Direct rapid synthesis of MIP beads in SPE cartridges

ZnS:Mn Quantum Dots Coated with a Silica Molecularly Imprinted Polymer for Trace Teflubenzuron Detection in Vegetable Samples

A novel nanocomposite fluorescent probe consisting of quantum dots and a silica molecularly imprinted polymer (MIPs-capped ZnS:Mn QDs) was synthesized and applied for the rapid detection of teflubenzuron (TBZ) based on the fluorescence quenching of a composite probe via TBZ. The fluorescence quenching efficiency of MIP@SiO2@ZnS:Mn QDs displayed a linear relationship over the concentration range of 0-26.24 μmol/L with a correlation coefficient of 0.9857 and the limit of detection was 2.4 μg/L. The selectivity test showed that the nanocomposite had good selectively rebind TBZ with higher imprinting factor of 3.06 compared with four structurally similar compounds. In addition, the probe was successfully applied to the detection of TBZ in vegetable samples with a recovery of 90.3~97.1% and with a relative standard deviation below 3.2%. This developed method has the advantages of simple preparation, fast response and low toxicity for trace TBZ detection.

Molecularly imprinted polymer-based optical immunosensors

Molecularly imprinted polymers (MIPs) are artificial antibodies for a target molecule. The review focuses mainly on mechanistic steps involved in forming MIPs and the role of co-monomers and porogen. In addition, the electronic transition between different energy levels is explained with the help of the Jablonski diagram. Diverse receptor and target molecules for anchoring artificial MIPs are discussed, accentuating the synergetic effects obtained. The binding efficiency, selectivity, and sensitivity of various optical sensors are discussed intensively. In addition to this, we focused on synthesis, physical forms, characterization techniques, and microorganism detection of imprinted polymers. A brief investigation on the use of MIPs in cancer diagnosis is also included, and attention is extended to the important challenges faced in using imprinted polymers.

Assessment of the binding performance of histamine-imprinted microspheres by frontal analysis capillary electrophoresis

Frontal analysis capillary electrophoresis was used to evaluate the binding performance of molecularly imprinted microspheres (MIM) toward its template histamine and analogs at pH 7, and compared to the high performance liquid chromatographic method. In both methods, batch binding was employed and the binding parameters were calculated from the measured concentration of unbound amine analytes and afforded comparable histamine equilibrium dissociation constants (K_d ∼ 0.4 mM). FACE was easily carried out at shorter binding equilibration time (i.e. 30 min) and without the need to separate the microspheres, circumventing laborious and, in the case of the system under study, inefficient sample filtration. It also allowed for competitive binding studies by virtue of its ability to distinctly separate intact microspheres and all tested amines which could not be resolved in HPLC. K_d 's for nonimprinted (control) microspheres (NIM) from FACE and HPLC were also comparable (∼ 0.6 mM) but at higher histamine concentrations, HPLC gave lower histamine binding. This discrepancy was attributed to inefficient filtration of the batch binding samples prior to HPLC analysis resulting in an over-estimation of the concentration of free histamine brought about by the presence of unfiltered histamine-bound microspheres.

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.

On the influence of crosslinker on template complexation in molecularly imprinted polymers: a computational study of prepolymerization mixture events with correlations to template-polymer recognition behavior and NMR spectroscopic studies

Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer–crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity.

Artificial receptors

Herein I will provide a brief overview of artificial receptors with emphasis on molecularly imprinted polymers (MIPs) and their applications. Alternative techniques to produce artificial receptors such as in silico designed and modelled polymers as well as different receptors designed using libraries of more or less natural composition will also be mentioned. Examples of these include aptamers and bio-nanocomposites. The physical presentation of the receptors is important and may depend on the application. Block polymerization of MIPs and grinding to particles of suitable size used to be the preferred technique, but today beaded materials can be produced in sizes down to nanobeads and also nanofibers can be used to increase available surface area and thereby capacity. For sensor applications it may be attractive to include the artificial receptors in surface coatings or in membrane structures. Different composite designs can be used to provide additional desirable properties. MIPs and other artificial receptors are gaining rapidly increasing attention in very shifting application areas and an attempt to provide a systematic account for current applications has been made with examples from separation, solid-phase extraction, analysis, carbohydrate specific experiments, and MIPs-directed synthesis.

Monodispersed, molecularly imprinted polymers as affinity-based chromatography media

This review article deals with preparation methods for spherical and monodispersed molecularly imprinted polymers (MIPs) in micrometer sizes. Those methods include suspension polymerization in water, liquid perfluorocarbon and mineral oil, seed polymerization and dispersion/precipitation polymerization. The other methods are the use of beaded materials such as a spherical silica or organic polymer for grafting MIP phases onto the surfaces of porous materials or filling the pores of silica with MIPs followed by dissolution of the silica. Furthermore, applications of MIP microspheres as affinity-based chromatography media, HPLC stationary phases and solid-phase extraction media, will be discussed for pharmaceutical, biomedical and environmental analysis.

Investigating the mechanisms of 17β-estradiol imprinting by computational prediction and spectroscopic analysis

Molecular dynamics simulations combined with spectroscopic analysis were applied to understand the nature of recognition in molecularly imprinted polymers (MIPs), and for optimizing the MIP formulation. The best monomers for synthesizing imprinted materials for 17beta-estradiol (BE2) were selected by evaluating the strength of the template-monomer interaction derived from molecular dynamics simulations. A number of potential functional monomers for BE2 were screened for hydrogen-bonding strength in order to analyze template-monomer interactions favorable for synthesizing noncovalent MIPs, with the simulations revealing that methacrylic acid, 2-(diethylamino)ethyl methacrylate, and methacrylamide provided the highest binding affinity to BE2. These theoretical predictions agree with previously reported results on batch rebinding studies using the corresponding functional monomers for synthesizing a series of MIPs. Molecular analysis such as (1)H NMR was used for experimentally confirming the prevalent template-monomer interactions derived from the modeling results. Molecular dynamics simulations indicating monomer dimerization in the prepolymerization solution correlated with the nature of the porogenic solvent, which was confirmed by NMR studies on hydrogen-bonding interactions of methacrylic acid in different solvents. Furthermore, batch rebinding studies revealed that the specific functionalities of the monomers essential to rebinding are retained after polymerization, which proves that the application of computational methods for modeling the prepolymerization solution provides useful information for optimizing real MIP systems.

Small organic molecular imprinted materials: their preparation and application

Molecular imprinting is a technique for preparing polymeric materials that are capable of recognizing and binding the desired molecular target with a high affinity and selectivity. The materials can be applied to a wide range of target molecules, even those for which no natural binder exists or whose antibodies are difficult to raise. The imprinting of small organic molecules (e.g., pharmaceuticals, pesticides, amino acids, steroids, and sugars) is now almost routine. In this review, we pay special attention to the synthesis and application of molecular imprinted polymer (MIPs) imprinted with small organic molecules, including herbicides, pesticides, and drugs. The advantages, applications, and recent developments in small organic molecular imprinted technology are highlighted.

Selective sample treatment using molecularly imprinted polymers

The molecularly imprinted polymers (MIPs) are synthetic polymers possessing specific cavities designed for a target molecule. By a mechanism of molecular recognition, the MIPs are used as selective sorbents for the solid-phase extraction of target analytes from complex matrices. MIPs are often called synthetic antibodies in comparison with immuno-based sorbents; they offer some advantages including easy, cheap and rapid preparation and high thermal and chemical stability. This review describes the use of MIPs in solid-phase extraction with emphasis on their synthesis, the various parameters affecting the selectivity of the extraction, their potential to selectively extract analytes from complex aqueous samples or organic extracts, their on-line coupling with LC and their potential in miniaturized devices.

Molecularly imprinted polymers for solid-phase extraction and solid-phase microextraction: Recent developments and future trends

Molecularly imprinted polymers (MIPs) are synthetic polymers having 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, during past years a huge amount of papers have been published dealing with the use of MIPs as sorbents in solid-phase extraction, namely molecularly imprinted solid-phase extraction (MISPE). Although the majority of these papers were restricted to describe the use of different templates for different applications, several attempts proposing new alternatives to minimize the inherent drawbacks of the preparation and use of MIPs (i.e. template bleeding, tedious synthesis procedure, etc.) have been reported. Thus, this paper does not pretend to be a collection of MISPE-related papers but to give an overview on the significant attempts carried out during recent years to improve the performance of MIPs in solid-phase extraction. In addition, the use of MIPs packed in high performance liquid chromatography (HPLC) columns for the direct injection of crude sample extracts and the preparation of imprinted fibres for solid-phase microextraction will be also discussed.

Solid phase extraction of food contaminants using molecular imprinted polymers

Food contamination from natural or anthropogenic sources poses severe risks to human health. It is now largely accepted that continuous exposure to low doses of toxic chemicals can be related to several chronic diseases, including some type of cancer and serious hormonal dysfunctions. Contemporary analytical methods have the sensitivity required for contamination detection and quantification, but direct application of these methods on food samples can be rarely performed. In fact, the matrix introduces severe disturbances, and analysis can be performed only after some clean-up and preconcentration steps. Current sample pre-treatment methods, mostly based on the solid phase extraction technique, are very fast and inexpensive but show a lack of selectivity, while methods based on immunoaffinity extraction are very selective but expensive and not suitable for harsh environments. Thus, inexpensive, rapid and selective clean-up methods, relaying on "intelligent" materials are needed. Recent years have seen a significant increase of the "molecularly imprinted solid phase extraction" (MISPE) technique in the food contaminant analysis. In fact, this technique seems to be particularly suitable for extractive applications where analyte selectivity in the presence of very complex and structured matrices represents the main problem. In this review, several applications of MISPE in food contamination analysis will be discussed, with particular emphasis on the extraction of pesticides, drugs residua, mycotoxins and environmental contaminants.

Capturing molecules with templated materials—Analysis and rational design of molecularly imprinted polymers

The creation of synthetic tailor-made receptors capable of recognizing desired molecular targets with high affinity and selectivity is a persistent long-term goal for researchers in the fields of chemical, biological, and pharmaceutical research. Compared to biomacromolecular receptors, these synthetic receptors promise simplified production and processing, less costs, and more robust receptor architectures. During recent decades, molecularly imprinted polymers (MIPs) are widely considered mimics of natural molecular receptors suitable for a diversity of applications ranging from biomimetic sensors, to separations and biocatalysis. A remaining challenge for the next generation of MIPs is the synthesis of deliberately designed and highly efficient receptor architectures suitable for recognizing biologically relevant molecules, for which natural receptors are either not prevalent, or difficult to isolate and utilize. Hence, this review discusses recent advances in synthetic receptor technology for biomolecules (e.g. drugs, amino acids, steroids, proteins, entire cells, etc.) via molecular imprinting techniques. Surface imprinting methods and epitope imprinting approaches have been introduced for protein recognition at imprinted surfaces. Imprinting techniques in aqueous solution or organic-water co-solvents have been introduced avoiding denaturation of biomolecules during MIP synthesis. In addition, improved bioreactivity of entire enzyme or active site mimics generated by molecular imprinting will be highlighted. Finally, the emerging importance of molecular modeling and molecular dynamics studies detailing the intermolecular interactions between the template species, the porogenic solvent molecules, and the involved monomer and cross-linker in the pre-polymerization solution will be addressed yielding a rational approach toward next-generation MIP technology.