Six molecularly imprinted polymers (MIPs) of erythromycin (ERY) were prepared by noncovalent bulk polymerization using methacrylic
acid (MAA) as the functional monomer. On the basis of binding analysis, the MIPs with 1:2 optimum ratio of template to MAA
were selected for subsequent scanning electron microscopy and Brunauer–Emmett–Teller analyses, which indicated that the MIPs
had more convergent porous structures than the nonimprinted polymers. The equilibrium binding experiments showed that the
binding sites of MIPs were heterogeneous, with two dissociation constants of 0.005 and 0.63 mg mL−1, respectively. Furthermore, the performance of the MIPs as solid-phase extraction (SPE) sorbents was evaluated, and the selectivity
analysis showed that the MIPs could recognize ERY with moderate cross-reactivity for other macrolides. The overall investigation
of molecularly imprinted SPE for cleanup and enrichment of the ERY in pig muscle and tap water confirmed the feasibility of
utilizing the MIPs obtained as specific SPE sorbents for ERY extraction in real samples.
Figure Schematic diagram of the preparation and application of the erythromycin imprinted molecularly imprinted polymers
Suquan Song and Aibo Wu contributed equally to this work. 相似文献
A rapid, specific, and sensitive method has been developed using molecularly imprinted polymers (MIPs) as solid-phase extraction
sorbents for extraction of trace tetracycline antibiotics (TCs) in foodstuffs. MIPs were prepared by precipitation polymerization
using tetracycline as the template. Under the optimal condition, the imprinting factors for MIPs were 4.1 (oxytetracycline),
7.0 (tetracycline), 7.4 (chlortetracycline), 7.7 (doxycycline), respectively. Furthermore, the performance of MIPs as solid-phase
extraction sorbents was evaluated and high extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) procedure
was demonstrated. Compared with commercial sorbents, MISPE gave a better cleanup efficiency than C18 cartridge and a higher
recovery than Oasis HLB cartridge. Finally, the method of liquid chromatography–tandem mass spectrometry coupled with molecular-imprinted
solid-phase extraction was validated in real samples including lobster, duck, honey, and egg. The spiked recoveries of TCs
ranged from 94.51% to 103.0%. The limits of detection were in the range of 0.1–0.3 μg kg−1.
Chromatograms obtained by direct injection of the spiked egg extracts (5 × 10-3 mmol L−1) and purification with MISPE 相似文献
Molecularly imprinted polymers (MIPs) were prepared using bisphenol A (BPA) as a template by precipitation polymerization. The polymer that had the highest binding selectivity and ability was used as solid-phase extraction (SPE) sorbents for direct extraction of BPA from different biological and environmental samples (human serum, pig urine, tap water and shrimp). The extraction protocol was optimized and the optimum conditions were as follows: conditioning with 5 mL methanol–acetic acid (3:1), 5 mL methanol, 5 mL acetonitrile and 5 mL water, respectively, loading with 5 mL aqueous samples, washing with 1 mL acetonitrile, and eluting with 3 mL methanol. MIPs can selectively recognize, effectively trap and preconcentrate BPA over a concentration range of 2–20 μM. Recoveries ranged from 94.03 to 105.3 %, with a relative standard deviation lower than 7.9 %. Under the optimal condition, molecularly imprinted SPE recoveries of spiked human serum, pig urine, tap water and shrimp were 65.80, 82.32, 76.00 and 75.97 %, respectively, when aqueous samples were applied directly. Compared with C18 SPE, a better baseline, better high-performance liquid chromatography separation efficiency and higher recoveries were achieved after molecularly imprinted SPE.
相似文献
Organophosphorus insecticides are widely employed in agriculture, and residues of them can remain after harvesting or storage.
Pesticide residue control is an important task for ensuring food safety. Common chromatographic methods used in the determination
of pesticide residues in food require clean-up and concentration steps prior to quantitation. While solid-phase extraction
has been widely employed for this purpose, there is a need to improve selectivity. Due to their inherent biomimetic recognition
systems, molecularly imprinted polymers (MIP) allow selectivity to be enhanced while keeping the costs of analysis low. In
this work, a MIP that was designed to enable the selective extraction of fenitrothion (FNT) from tomatoes was synthesized
using a noncovalent imprinting approach. The polymer was prepared using methacrylic acid as functional monomer and ethyleneglycol
dimethacrylate as crosslinking monomer in dichloromethane (a porogenic solvent). The polymer was characterized by Fourier
transform infrared spectroscopy, solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and nitrogen
sorption porosimetry. The pore structure and the surface area were evaluated using the BET adsorption method. To characterize
the batch rebinding behavior of the MIP, the adsorption isotherm was measured, allowing the total number of binding sites,
the average binding affinity and the heterogeneity index to be established. A voltammetric method of quantifying FNT during
the molecularly imprinted solid-phase extraction (MISPE) studies was developed. The polymer was placed in extraction cartridges
which were then used to clean up and concentrate FNT in tomato samples prior to high-performance liquid chromatographic quantitation.
The material presented a medium extraction efficiency of 59% (for analyses performed with three different cartridges on three
days and a fortification level of 5.0 μg g−1) and selectivity when used in the preparation of tomato samples, and presented the advantage that the polymer could be reused
several times after regeneration.
Figure 相似文献
Cholesterol-imprinted polymers were prepared in bulk polymerization by the methods of covalent and non-covalent imprinting. The former involved the use of a template-containing monomer, cholesteryl (4-vinyl)phenyl carbonate, while the latter used the complexes of template and functional monomer, methacrylic acid or 4-vinylpyridine prior to polymerization. Columns packed with these molecularly imprinted polymers (MIPs) were all able to separate cholesterol from other steroids. For different combinations of cholesterol and beta-estradiol concentrations in a total of 1 g/l, the peak retention times for both compounds were nearly constant. The adsorption capacity for cholesterol onto the MIPs was found to significantly depend on the use of functional monomers, but the selectivity factors were only slightly different from each other at 2.9 to 3.2 since the separation was all based on the specific binding of cholesterol to recognition sites formed on the imprinted polymers. The capacity factors for cholesterol were determined to be 3.5, 4.0 and 3.1, respectively, for covalently imprinted, 4-vinylpyridine-based, and methacrylic acid-based non-covalently imprinted polymers. However, the covalently imprinted polymer was found to have a higher adsorption capacity for cholesterol and about fivefold higher chromatographic efficiency for cholesterol separation, in comparison with non-covalently imprinted polymers. The use of covalent imprinting significantly reduced the peak broadening and tailing. This advantage along with constant retention suggests that the covalently imprinted polymer has potential for quantitative analysis. 相似文献
Molecularly imprinted polymers (MIPs) are synthetic polymers with a predetermined selectivity for a given analyte, or group of structurally related compounds, that make them ideal materials to be used in separation processes. In this sense, it is not surprising that the first applications of MIPs were as tailor-made chiral stationary phases in liquid chromatography. However, peak broadening and tailing, especially of the more retained enantiomers, were observed. Accordingly, this paper gives an overview of the attempts carried out during the recent years to improve the chromatographic performance of MIPs in liquid chromatography and capillary electrophoresis as well as the more recent applications. We conclude that MIPs are very promising materials to be used as selective stationary phases in chromatography although further developments are necessary in order to fully exploit their potential. 相似文献
A highly selective molecularly imprinted polymer (MIP) for the recognition of the pesticide carbaryl in water has been synthesized
using halogenated bisphenol A compounds as one of the polymeric precursors and carbaryl as the template molecule. On the basis
of the heavy-atom effect, both the brominated and the iodinated MIPs allowed analyte detection by room-temperature-phosphorescence
measurements. In the presence of an oxygen scavenger (sodium sulphite) the halide, included in the polymeric structure, induced
efficient room-temperature phosphorescence of the analyte (once it had been selectively retained by the MIP). The MIP cavity
can be easily regenerated for subsequent sample injections with 2 mL methanol. The optosensing system developed has demonstrated
high selectivity for carbaryl, even in the presence of other luminophores that could be unspecifically adsorbed onto the MIP
surface. Under optimal experimental conditions, the detection limit for the target molecule was 4 μg/L (3-mL sample injection
volume), and the linear range extended up to 1 mg/L of the analyte. Good reproducibility was achieved (a relative standard
deviation of 3% was obtained for ten replicates of 150 μg/L carbaryl). The synthesized sensing material showed good stability
for at least 3 months after preparation. Finally, the applicability to carbaryl determination in real samples was evaluated
through the successful determination of the pesticide in spiked mineral and tap water samples.
Figure Schematic diagram of carbaryl recognition process by an halogenated molecularly imprinted polymer for room temperature phosphorescence
detection of the analyte. 相似文献
The replacement of antibodies by molecularly imprinted polymers (MIPs) has been investigated for many decades. However, indirect protocols (including natural primary and secondary antibodies) are still utilized to evaluate the ability of MIP thin films to recognize target molecules. MIPs can be prepared as either a thin film or as particles, and cavities that are complementary to the template can be generated on their surfaces. We have prepared thin film MIPs and particle MIPs prepared by solvent evaporation and phase inversion, respectively, from solutions of poly(ethylene-co-vinyl alcohol) (pEVAL) in the presence of the target analytes amylase, lysozyme, and lipase. These were first adsorbed on MIP thin films and by MIP particles that contain fluorescent quantum dots. Sandwich fluoroimmunoassays were then conducted to quantify them in MIP-coated 96-well microplates. The method was applied to determine amylase in saliva, and results were compared with a commercial analytical system.
Two series of molecularly imprinted polymers (MIPs) for the class-selective recognition of glucuronides have been prepared by using lipophilic substructures of the target analyte as template molecule and potent host monomers against oxyanions, that are expected to establish a strong stoichiometric interaction with the single carboxylic group of the template. The polymers were tested as stationary phases in liquid chromatography for specific recognition. A preliminary investigation of the imprinting properties of eleven MIPs was carried out, by comparing the retention time of the template and of structurally related compounds on the MIP column with that on the corresponding non-imprinted polymer (NIP). The two polymers showing the best performance were selected to further test cotinine, mycophenolic acid, testosterone and their respective glucuronides as model compounds. The high specificity obtained against glucuronides and the different chemical structure of the parent drug make the two MIPs class-selective imprinted receptors, also suitable for SPE application. 相似文献
A selective molecularly imprinted solid-phase extraction (MISPE) for indomethacin (IDM) from water samples was developed.
Using IDM as template molecule, acrylamide (AM) or methacrylic acid (MAA) as functional monomer, ethylene dimethacrylate (EDMA)
as crosslinker, and bulk or suspension polymerization as the synthetic method, three molecularly imprinted polymers (MIPs)
were synthesized and characterized with a rebinding experiment. It was found that the MIP of AM-EDMA produced by bulk polymerization
showed the highest binding capacity for IDM, and so it was chosen for subsequent experiments, such as those testing the selectivity
and recognition binding sites. Scatchard analysis revealed that at least two kinds of binding sites formed in the MIP, with
the dissociation constants of 7.8 μmol L−1 and 127.2 μmol L−1, respectively. Besides IDM, three structurally related compounds — acemetacin, oxaprozin and ibuprofen — were employed for
selectivity tests. It was observed that the MIP exhibited the highest selective rebinding to IDM. Accordingly, the MIP was
used as a solid-phase extraction sorbent for the extraction and enrichment of IDM in water samples. The extraction conditions
of the MISPE column for IDM were optimized to be: chloroform or water as loading solvent, chloroform with 20% acetonitrile
as washing solution, and methanol as eluting solvent. Water samples with or without spiking were extracted by the MISPE column
and analyzed by HPLC. No detectable IDM was observed in tap water and the content of IDM in a river water sample was found
to be 1.8 ng mL−1. The extraction efficiencies of the MISPE column for IDM in spiked tap and river water were acceptable (87.2% and 83.5%,
respectively), demonstrating the feasibility of the prepared MIP for IDM extraction.
Figure Molecularly imprinted polymer-based solid-phase extraction for indomethacin 相似文献
To extend the application of molecularly imprinted polymers, the dual‐templates molecularly imprinted monolithic columns were developed in a capillary format. Two templates serotonin and histamine were simultaneously imprinted using two different functional monomers such as methacrylic acid (MAA) and methylenesuccinic acid (MSA) in a mixture of ethylene glycol dimethacrylate (EDMA) as a cross‐linker and AIBN as polymerization initiator dissolved in DMF as porogen. The resulting molecular imprinted polymers (MIPs) were characterized based on their performance in the CEC separation of two imprinted templates. The optimization parameters such as pH, ACN composition, and concentration of the eluent were varied to achieve best resolution and efficiency for CEC separation of templates with each MIP column. It was found that the MIP monolith column fabricated using MSA offered better resolution and separation efficiency compared to column fabricated with MAA. This work utilized the dual‐templates imprinting approach successfully and broadens the scope of multi‐templates imprinting capabilities in capillary format in CEC application. 相似文献
Environmental analysis is a potential key application for chemical sensors owing to their inherent ability to detect analytes
on-line and in real time in distributed systems. Operating a chemosensor in a natural environment poses substantial challenges
in terms of ruggedness, long-term stability and calibration. This article highlights current trends of achieving both the
necessary selectivity and ruggedness: one way is deploying sensor arrays consisting of robust broadband sensors and extracting
information via chemometrics. If using only a single sensor is desired, molecularly imprinted polymers offer a straightforward
way for designing artificial recognition materials. Molecularly imprinted polymers can be utilized in real-life environments,
such as water and air, aiming at detecting analytes ranging from small molecules to entire cells.
Figure 相似文献
The work done during the past decade in order to adapt molecularly imprinted polymers (MIPs) to the capillary format and subsequently use these highly selective matrices for capillary electrochromatography (CEC) are reviewed in this article. MIPs are prepared utilizing a templated polymer synthesis where the template addresses the selectivity of the resulting polymer. These polymers possess binding characteristics that are comparable to the biological antibodies. Due to the polyclonality of the binding sites in the MIP, the separation result in severe peak broadening and tailing when performed in the isocratic mode. This was seen early in the development of MIPs as selective stationary phases in liquid chromatography (LC). As a mean of decreasing these problems, much effort was put into adapting the MIP to fit in CEC systems, that offers an efficiency that is superior to that in LC. Aiming to increase the efficiency of the MIP-CEC systems, different MIP formats have been developed that can be divided into three conceptually different categories, i.e., the monolithic, the microparticle and the coating. The strive for MIP formats that can be used in small bore capillaries has led to the development of MIP formats applicable to miniaturized systems approaching the chip format. Although prepared in order to perform MIP-CEC mediated separations, these formats can be used in a broad range of applications were the characteristics of the MIP, e.g. stability, selectivity and cost efficiency, could offer an interesting solution to cover the needs. 相似文献
Despite the increasing number of applications of molecularly imprinted polymers (MIP) in analytical chemistry, the synthesis
of polymers with hemin introduced as the catalytic center to mimic the active site of peroxidase remains as a challenge. In
the current work, a new type of molecularly imprinted polymer (MIP) was synthesized with 4-aminophenol (4-APh) as the template
and two monomers: hemin, which acts as the catalytic center, and methacrylic acid (MAA), which is used to build the active
sites. This work shows that MIP successfully mimics peroxidase. For this purpose, a flow injection analysis system coupled
to an amperometric detector was investigated through multivariate analysis. The determination of 4-APh was not affected by
the equimolar presence of structurally similar phenol compounds, including catechol, 4-chloro-3-methylphenol, 2-aminophenol,
guaiachol, chloroguaiachol and 2-cresol, thus highlighting the good performance of the imprinted polymer. Under the optimized
experimental conditions, an analytical curve covering a wide linear response range from 0.8 up to 500 μmol L−1 (r > 0.999) was obtained, and the method gave satisfactory precisions (n = 8), as evaluated via the relative standard deviation (RSD), of 4.1 and 3.2% for solutions of 4-APh of 50 and 500 μmol L−1, respectively. Recoveries of 96–111% from water samples (tap water and river water) spiked with 4-APh were achieved, thus
illustrating the accuracy of the proposed system.
Figure Schematic presentation of the synthesis of the MIP 相似文献
A β-estradiol receptor binding mimic was synthesised using molecular imprinting. Bulk polymers and spherical polymer nanoparticles
based on methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and crosslinker, respectively, were
prepared in acetonitrile. The selectivity was evaluated by radioligand binding assays. The imprinted polymers were very specific
to β-estradiol since the control polymers bound virtually none of the radioligand. The bulk polymer was then employed to screen
endocrine disrupting chemicals. Structurally related steroids like α-estradiol, estrone and ethynylestradiol showed, respectively,
14.0, 5.0 and 0.7% of relative binding to the β-estradiol polymer, whereas most unrelated chemicals did not bind at all. These
results are compared to those obtained with a bioassay using stably transfected yeast cells in culture bearing the human estrogen
receptor. The receptor was activated by several estrogen-like chemicals and to a lesser extent by some structurally related
chemicals.
Figure A molecularly imprinted polymer that was a synthetic receptor for beta-estradiol was used for the screening of endocrine disrupting
chemicals that are structurally related or unrelated to beta-estradiol. The results were compared with the recognition of
the compounds by the biological estrogen receptor expressed in yeast cells. Related steroids like alpha-estradiol, estrone
and ethynylestradiol showed significant binding to the beta-estradiol imprinted polymer, whereas most unrelated chemicals
did not bind. The biological receptor was activated by several estrogen-like chemicals, and to a lesser extent by some structurally
related chemicals 相似文献
Molecularly imprinted polymers (MIPs) are tailor-made synthetic polymers with a predetermined selectivity for a given analyte, or group of structurally related compounds, that make them ideal materials for use as stationary phases in affinity chromatography. However, extensive peak broadening and tailing, especially of the more retained compound (normally the template) are often observed. Thus, huge efforts have been made during recent years to use MIPs in capillary electrochromatography, which is inherently a more efficient chromatographic technique than conventional HPLC. Accordingly, this paper gives an overview of the attempts carried out in the recent past to improve the chromatographic performance of MIPs in capillary electrochromatography as well as more recent applications. It is concluded that MIPs are very promising materials for use as selective stationary phases in CEC. 相似文献
Highly sensitive flow-injection chemiluminescence (CL) combined with molecularly imprinted solid-phase extraction (MISPE)
has been used for determination of 2,4-dichlorophenol (2,4-DCP) in water samples. The molecularly imprinted polymer (MIP)
for 2,4-DCP was prepared by non-covalent molecular imprinting methods, using 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate
(EGDMA) as the monomer and cross-linker, respectively. 2,4-DCP could be selectively adsorbed by the MIP and the adsorbed 2,4-DCP
was determined by its enhancing effect on the weak chemiluminescence reaction between potassium permanganate and luminol.
The enhanced CL intensity was linear in the range from 1 × 10−7 to 2 × 10−5g mL−1. The LOD (S/N = 3) was 1.8 × 10−8g mL−1, and the relative standard deviation (RSD) was 3.0% (n = 11) for 1.4 × 10−6g mL−1. The proposed method had been successfully applied to the determination of 2,4-DCP in river water.
Figure Effect of 4-VP content on the ultraviolet spectrum of 2,4-DCP in chloroform 相似文献
The authors have prepared amino-functionalized carbon dots (AC-dots) and applied them to fluorescently label a molecularly imprinted polymer (MIP) prepared by using 2,4-dinitrotoluene (DNT) as a template. Since DNT can retard vinyl polymerization, poly(methyl acrylate-co-acrylic acid) was used as a monomer. Non-imprinted polymers (NIPs) were also synthesized in order to compare data. As expected, MIPs exhibit higher adsorption than NIPs, with imprinting efficiencies ranging from 2 to 2.5. DNT is specifically captured by the cavities in the MIP and interact with AC-dots on the surface, resulting in quenching of the fluorescence of the AC-dots. Response to DNT reaches equilibrium within ~30 min. The method has a dynamic range that extends from 1 to 15 ppm, and allows for quantitation of DNT in aqueous solutions, with a detection limit of 0.28 ppm. Selectivity tests conducted in presence of DNT analogs demonstrated the selective recognition of DNT.