An inverse opal photonic crystal sensor that could specifically detect chloramphenicol (CAP) in a label-free way was introduced in the current research. A colloidal crystal template was first prepared from monodisperse SiO(2) nanospheres. Precursors with different compositions were infused into the void spaces of the respective templates and aggregated. The template and the imprinted CAP were removed, and a molecularly imprinted photonic polymer (MIPP) with numerous nanocavities derived from the SiO(2) template was prepared. The MIPP could specifically recognize the target CAP. The results showed that the embedding and transporting of CAP could change the reflection peak intensity of the MIPP. The MIPP exhibited good responsiveness, with a detection range from 1 ng mL(-1) to 1 μg mL(-1) of CAP. The MIPP response time was 8 min upon its addition to CAP at a concentration of 10 ng mL(-1), which is shorter than that of other methods. After repeated use, the MIPP maintained a good performance and detection capacity. Thus, the results prove that the novel sensor could specifically detect CAP in a simple, time-saving, and low-cost manner. 相似文献
Based on the combination of colloidal‐crystal templating and a molecular imprinting technique, a sensor platform for efficient detection of atrazine in aqueous solution has been developed. The sensor is characterized by a 3D‐ordered interconnected macroporous structure in which numerous nanocavities derived from atrazine imprinting are distributed in the thin wall of the formed inverse polymer opal. Owing to the special hierarchical porous structure, the molecularly imprinted polymer opals (or molecularly imprinted photonic polymer; MIPP) allow rapid and ultrasensitive detection of the target analyte. The interconnected macropores are favorable for the rapid transport of atrazine in polymer films, whereas the inherent high affinity of nanocavites distributed in thin polymer walls allows MIPP to recognize atrazine with high specificity. More importantly, the atrazine recognition events of the created nanocavities can be directly transferred (label‐free) into a readable optical signal through a change in Bragg diffraction of the ordered macropores array of MIPP and thereby induce color changes that can be detected by the naked eye. With this novel sensory system, direct, ultrasensitive (as low as 10?8 ng mL?1), rapid (less than 30 s) and selective detection of atrazine with a broad concentration range varying from 10?16 M to 10?6 M in aqueous media is achieved without the use of label techniques and expensive instruments. 相似文献
A newly developed molecularly imprinted photonic polymer (MIPP) film, which was prepared by colloidal crystal templating and surface molecular imprinting, was used for selective capture of S-layer protein (SLP) from a complex Lactobacillus acidophilus sample. The colloidal crystal templates were formed by a dipping process followed by chemical binding of the imprinted template SLP molecules. A sandwich structure consisting of two glass slides was formed after the SLP–silica layer had been covered with a poly(methyl methacrylate) glass slide. After polymerization of the SLP–silica layer with the preprepared polymerization solution, hydrofluoric acid and acetic phosphate buffer solutions removed the silica particles and SLP molecules, respectively. The MIPP film obtained exhibited a three-dimensional, highly ordered and interconnected macroporous structure (pore size greater than 200 nm), which is specifically accessible to SLP molecules. The adsorbed SLP molecules were simply and straightforwardly detected by a fiber-optic spectrometer. The redshift of the Bragg diffraction peak of the MIPP film was linearly related to the number of SLP molecules that had been harvested in the film. The detection limit of the SLP–MMIP–fiber-optic spectrometer method for SLP was 1 ng mL-1. The MIPP sensor was successfully applied to detect SLP molecules in a crudely extracted Lactobacillus acidophilus sample. Our results prove the applicability of the SLP–MIPP film for fast and real-time measurement of SLP.
To convert the binding events on molecularly imprinted polymers (MIPs) into physically detectable signals and to extract the templates completely are the great challenges in developing MIP-based sensors. In this paper, a core-shell nanostructure was employed in constructing the MIP chemosensor for the improvements of template extraction efficiency and imprinted sites accessibility. Vinyl-substituted zinc(II) protoporphyrin (ZnPP) was used as both fluorescent reporter and functional monomer to synthesize atrazine-imprinted polymer shell at silica nanoparticle cores. The template atrazine coordinates with the Lewis acid binding site Zn of ZnPP to form a complex for the molecular imprinting polymerization. These imprinted sites are located in polymer matrix of the thin shells (~8 nm), possessing better accessibility and lower mass-transfer resistance for the target molecules. The fluorescence properties of ZnPP around the imprinted sites will vary upon rebinding of atrazine to these imprinted sites, realizing the conversion of rebinding events into detectable signals by monitoring fluorescence spectra. This MIP probe showed a limit of detection (LOD) of about 1.8 μM for atrazine detection. The core-shell nanostructured MIP method not only improves the sensitivity, but also shows high selectivity for atrazine detection when compared with the non-molecular imprinted counterparts. 相似文献
A novel solid phase extraction (SPE) method for determination of tetracyclines (TCs) in milk and honey samples by molecularly imprinted monolithic column was developed. Using tetracycline (TC) as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, methanol as the solvent, cyclohexanol and dodecanol as the mixed porogenic solvents, a TC imprinted monolithic column was prepared by in situ molecular imprinting technique for the first time, and the optimal synthesis conditions and the selectivity of TC imprinted monolithic column were investigated. The interfering substances in food samples and TCs can be separated successfully on imprinted column. Molecularly imprinted solid phase extraction (MISPE) coupling with C18 column was used to determinate the TCs in milk and honey. The recoveries of this method for six tetracyclines antibiotics such as tetracycline (TC), oxytetracycline (OTC), minocycline (MINO), chlortetracycline (CTC), metacycline (MTC) and doxycycline (DTC) were investigated, and high recoveries of 73.3-90.6% from milk samples and 62.6-82.3% from honey samples were obtained. A method for determination of TCs at low concentration level in milk and honey samples was successfully developed by using the monolithic column as the precolumn for solid phase extraction of six TCs compounds. 相似文献
Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO2 colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer–Emmett–Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid‐phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate. 相似文献
A multitemplate molecularly imprinted polymer was synthesized using fragments similar to gonyautoxins 1 and 4 including 2,4,6-triaminopyrimidine, 4-hydroxy-2-butanone, and imidazole as dummy templates by bulk polymerization. Scanning electron microscopy and infrared spectroscopy showed a porous structure and the formation of organic groups in the imprinting process of the polymer. One millilitre of 0.1?mol?L?1 acetic acid and 1?mL of 95% methanol were the optimized washing and eluting solutions during the molecularly imprinted solid-phase extraction. The adsorption capacity of the multitemplate molecularly imprinted polymer was lower than for the monotemplate molecularly imprinted polymer prepared in a previous study in seawater in which Alexandrium tamarense and Alexandrium minutum were cultivated. This result may due to the inappropriate combination of the dummy template fragments in the synthesis resulting in the unfitness of the imprinting sites for gonyautoxins 1 and 4. In general, it is inappropriate to use fragments with the similar parts to the analyte as the dummy templates. However, this work indicated the optimal molecularly imprinted polymer for the selective extraction of gonyautoxins 1 and 4. 相似文献
A highly selective sample cleanup procedure combined with molecularly imprinted SPE was developed for the isolation of crystal violet from seawater and seafood samples. The molecularly imprinted polymer was prepared using crystal violet as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. The crystal violet‐imprinted polymer was used as the selective sorbent for the SPE of crystal violet. An off‐line molecularly imprinted SPE method followed by HPLC with diode‐array detection for the analysis of crystal violet was also established. Good linearity on the molecularly imprinted SPE columns was obtained from 0 to 200 μg/L (R2 > 0.99). The result demonstrated that the proposed method can be used for the direct determination of crystal violet in seawater and seafood samples. Finally, five samples were analyzed and the following crystal violet concentrations were obtained: 0.92 and 0.52 μg/L in two seawater samples, as well as 0.36 and 0.27 μg/kg in two seafood samples. There is no crystal violet detected in the third seawater sample. 相似文献
A simple, sensitive, and selective molecularly imprinted solid‐phase extraction and spectrophotometric method has been developed for the clean‐up and preconcentration of indapamide from human urine. Molecularly imprinted polymers were prepared by a non‐covalent imprinting approach using indapamide as a template molecule, 2‐(trifluoromethyl) acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, N,N‐azobisisobutyronitrile as a thermal initiator and acetonitrile as a porogenic solvent. A non‐imprinted polymer was also prepared in the same way, but in the absence of template. Molecularly imprinted polymer and non‐imprinted polymer sorbents were dry‐packed into solid‐phase extraction cartridges. Eluates from cartridges were analyzed using a spectrophotometer for the determination of indapamide by referring to the calibration curve in the range 0.14–1.50 μg/mL. Preconcentration factor, limit of detection, and limit of quantification were 16.30, 0.025 μg/mL, and 0.075 μg/mL, respectively. A relatively high imprinting factor (9.3) was also achieved and recovery values for the indapamide spiked into human urine were in the range of 80.1–81.2%. In addition, relatively low within‐day (0.17–0.42%) and between‐day (1.1–1.4%) precision values were obtained as well. The proposed molecularly imprinted solid‐phase extraction and spectrophotometric method was successfully applied to selective extraction, preconcentration, and determination of indapamide from human urine samples. 相似文献
We have devised a facile and general methodology for the synthesis of various molecularly imprinted shells at the surface of polystyrene (PS) colloidal spheres to recognize the explosive compound 2,4,6-trinitrotoluene (TNT). PS spheres with surface-functionalized carboxyl-group layers could direct a selective imprinting polymerization on their surface through the hydrogen-bonding interactions between surface carboxyl groups and amino monomers. Meanwhile, homogeneous polymerization in the solution phase was completely prevented by stepwise polymerization. The overall process led to the formation of monodisperse molecularly imprinted core-shell microspheres, and was very successful in the preparation of organic polymer and inorganic xerogel shells. Furthermore, greater capacity and faster binding kinetics towards target species were achieved, because surface-imprinted sites ensured the complete removal of templates, good accessibility to target molecules, and low mass-transfer resistance. The results reported herein, concerning the production of high-quality molecularly imprinted products, could also form the basis for the formulation of a new strategy for the fabrication of various functional coating layers on colloidal spheres with potential applications in the fields of separations and chemical sensing. 相似文献
A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 μM, as compared to 100 μM for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the enhanced chemical properties of using the experimentally determined optimal polymerization solvent overcome deformation of imprinted binding sites by water swelling and benefits of using the polymerization solvent for rebinding of the template. 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
In the present work, the development of imprinted polymers selective towards mycophenolic acid and their application in food analysis are reported for the first time. To synthesize the molecularly imprinted polymer (MIP) 4-vinylpyridine and ethyleneglycol dimethacrylate were applied as functional monomer and cross-linker, respectively. Besides the toxin itself, the implementation of structural analogues as templates was evaluated. A molecularly imprinted solid-phase extraction (MISPE) procedure was designed for the selective clean-up of maize extracts. Binding experiments and Scatchard analysis indicated the presence of specific binding sites in the imprinted polymers. The imprinting effect varied along with the selected template. The dissociation constant (K(D)) of the higher affinity binding sites ranged from 0.8 μmol/l to 15.6 μmol/l, while the K(D) of the lower affinity binding sites was in the range of 138.5-519.3 μmol/l. The performance of the MIPs throughout the clean-up of spiked maize sample extracts was evaluated and compared with the results obtained when applying a non-imprinted polymer. Depending on the polymers and the spiked concentration, recoveries after MISPE and non-imprinted solid-phase extraction varied respectively from 49% to 84% and from 28% to 31%. The imprinted polymers were superior regarding matrix effect, limit of detection (LOD) and limit of quantification (LOQ). LOD ranged from 0.17 μg/kg to 0.25 μg/kg and LOQ varied from 0.57 μg/kg to 0.82 μg/kg. Analysis of 15 maize samples by liquid chromatography tandem mass spectrometry revealed that the MIPs could be excellent sorbents for clean-up of contaminated food samples. 相似文献
A new 2D molecular imprinting technique based on nanotemplating and soft-lithography techniques is reported. This technique allows the creation of target-specific synthetic recognition sites on different substrates using a uniquely oriented and immobilized template and the attachment of a molecularly imprinted polymer on a substrate. The molecularly imprinted polymer was characterized by AFM, fluorescence microscopy, and ATR-FTIR. We evaluated the rebinding ability of the sites with theophylline (the target molecule). The selectivity of the molecularly imprinted polymer was determined for the theophylline-caffeine couple. The molecularly imprinted polymer exhibited selectivity for theophylline, as revealed by competitive rebinding experiments. Fluorescence microscopy experiments provided complementary proof of the selectivity of the molecularly imprinted polymer surfaces toward theophylline. These selective molecularly imprinted polymers have the potential for chemical sensor applications. Because of its 2D nature, this novel chemical sensor technology can be integrated with many existing high-sensitivity multichannel detection technologies. 相似文献
An automated system has been developed for the determination of trace tetracycline antibiotics (TCs) in egg samples, based on online molecularly imprinted solid-phase extraction (MISPE) coupling with high-performance liquid chromatography (HPLC). Oxytetracycline and chlortetracycline were chosen as mixed templates to synthesize highly selective molecularly imprinted polymers for online extraction. Under the optimal online MISPE-HPLC condition, 10 mL egg samples were injected into the MISPE column and then the matrix was washed out. By rotating the switching valve, TCs were transferred to the analytical column and then separated by HPLC. Because sample pretreatment and chromatographic separation were carried out simultaneously, the whole analytical time (18 min) was significantly shortened compared with conventional offline techniques. The detection limits ranged from 0.8 to 1.3 ng/g. The enhancement factors were in the range of 159-410. The spiked recoveries of TCs in real egg samples ranged from 91.6 to 107.6% and the relative standard deviations (RSDs) were not higher than 4.0%. 相似文献