whereas for the pyridine-based monomer 2,6-bis(acrylamido)pyridine, no self-association was observed. This precluded an accurate determination of the binding constant for BU to the former monomer whereas for the latter a binding constant of 757 M(-1) was measured. Despite the strong self-association, the novel monomer was shown to lead to enhanced imprinting effects when compared to imprinted polymers prepared analogously, but using the pyridine-based monomer as the recognition element. This was attributed to a higher intrinsic binding affinity exhibited by the pyrimidine based host monomer vis a vis the guest and the existence in the former of more than one interaction site for the guest. The monomers exhibited fluorescence emission informative of the mode of monomer incorporation in the polymer and the presence of guest species. Thus, the fluorescence was rapidly and selectively quenched upon template addition, with the degree of quenching correlating with binding affinity and the amount of template bound to the polymer.

Characterization of the selectivity of a phenytoin imprinted polymer

The selectivity of analytical methods based on molecularly imprinted polymers (MIPs) is due to the preferential adsorption of the analyte(s) as compared to other substances (interferences). This paper shows the theoretical and practical difficulties, which have to be considered and solved when real samples need to be analysed in a wide range of analyte and interferant concentrations. It is shown that the estimation of interference effects requires either many measurements or a realistic model of the adsorption equilibrium in mixed solutions of the analyte and the interferences. Examples are shown for positive (cooperative) interference effects, for better experimental design and interpretation of binary isotherm measurements and for establishing the chemical model of interference from selectivity measurements. The usual MIP model consisting of a cavity, which closely fits the shape of the template from all sides, appears unsuitable for this MIP, and it is replaced with a more realistic, more open model. The applicability of the results to using non-imprinted polymers as selective sorbents and to screening drug candidates is also shown.