Imprinted Polymer Beads Research Articles

Preparation and Utilization of a Highly Discriminative Absorbent Imprinted with Fetal Hemoglobin.

Development in hemoglobin-based oxygen carriers (HBOCs) that may be used as alternatives to donated blood requires an extensive supply of highly pure hemoglobin (Hb) preparations. Therefore, it is essential to fabricate inexpensive, stable and highly selective absorbents for Hb purification. Molecular imprinting is an attractive technology for preparing such materials for targeted molecular recognition and rapid separations. In this case study, we developed human fetal hemoglobin (HbF)-imprinted polymer beads through the fusion of surface imprinting and Pickering emulsion polymerization. HbF was firstly covalently coupled to silica nanoparticles through its surface-exposed amino groups. The particle-supported HbF molecules were subsequently employed as templates for the synthesis of molecularly imprinted polymers (MIPs) with high selectivity for Hb. After removing the silica support and HbF, the resulting MIPs underwent equilibrium and kinetic binding experiments with both adult Hb (HbA) and HbF. These surface-imprinted MIPs exhibited excellent selectivity for both HbA and HbF, facilitating the one-step isolation of recombinant Hb from crude biological samples. The saturation capacities of HbA and HbF were found to be 15.4 and 17.1 mg/g polymer, respectively. The present study opens new possibilities for designed resins for tailored protein purification, separation and analysis.

Simultaneous determination of zearalenone and alternariol mycotoxins in oil samples using mixed molecularly imprinted polymer beads

This work reports the optimization of a method using Molecularly Imprinted Polymers (MIPs) for the simultaneous determination of zearalenone and alternariol mycotoxins. The method was optimized using a chemometric approach where in the optimized conditions, the cartridges with a mixture (50:50, w/w) of both MIPs, were loaded with 30 mL of sample, washed with 2 mL of ACN/water (20/80, v/v) and eluted with 2.5 mL of trifluoroacetic acid/MeOH (3/97, v/v). The extracts were analyzed by HPLC coupled to a fluorescence detector (FLD). The optimized method has been applied and validated to the analysis of the mycotoxins in maize, sunflower and olive oils samples with a limit of detection of 5 and 2 µg kg−1, respectively. Recoveries were in the range of 94 % to 108 % (RSD < 6 %) for zearalenone and 92 % to 113 % (RSD < 5 %) for alternariol. The results were confirmed by HPLC-MS/MS.

Imprinted polymer beads featuring both predefined multiple-point interaction and accessible binding sites for precise recognition of 2′-deoxyadenosine

“Tailor-made” formation of complementary binding sites via lock-and-key molecular binding mechanism is critical for selective adsorption of target molecules in environmental and chemical engineering fields. However, the innovative design of molecularly imprinted polymers (MIPs) remains a challenging task. Here, photo-crosslinked functional polymer building blocks consisting of monomeric methacrylic acid (MAA), 1-(vinylbenzyl)thymidine (VBT) and post-crosslinked monomeric cinnamoyloxyethyl methacrylate (CEMA) were firstly synthesized. MIPs beads (PC-MIPs) were then prepared by emulsion droplet microreactor, and finally their precise recognition of 2'-deoxyadenosine (dA) was investigated by batch mode adsorption. The prepared PC-MIPs microspheres have a large number of voids on the surface with interconnected cavities inside, and the bubble-like framework inside may be caused by the full encapsulation of bubbles from the low boiling point isolated phase. Due to the high density of accessible imprinted sites and strong interaction with dA, the maximum monolayer adsorption capacity of PC-MIPs was calculated to be 134.5 μmol g−1 for dA, surpassing most of the reported dA-imprinted sorbents. In addition, unique advantages of the post-crosslinking strategy combined with the emulsion template method exhibited good selectivity (imprinting factor higher than 2.71) and high stability, as well as excellent recyclability toward dA. Moreover, 82.4 % of dA was extracted by PC-MIPs from spiked human urine samples. Therefore, our work demonstrated an alternate strategy to design polymers bearing precise molecular recognition capability, and provided a new perspective for dA enrichment from biological samples.

Imprinted Polymer Beads Featuring Both Predefined Multiple-Point Interaction and Accessible Binding Sites for Precise Recognition of 2’-Deoxyadenosine

Imprinted Polymer Beads Featuring Both Predefined Multiple-Point Interaction and Accessible Binding Sites for Precise Recognition of 2’-Deoxyadenosine

Imprinted Polymer Beads Featuring Both Predefined Multiple-Point Interaction and Accessible Binding Sites for Precise Recognition of 2’-Deoxyadenosine

Imprinted Polymer Beads Featuring Both Predefined Multiple-Point Interaction and Accessible Binding Sites for Precise Recognition of 2’-Deoxyadenosine

Imprinted Polymer Beads Loaded with Silver Nanoparticles for Antibacterial Applications.

After the emergence of multidrug-resistant strains, antibiotic resistance in bacteria has become an important problem. Thus, materials for combating multidrug-resistant bacteria are of vital importance. In this work, we developed an antibacterial material that can selectively capture and destruct bacteria on the basis of their physical characteristics. To achieve bacterial capture and deactivation with a single material, we used bacterial cells as templates to synthesize surface-imprinted polymer beads in bacteria-stabilized Pickering emulsions. Acrylate-functionalized polyethylenimine was used to coat the bacterial surface so that the coated bacteria can act as a particle stabilizer to establish an oil-in-water Pickering emulsion. Hydrophobic Ag nanoparticles were introduced into the oil phase composed of cross-linking monomers. Bacteria-imprinted beads (BIB) were obtained after the oil phase was polymerized. Bacterial binding experiments confirmed the importance of the imprinted sites for specific recognition with the target bacteria. The Ag nanoparticles embedded inside the polymer beads enhanced bacterial inactivation and reduced the leakage of heavy metal in aquatic environment. The combination of bacteria-imprinting with delivery of general-purpose antibacterial reagents offers a useful approach toward selective capture and destruction of bacteria.

Synthesizing molecularly imprinted polymer beads for the purification of vitamin E

Molecularly imprinted polymer (MIP) beads imprinted with vitamin E (VE) were synthesized via a two-step swelling polymerization method, using methacrylic acid (MAA) and other functional monomers together with polystyrene (PS) microspheres as the substrate. In initial trials, different functional monomers were assessed, along with a variety of solvents and imprinting ratios. The MIPMAA sample exhibited the highest performance and was characterized and also assessed with regard to VE adsorption under various experimental conditions. This material exhibited reasonably good sphericity, porosity and stability, along with an excellent adsorption capacity of 46mg/g. This was much higher than the value for the corresponding non-imprinted polymer made with the same monomer, and 20% higher than that for an acrylamide-based MIP synthesized using a precipitation polymerization method. The core-shell structured MIPMAA also demonstrated fast adsorption kinetics, a low pressure drop and good reusability in fixed bed experiments. The VE adsorption equilibrium, selectivity, kinetics, thermodynamics and regeneration capacity of this material were also examined and are reported herein.

Integrating molecularly imprinted polymer beads in graphite-epoxy electrodes for the voltammetric biosensing of histamine in wines

This manuscript presents a voltammetric biosensing study with use of molecularly imprinted polymers to detect histamine in wine. Polymer beads were synthesized by standard precipitation polymerization method and implemented on the electrode surface via sol-gel immobilization. Scanning and confocal microscopy examinations permitted characterizing the material. Adsorptive stripping voltammetry in differential mode was the technique chosen for final application, selecting an enrichment time of 5 min. These conditions permitted a limit of detection of 0.19 μg mL−1 (1.0 μM), with a linear response range from 0.5 to 6.0 μg mL−1 (2.71–32.4 μM). The repeatability of the measurements was 4.6% relative standard deviation (n = 12). Principal component analysis showed the ability of the prepared receptor for discriminating other biogenic amines and potential interfering species. A final application, illustrating the determination of histamine, was completed to show agreement of results between the fluorimetric reference method and the proposed electrochemical approach.

Development of surface imprinted nanospheres using the inverse suspension polymerization method for electrochemical ultra sensing of dacarbazine

A new ultra sensing molecularly imprinted polymer beads modified pencil graphite electrode was fabricated, with the help of the inverse suspension polymerization technique, for ascertaining the adequate supplementation of dacarbazine in the cancer treatment. The inverse suspension polymerization technique was beneficial in obtaining surface imprinted polymer-based electrocatalytic nanospheres with narrow size distribution. These nanospheres were found to be superior to the corresponding microspheres and planar films, in terms of electrode kinetics and sensitivity, with the differential pulse anodic stripping voltammetric transduction. Herein, multiwalled carbon nanotubes functionalized ester links were invoked in between the imprinted nanospheres and the pencil graphite electrode surface to secure a stable coating and better electrodics. The proposed electrochemical sensor showed the imprinting factor and the analyte adsorption coefficient as high as 24.3 and 1.06 × 109 L mol−1, respectively. Furthermore, 16-fold and 4-fold faster electron transfer kinetics were observed with the imprinted nanospheres than the corresponding imprinted planar film and the microspheres based electrodes, respectively. The limits of detection [0.02 (aqueous), 0.02 (plasma), 0.01 (urine), and 0.03 ng mL−1 (pharmaceutics), (3σ, RSD ≤ 0.23%)] of dacarbazine, realized with the imprinted polymer nanospheres, were free from any cross-reactivity and false-positive complications in aqueous, blood plasma, urine, and pharmaceutical samples.

Preparation of diclofenac-imprinted polymer beads for selective molecular separation in water.

Molecular imprinting technique is an attractive strategy to prepare materials for target recognition and rapid separation. In this work, a new type of diclofenac (DFC)-imprinted polymer beads was synthesized by Pickering emulsion polymerization using 2-(dimethylamino)ethyl methacrylate as the functional monomer. The selectivity and capacity of the molecularly imprinted polymers (MIPs) were investigated in aqueous solution. Equilibrium binding results show that the MIPs have a high selectivity to bind DFC in a wide range of pH values. Moreover, in liquid chromatography experiment, the imprinted polymer beads were packed into column to investigate the binding selectivity under nonequilibrium conditions. The retention time of DFC on the MIP column is significantly longer than its structural analogues. Also, retention of DFC on the MIP column was significantly longer than on the nonimprinted polymer column under aqueous condition. As the new MIP beads can be used to achieve direct separation of DFC from water, the synthetic method and the affinity beads developed in this work opened new possibilities for removing toxic chemicals from environmental and drinking water.

Development of water compatible imprinted polymer beads for piezoelectric sensing of ultra-trace 5,6-dihydrouracil in biological fluids

In this work, a novel water compatible molecularly imprinted polymer was synthesized in bead shape by the precipitation polymerization technique. Immobilization of such imprinted beads on the surface of quartz crystal microbalance (QCM) was made through Au-S links using the “surface-grafting to” approach. The imprinted beads revealed a superiority in terms of recapture ability of analyte in the large concentration range and sensitivity as compared to traditionally imprinted monolith films. The piezoelectric analysis of target analyte (5,6-dihydrouracil) with imprinted polymer beads was found to be highly selective and sensitive, without any cross-reactivity and false-positives, in real samples. A perfect linearity between the frequency shift and the analyte concentration was observed in the range 0.03–1.75μM, with detection limits varying between 0.003–0.006μM (S/N=3) [cf., imprinted film modified QCM: 0.04–1.32μM, limit of detection 0.01μM (S/N=3)]. The endogenous 5,6-dihydrouracil level was also obtained in the blood plasma sample which may help exploring concerned dihydropyrimidine dehydrogenase activity, on the basis of concentration ratio [dihydrouracil]/[uracil] in cancer patients undergoing chemotherapy with 5-fluorouracil supplementation.

Molecularly imprinted PVC beads for the recognition of proteins

ABSTRACTUltrathin films of molecularly imprinted polymer (MIP) were prepared by photoiniferter on PVC beads for the selective uptake of lysozyme, taken as a model protein. Acrylamide was selected as the functional monomer and N,N‐methylenebisacrylamide as the crosslinking agent. The copolymerization process was confined to the surface of the PVC beads grafted with diethyldithiocarbamate iniferter initiator in the presence of lysozyme. After extraction of lysozyme from the shell of the PVC‐MIP beads, the latter were then used as artificial receptors for the rebinding of lysozyme. The sequential steps of the modification of PVC beads were monitored by XPS, infrared and Raman spectroscopies. The imprinting step was found to be essential as the PVC‐MIP beads could recognize lysozyme but not the non‐imprinted beads (PVC‐NIP). The binding properties of PVC‐MIP beads were determined using UV spectroscopy from adsorption isotherms of lysozyme, cytochrome, and myoglobin. The imprinted beads were found to be highly selective toward lysozyme over the competitive proteins. This work shows the interest of photoiniferter as an efficient mean for the design of molecularly imprinted polymer beads for rapid, selective removal of proteins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43694.

ChemInform Abstract: Precipitation Polymerization: A Versatile Tool for Preparing Molecularly Imprinted Polymer Beads for Chromatography Applications

AbstractReview: 116 refs.

Precipitation polymerization: a versatile tool for preparing molecularly imprinted polymer beads for chromatography applications

Minireview on recent advances of application of MIPs prepared by precipitation polymerization for recognition of target analytes in complex matrices.

Tailoring molecularly imprinted polymer beads for alternariol recognition and analysis by a screening with mycotoxin surrogates

Molecularly imprinted porous polymer microspheres have been prepared for selective binding of alternariol (AOH), a phenolic mycotoxin produced by Alternaria fungi. In order to lead the synthesis of recognition materials, four original AOH surrogates have been designed, prepared and characterized. They bear different number of phenol groups in various positions and different degree of O-methylation on the dibenzo[b,d]pyran-6-one skeleton. A comprehensive library of mixtures of basic, acidic or neutral monomers, with divinylbenzene or ethyleneglycol dimethacrylate as cross-linkers, were polymerized at a small scale in the presence of the four molecular mimics of the toxin molecule. This polymer screening has allowed selection of the optimal composition of the microbeads (N-(2-aminoethyl)methacrylamide, EAMA, and ethylene glycol dimethacrylate). The latter are able to bind AOH in water–acetonitrile (80:20, v/v) with an affinity constant of 109±10mM−1 and a total number of binding sites of 35±2μmolg−1, being alternariol monomethylether the only competitor species. Moreover, 1H NMR titrations have unveiled a 1:2 surrogate-to-EAMA stoichiometry, the exact interaction sites and a binding constant of 1.5×104M−2. A molecularly imprinted solid phase extraction (MISPE) method has been optimized for selective isolation of the mycotoxin from aqueous samples upon a discriminating wash with 3mL of acetonitrile/water (20:80, v/v) followed by determination by HPLC with fluorescence detection. The method has been applied, in combination to ultrasound-assisted extraction, to the analysis of AOH in tomato samples fortified with the mycotoxin at five concentration levels (33–110μgkg−1), with recoveries in the range of 81–103% (RSD n=6). To the best of our knowledge, this is the first imprinted material capable of molecularly recognizing this widespread food contaminant.

Molecularly imprinted polymer beads for clean-up and preconcentration of β-lactamase-resistant penicillins in milk.

This work describes the development and application of class-selective molecularly imprinted polymers (MIPs) for the analysis of beta-lactamase-resistant penicillins, namely cloxacillin (CLOXA), oxacillin (OXA), and dicloxacillin (DICLOXA), in milk samples. Our method is based on molecularly imprinted solid-phase extraction (MISPE) coupled to high-performance liquid chromatography (HPLC) with diode-array detection (DAD). 2-Biphenylylpenicillin (2BPEN), a surrogate with a close resemblance to beta-lactamase-resistant penicillins in terms of size, shape, hydrophobicity, and functionality, was synthesized and used as the template for the polymer synthesis. A MIP library was prepared and screened to select the optimum functional monomer, N-(2-aminoethyl)methacrylamide, and cross-linker, trimethylolpropane trimethacrylate, that provided the best recognition for the target antibiotics. For the MISPE application, the MIPs were prepared in the form of microspheres, using porous silica beads (40-75μm) as sacrificial scaffolds. The developed MISPE method enables efficient extraction from aqueous samples and analysis of the antimicrobials, when followed by a selective washing with 2mL acetonitrile-water (20:80 v/v) and elution with 1mL 0.05molL(-1) tetrabutylammonium in methanol. The analytical method was validated according to EU guideline 2002/657/EC. The limits of quantification (S/N = 10) were in the 5.3-6.3μgkg(-1) range, well below the maximum residue limits (MRLs) currently established. Inter-day mean recoveries were in the range 99-102% with RSDs below 9%, improving on the performance of previously reported MISPE methods for the analysis of CLOXA, OXA, or DICLOXA in milk samples.

Implementation of molecularly imprinted polymer beads for surface enhanced Raman detection.

Molecularly imprinted polymers (MIPs) have a predesigned molecular recognition capability that can be used to build robust chemical sensors. MIP-based chemical sensors allow label-free detection and are particularly interesting due to their simple operation. In this work we report the use of thiol-terminated MIP microspheres to construct surfaces for detection of a model organic analyte, nicotine, by surface enhanced Raman scattering (SERS). The nicotine-imprinted microspheres are synthesized by RAFT precipitation polymerization and converted into thiol-terminated microspheres through aminolysis. The thiol groups on the MIP surface allow the microspheres to be immobilized on a gold-coated substrate. Three different strategies are investigated to achieve surface enhanced Raman scattering in the vicinity of the imprinted sites: (1) direct sputtering of gold nanoparticles, (2) immobilization of gold colloids through the MIP's thiol groups, and (3) trapping of the MIP microspheres in a patterned SERS substrate. For the first time we show that large MIP microspheres can be turned into selective SERS surfaces through the three different approaches of assembly. The MIP-based sensing surfaces are used to detect nicotine to demonstrate the proof of concept. As synthesis and surface functionalization of MIP microspheres and nanoparticles are well established, the methods reported in this work are handy and efficient for constructing label-free chemical sensors, in particular for those based on SERS detection.

Magnetic Molecularly Imprinted Polymer Beads Obtained by Suspension Polymerization for the Adsorption of 2,4,6-Trichlorophenol from an Aqueous Solution in a Fixed-Bed Column

Highly effective magnetic molecularly imprinted polymer (MMIP) beads for adsorption of 2,4,6-trichlorophenol (2,4,6-TCP) were synthesized by suspension polymerization. The effect of various parameters such as bed depths (0.6, 1.1 and 1.7 cm), flow rate (1, 2 and 3 ml minute–1), influent 2,4,6-TCP concentrations (50, 100 and 200 mg l–1), influent solution pH (4, 6 and 8) and temperature (288, 298 and 308 K) was investigated. The breakthrough time increased with the increase of the bed depth, but decreased with an increase of the initial concentration, flow rate and temperature. The Adams–Bohart and Thomas models were applied to the adsorption process under experimental conditions to predict the breakthrough curves for process design. The Thomas model was in good agreement with the experimental data. Compared with magnetic non-imprinted polymers, MMIPs exhibited an excellent selectivity towards 2,4,6-TCP.

Preparation of magnetic molecularly imprinted polymer beads and their recognition for baicalein

Fe3O4–β-CD@MIPs were synthesized by UAPP using MAA as a functional monomer and EGDMA as a crosslinker in the presence of Fe3O4–β-CD nanoparticles as the template and baicalein (BAI) as the imprinting molecule.

Preparation of protein imprinted polymer beads by Pickering emulsion polymerization.

We present a new method for preparation of protein-specific polymer beads based on surface molecular imprinting in Pickering emulsion. In the first step, adult human hemoglobin (Hb) was adsorbed on silica nanoparticles. The protein-coated silica particles were then used to stabilize an oil-in-water emulsion (Pickering emulsion) composed of cross-linking monomer in the oil phase. After free radical polymerization of the oil phase, the protein-silica particles were removed to leave Hb-imprinted sites on the polymer surface. The protein-imprinted polymer microspheres were characterized by scanning electron microscopy and their selectivity was investigated by protein binding analysis. The new synthetic method based on Pickering emulsion polymerization produced easily accessible Hb binding sites on the surface of spherical polymer particles, which are useful for protein separation, purification and analysis.