Preparation and characterization of imprinted monolith with metal ion as pivot

Novel coordination imprinted polymer monolithic column applied to the solid-phase extraction of flumequine from fish samples

In this study, a coordination imprinted polymer (CIP) solid-phase extraction (SPE) method was developed to determine the residues of flumequine (FLU) in fish samples. Silanized graphene oxide-doped CIP (SGO-CIP) monolithic column was prepared using FLU-Zn²⁺ as template in the presence of SGO. The synthesis conditions of SGO-CIP column were optimized by the response surface methodology. Under the optimum conditions, this column showed high specificity to FLU, and the adsorption capacity reached 61.74 ng mg^-1. The enrichment factor of the monolithic column was over 40-fold. Various factors affecting the extraction efficiency of SGO-CIP column during SPE were tested to achieve optimal enrichment and to reduce non-specific adsorption. FLU in fish was detected by using a high-performance liquid chromatography-fluorescence detection system. The detection limit was as low as 0.32 ng g^-1 and the recovery was as high as 95.2%, with relative standard deviations of below 5.9%. This simple and sensitive method may be applicable to the determination of FLU residues in foods.

Synthesis of a molecularly imprinted polymer and its application in selective extraction of fenoprofen from wastewater

The presence of various classes of pharmaceutical drugs in different environmental compartments has been reported worldwide. In South Africa, the detection of pharmaceuticals especially the non-steroidal anti-inflammatory drugs is recent, and more studies are being done in order to fully understand their fate in the aquatic environment. With considerations for the need of better sample preparation techniques, this study synthesized a molecularly imprinted polymer for the selective extraction of a non-steroidal anti-inflammatory drug, fenoprofen in aqueous environmental samples. Batch adsorption studies showed that adsorption of fenoprofen onto the cavities of the polymer followed a Langmuir isotherm as well as a pseudo second order model implying formation of a monolayer on the surface through chemisorption. The polymer had a maximum adsorption capacity of 38.8 mg g^-1 and a Langmuir surface area of 1607 m² g^-1. The imprinted polymer was then used as the selective sorbent for solid phase extraction in the analysis of fenoprofen from wastewater followed by chromatographic determination. The analytical method gave a detection limit of 0.64 ng mL^-1 and recovery of 99.6%. The concentration of fenoprofen detected in influent and effluent samples from two wastewater treatment plants ranged from 24 to 58 ng mL^-1. The ability of the treatment plants to remove fenoprofen during wastewater processing based on the difference in concentrations in influent and effluent samples was found to be 41%. This work has shown that there is a possibility of release of fenoprofen from wastewater treatment plants into surface water sources.

Improved Enantioselectivity for Atenolol Employing Pivot Based Molecular Imprinting

In the last few decades, molecular imprinting technology went through a spectacular evolution becoming a well-established tool for the synthesis of highly selective biomimetic molecular recognition platforms. Nevertheless, there is still room for advancement in the molecular imprinting of highly polar chiral compounds. The aim of the present work was to investigate the favorable kosmotropic effect of a ternary complex involving a polar chiral template (eutomer of atenolol) and a functional monomer, bridged by a central metal ion through well-defined, spatially directional coordinate bonds. The efficiency of the chiral molecular recognition was systematically assessed on polymers obtained both by non-covalent and metal-mediated molecular imprinting. The influence on the chromatographic retention and enantioselectivity of different experimental variables (functional monomers, cross-linkers, chaotropic agents, metal ions, porogenic systems, etc.) were studied on both slurry packed and monolithic HPLC columns. Deliberate changes in the imprinting and rebinding (chromatographic) processes, along with additional thermodynamic studies shed light on the particularities of the molecular recognition mechanism. The best performing polymer in terms of enantioselectivity (α = 1.60) was achieved using 4-vinyl pyridine as functional monomer and secondary ligand for the Co(II)-mediated imprinting of S-atenolol in the presence of EDMA as cross-linker in a porogenic mixture of [BMIM][BF₄]:DMF:DMSO = 10:1:5, v/v/v.

Applications of molecularly imprinted polymers for solid-phase extraction of non-steroidal anti-inflammatory drugs and analgesics from environmental waters and biological samples

The occurrence of pharmaceuticals used as non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics in the aquatic environment is a threat to humans and aquatic species at large. The primary route of these pharmaceuticals to aquatic environment is through human waste such as urine and faeces. The application of molecularly imprinted polymers (MIPs) in the solid-phase extraction (SPE) of such pollutants from environmental and biological samples is important for the pre-concentration of compounds and selectivity of the analytical methods. To date, there are still limited commercial suppliers of MIPs. However, it is easy to synthesize such polymers via non-covalent imprinting approach using easily available and affordable reagents. Therefore, the applications of MIPs in the SPE of NSAIDs and analgesics from environmental and biological samples are reviewed. This is very important because despite the fact that review articles on applications of MIPs for organic compounds have been reported, very little has focussed on NSAIDs and analgesics which are the major studied pharmaceuticals in the environment and biological samples. The review also brings out important aspects of common reagents used including the template molecules during MIP synthesis. Application and future trends are also discussed. Gaps such as little use of environmental friendly reagents such as ionic liquids have been identified. Also, the lack of MIP applications to some compounds such as fenoprofen has been observed which is likely to be developed in the near future.

Preparation of metallic pivot-based imprinted monoliths with a hydrophilic macromonomer

The hydrophilic macromonomer oligo(ethyleneglycol) methyl ether methacrylate (OEG) was introduced into a metal ion-mediated MIP matrix to achieve good selectivity and less hydrophobic character.

Water-compatible molecularly imprinted polymers prepared using metal–organic gel as porogen

A novel water-compatible approach suitable for molecular imprinting was described by using metal–organic gel (MOG) as the porogenic solvent.

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 of imprinted monolithic column with high content of monomers in ionic liquid

A MIP monolith with good permeability was successfully achieved using a strategy involving a high content of monomers in a [BMIM][BF₄]-based green solvent.

Ion-imprinted polymers for environmental monitoring of inorganic pollutants: synthesis, characterization, and applications

Ion imprinting has become one of the fast-growing technologies that have gained a lot of attention recently especially in the area of materials science. One of them is called the ion-imprinted polymers (IIPs). The IIPs are synthesized on the principles of enzyme phenomenon whereby a polymer is altered by a polymerization that takes place in the presence of a template that will be later removed to create cavities that will recognize only the analyte of interest. This specific and selective affinity for the target species decreases the chances of competition with other different types of ions. The imprinting technique started with the discovery of the bulk polymerization method where by the monomer, initiator, crosslinker, and template are mixed together and allowed to polymerize, and then the resulting polymer is ground and sieved to get particles with sizes suitable for the polymer's application. The IIPs have got some attractive qualities for use in environmental applications which include their stability and inexpensiveness and have a wide range of synthesis options with each suiting a certain unique application. Apart from environmental work, IIPs have applications in many other areas such as in membranes, in drug delivery, and in biosensors as alternatives to antibodies just to mention a few. This review focuses on the synthesis, types of imprinting, characterization, and applications of IIPs.

Fabrication of a novel and simple microcystin-LR photoelectrochemical sensor with high sensitivity and selectivity

Microcystin-LR (MC-LR), an inert electrochemical species, is difficult to be detected by a simple and direct electrochemical method. In the present work, a novel photoelectrochemical sensor is developed on highly ordered and vertically aligned TiO(2) nanotubes (TiO(2) NTs) with convenient surface modification of molecularly imprinted polymer (MIP) (denoted as MIP@TiO(2) NTs) for highly sensitive and selective determination of MC-LR in solutions. Molecularly imprinted polypyrrole (PPy) of MC-LR is chosen as the recognition element. The designed MIP@TiO(2) NTs photoelectrochemical sensor presents excellent applicability in MC-LR determination, with linear range from 0.5 to 100 μg L(-1) and limit of detection of 0.1 μg L(-1). Moreover, the sensor exhibits outstanding selectivity while used in coexisting systems containing 2,4-dichorophenoxyacetic acid, atrazine, paraquat, or monosultap with high concentration, 100 times that of MC-LR. The sensor presents good photoelectric conversion efficiency and detection sensitivity, as well as broad linear detection range, mainly because of the high specific surface area and photoelectric activity of TiO(2) NTs and the π bond delocalized electron system of PPy that promotes the separation of electron-holes. The prominent selectivity is from the MIP by forming multiple hydrogen bonds between PPy and MC-LR. Mechanisms for photoelectrochemical analysis and selective recognition are also discussed.