Biomimetic sensors of molecularly-imprinted polymers for chlorpromazine determination

A molecularly imprinted polymer based chemiluminescence array sensor for one-step determination of phenothiazines and benzodiazepines in pig urine

The residues of phenothiazines and benzodiazepines in foods of animal origin are dangerous to consumers. For inspection of their abuses, this study for the first time reported on the use of a chemiluminescence array sensor for the simultaneous determination of four phenothiazines and five benzodiazepines in pig urine. Two molecularly imprinted polymers were coated in different wells of a conventional 96-well microtiter plate as the recognition reagents. After sample loading, the absorbed analytes were initiated directly by using an imidazole enhanced bis(2,4,6-trichlorophenyl)oxalate-hydrogen peroxide system to emit light. The assay process consisted of only one sample-loading step prior to data acquisition, so one test was finished within 10 min. The limits of detection for the nine drugs in the pig urine were in a range of 0.1 to 0.6 pg/mL, and the recoveries from the fortified blank urine samples were in a range of 80.3 to 95%. Furthermore, the sensor could be reused six times. Therefore, this sensor could be used as a simple, rapid, sensitive and reusable tool for routine screening for residues of phenothiazines and benzodiazepines in pig urine.

Mimicking new receptors based on molecular imprinting and their application to potentiometric assessment of 2,4-dichlorophenol as a food taint

Innovative host-tailored polymers were prepared, characterized and used as recognition elements in potentiometric transducers for the selective quantification of 2,4-dichlorophenol (DCP).The polymer beads were synthesized using DCP as a template molecule, acrylamide (AM),methacrylic acid (MAA) and ethyl methacrylate (EMA) as functional monomers and divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as cross-linkers. The sensors were fabricated by the inclusion of MIPs in plasticized polyvinyl chloride (PVC) matrix. Response characteristics of the proposed sensors revealed anionic slopes of -59.2, -49.7 and -80.6 mV/decade with detection limits of 5.6 × 10^-5,5.9 × 10^-5 and 13.2 × 10^-5 mol/L for MIP/AM/DVB, MIP/MAA/DVB and MIP/EMA/EGDMA membrane based sensors, respectively. Good selectivity was observed over common inorganic/organic anions. Validation of the assay method according to IUPAC recommendations was justified ensuring the synthesis of good reliable novel sensors for DCP determination. The method was successfully applied for routine analysis of food taint in fish and fish farms water samples.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Synthesis and evaluation of uniformly sized nalidixic acid-imprinted nanospheres based on precipitation polymerization method for analytical and biomedical applications

For the first time in this work, uniform molecularly imprinted polymer (MIP) nanoparticles were prepared using nalidixic acid as a template. The MIP nanoparticles were successfully synthesized by precipitation polymerization applying methacrylic acid (MAA) as a functional monomer and trimethylolpropane trimethacrylate (TRIM) as a cross-linking monomer at different mole ratios. The morphology, binding, recognition, selectivity, and in vitro release behaviors of obtained particles were studied. The produced polymers were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetric. Furthermore, their morphology was analyzed accurately by scanning electron microscopy, photon correlation spectroscopy, and Brunauer-Emmett-Teller analysis. The nanospheres and microspheres with mean diameter values of 94 nm, 256 nm, and 1.2 µm were obtained using nalidixic acid-MAA-TRIM various mole ratios. Among the MIPs, the product with nalidixic acid-MAA-TRIM mole ratio of 1:12:12 established nanospheres with the lowest polydispersity index (0.003), an average pore diameter (12 nm), and the highest specific surface area (280 m(2) g(-1)) and selectivity factor (10.4). Results from binding experiments demonstrated that the imprinted nanospheres with a 94-nm mean diameter and a binding capacity of 28 mg of nalidixic acid per gram of polymer had higher specific affinity to nalidixic acid in contrast with the other imprinted nanospheres, microspheres, and nonimprinted particles. However, the binding performance of imprinted nanospheres in human serum was estimated using high-performance liquid chromatography analysis (binding approximately 98% of nalidixic acid). In addition, release experiments proved to be successful in the controlled release of nalidixic acid during a long period. The 20% of loaded nalidixic acid was released from the imprinted nanospheres within the first 20 h, whereas the remaining 80% was released in the after 120 h. The nalidixic acid release kinetics from the MIPs was highly affected by properties of the particles.

Application of molecularly imprinted polymers in food analysis: clean-up and chromatographic improvements

Several natural and synthetic substances have been monitored in analytical laboratories worldwide to ensure food safety. Multiple residue detection (i.e., detection of multiple analytes in a single sample or matrix) is a main weakness of existing analytical methods, when fast and reliable results are required. Multianalyte approaches may save time and money in the food industry, and more importantly, they allow the quick release of food products into the marketplace. In addition, multianalyte approaches notably decrease the time required between sampling and analysis to meet legal requirements. However, to achieve analytical success, it is necessary to develop thorough clean-up procedures to extract analytes from the matrix. In addition, good chromatographic separation methods are also necessary to distinguish closely related analytes. Molecular imprinting technology (MIT) is an emerging, powerful tool for sample extraction and chromatography. First used for solid-phase extraction, molecularly imprinted polymers (MIPs) are also effective chromatographic phases for the separation of isomers and structurally related molecules. In recent years, a number of analytical methods utilising MIT have been applied for the analysis of residues in food, and existing methodologies have been improved. This review article describes the latest applications of MIT in the development of methodologies to monitor the presence of residues of veterinary products in foodstuff.

Molecularly imprinted photonic hydrogels as colorimetric sensors for rapid and label-free detection of vanillin

A novel colorimetric sensor for the rapid and label-free detection of vanillin, based on the combination of photonic crystal and molecular imprinting technique, was developed. The sensing platform of molecularly imprinted photonic hydrogel (MIPH) was prepared by a noncovalent and self-assembly approach using vanillin as a template molecule. Morphology characterization by scanning electron microscope (SEM) showed that the MIPH possessed a highly ordered three-dimensional (3D) macroporous structure with nanocavities. The vanillin recognition events of the created nonocavities could be directly transferred into readable optical signals through a change in Bragg diffraction of the ordered macropores array of MIPH. The Bragg diffraction peak shifted from 451 to 486 nm when the concentration of the vanillin was increased from 10⁻¹² to 10⁻³ mol L⁻¹ within 60 s, whereas there were no obvious peak shifts for methyl and ethyl vanillin, indicating that the MIPH had high selectivity and rapid response for vanillin. The adsorption results showed that the hierarchical porous structure and homogeneous layers were formed in the MIPH with higher adsorption capacity. The application of such a label-free sensor with high selectivity, high sensitivity, high stability, and easy operation might offer a potential method for rapid real-time detection of trace vanillin.