Synthesis and theoretical study of molecularly imprinted monoliths for HPLC

Molecularly imprinted polymers in online extraction liquid chromatography methods: Current advances and recent applications

BACKGROUND

One of the primary objectives in green analytical practices is the seamless integration of extraction and separation steps, resulting in the augmentation of both analytical throughput and method performance. Consequently, the exploration of prospective sorbent materials has drawn significant attention in the scientific community, particularly concerning the potential for online procedures. Employing the optimal sorbent material within an automated analytical approach holds the promise of elevating the precision of the analytical evaluation. Molecularly imprinted polymers (MIPs) excel in specific analyte interaction within complex matrices. However, MIPs' full potential was not widely exploring especially for online analytical methodologies.

RESULTS

Here is presented a comprehensive overview of the current applications of MIPs as sorbent materials within integrated and automated separation methodologies applied to diverse matrices including biological, food, and environmental samples. Notably, their primary advantage, as evidenced in the literature, lies in their exceptional selectivity for the target analyte discussed according to the adopted synthesis protocol. Furthermore, the literature discussed here illustrates the versatility of MIPs in terms of modification with one or more phases which are so-called hybrid materials, such as molecularly imprinted monoliths (MIM), the molecularly imprinted ionic liquid polymer (IL-MIP), and restricted access to molecularly imprinted polymer (RAMIP). The reported advantages enhance their applicability in integrated and automated separation procedures, especially to the column switching methods, across a broader spectrum of applications.

SIGNIFICANCE

This revision aims to demonstrate the MIP's potential as a sorbent phase in integrated and automated methods, this comprehensive overview of MIP polymers in integrated and automated separation methodologies can be used as a valuable guide, inspiring new research on developing novel horizons for MIP applications to have their potential emphasized in analytical science and enhanced to the great analytical methods achievement.

Research progress of sensors based on molecularly imprinted polymers in analytical and biomedical analysis

Molecularly imprinted polymers (MIPs) have had tremendous impact on biomimetic recognition due to their precise specificity and high affinity comparable to that of antibodies, which has shown the great advantages of easy preparation, good stability and low cost. The combination of MIPs with other analytical technologies can not only achieve rapid extraction and sensitive detection of target compounds, improving the level of analysis, but also achieve precise targeted delivery, in-vivo imaging and other applications. Among them, the recognition mechanism plays a vital role in chemical and biological sensing, while the improvement of the recognition element, such as the addition of new nanomaterials, can greatly improve the analytical performance of the sensor, especially in terms of selectivity. Currently, due to the need for rapid diagnosis and improved sensing properties (such as selectivity, stability, and cost-effectiveness), researchers are investigating new recognition elements and their combinations to improve the recognition capabilities of chemical sensing and bio-sensing. Therefore, this review mainly discusses the design strategies of optical sensors, electrochemical sensors and photoelectric sensors with molecular imprinting technology and their applications in environmental systems, food fields, drug detection and biology including bacteria and viruses.

Determination of Neopterin as a Prognostic Indicator Using Neopterin-Imprinted Cryogel Membranes

Neopterin (Neo) is thought of as a key biomarker for the diagnosis and prognosis of a wide variety of diseases associated with cellular immune response. Therefore, it has become a vital need to be able to specifically determine the Neo concentration in human serum. Molecularly imprinted cryogels have come into prominence among other affinity systems by combining advantages of Molecular Imprinting Technology (MIT) and cryogels. In this chapter, synthesis of novel Neopterin-imprinted cryogel membranes (Neo-mip), characterization studies of synthesized materials, and their use in the determination of Neo in human serum is described in detail. In addition, the evaluation of selective Neo adsorption properties of Neo-mip against competitors (Pterin and Glucose) is discussed. Neo-mip will come into prominence as important affinity materials for the selective Neo recognition in body fluids, prior to use in the health sector.

Molecularly imprinted monoliths: Recent advances in the selective recognition of biomacromolecules related biomarkers

Biomarkers are significant indicators to assist the early diagnosis of diseases and assess the therapeutic response. However, due to the low-abundance of biomarkers in complex biological fluids, it is highly desirable to explore efficient techniques to attain their selective recognition and capture before the detection. Molecularly imprinted monoliths integrate the high selectivity of imprinted polymers and the rapid convective mass transport of monoliths, and as a result are promising candidates to achieve the specific enrichment of biomarkers from complex samples. This review summarizes the various imprinting approaches for the preparation of molecularly imprinted monoliths. The state-of-art advances as an effective platform for applications in the selective capture of biomacromolecules related biomarkers were also outlined. This article is protected by copyright. All rights reserved.

[Preparation of liquid crystal-based molecularly imprinted monolith and its molecular recognition thermodynamics]

Molecularly imprinted polymers (MIPs) incorporated with liquid crystalline monomers can imprint and recognize templates at a very low level of crosslinking, thus addressing challenges associated with conventional MIPs, such as the embedding of the imprinted sites, low binding capacity, and slow mass transfer due to the high degree of crosslinking. Compared with traditional MIPs, the prepared MIPs have a greater number of easily binding sites, which can effectively overcome the embedding and low utilization of imprinting sites. Simultaneously, with a decrease in the level of chemical crosslinking, the mass transfer of template molecules can be significantly improved. However, the imprinting effect of liquid crystalline MIPs is generally weaker than that of traditional MIPs due to the low degree of crosslinking. Therefore, to obtain liquid crystalline MIPs with a good imprinting effect, a series of low-crosslinked liquid crystalline molecularly imprinted monoliths were prepared by graft polymerization and evaluated by high performance liquid chromatography (HPLC) to systematically determine the relation between the polymerization parameters and the affinity of the resulting liquid crystalline MIPs. In this experiment, trimethylolpropane trimethacrylate (TRIM) was used to synthesize a monolithic column skeleton with toluene and dodecyl alcohol as porogens. (S)-Naproxen was used as a template and liquid crystalline monomer 4-(4-cyanophenyl)-cyclohexyl ethylene (CPCE) was added for grafting to synthesize the liquid crystalline MIP monolith. The influence of the acetonitrile content and pH in the mobile phase on the chromatographic retention of the template molecule was investigated. The results showed that the main force of MIP recognizing naproxen changed from hydrogen bonding to hydrophobic interaction by the addition of the liquid crystalline monomer. Frontal analysis and adsorption isotherm fitting, including Langmuir, Freundlich, and Scatchard fitting, showed that when the crosslinking degree was 15%, the liquid crystalline MIPs exhibited the highest imprinting factor and heterogeneity, and the specific adsorption was stronger than non-specific adsorption. By analyzing the stoichiometric displacement model, the total affinity of the MIP monoliths for the template molecules (ln A) was determined to be 0.645, significantly higher than that of its analogues, indicating that the liquid crystalline imprinted monolith had a higher total affinity for the template molecule. The spatial matching degree (nβ) of the template molecule to the cavity structures of MIPs was also very high, and only inferior to that of ketoprofen. Nevertheless, the ln A value of ketoprofen was only 0.242, which indicated that the spatial effect was not the key factor in determining the recognition ability of liquid crystalline imprinting systems. An analysis of the separation thermodynamics revealed that the separation of the liquid crystalline MIPs was an entropy-controlled process, while that of conventional liquid crystalline-free MIPs was an enthalpy-controlled process. Based on the above results, the addition of a liquid crystalline monomer may alter the recognition mechanism of MIPs, and an appropriately low crosslinking degree can significantly improve the recognition performance of liquid crystalline MIPs, paving the way for a new generation of MIPs.

Preparation and applications of electrochemical chemosensors based on carbon-nanomaterial-modified molecularly imprinted polymers

The past few decades have witnessed a rapid development in electrochemical chemosensors (ECCSs). The integration of carbon nanomaterials (CNMs) and molecularly imprinted polymers (MIPs) has endowed ECCSs with high selectivity and sensitivity toward target detection. Due to the integrated merits of MIPs and CNMs, CNM-modified MIPs as ECCSs have been widely reported and have excellent detection applications. This review systematically summarized the general categories, preparation strategies, and applications of ECCSs based on CNM-modified MIPs. The categories include CNM-modified MIPs often hybridized with various materials and CNM-encapsulated or CNM-combined imprinting silica and polymers on working electrodes or other substrates. The preparation strategies include the polymerization of MIPs on CNM-modified substrates, co-polymerization of MIPs and CNMs on substrates, drop-casting of MIPs on CNM-modified substrates, self-assembly of CNMs/MIP complexes on substrates, and so forth. We discussed the in situ polymerization, electro-polymerization, and engineering structures of CNM-modified MIPs. With regard to potential applications, we elaborated the detection mechanisms, signal transducer modes, target types, and electrochemical sensing of targets in real samples. In addition, this review discussed the present status, challenges, and prospects of CNM-modified MIP-based ECCSs. This comprehensive review is desirable for scientists from broad research fields and can promote the further development of MIP-based functional materials, CNM-based hybrid materials, advanced composites, and hybrid materials.

Nanomaterial-doped conducting polymers for electrochemical sensors and biosensors

This review summarizes recent advances in the development of electrochemical sensors and biosensors based on nanomaterial doped conducting polymers.

Facile construction of reduced graphene oxide–carbon dot complex embedded molecularly imprinted polymers for dual-amplification and selective electrochemical sensing of rutoside

This article reported reduced graphene oxide–carbon dot embedded molecularly imprinted polymers for sensitive and selective electrochemical sensing of rutoside.

Application of molecularly imprinted polymers in wastewater treatment: a review

Molecularly imprinted polymers are synthetic polymers possessing specific cavities designed for target molecules. They are prepared by copolymerization of a cross-linking agent with the complex formed from a template and monomers that have functional groups specifically interacting with the template through covalent or noncovalent bonds. Subsequent removal of the imprint template leaves specific cavities whose shape, size, and functional groups are complementary to the template molecule. Because of their predetermined selectivity, molecularly imprinted polymers (MIPs) can be used as ideal materials in wastewater treatment. Especially, MIP-based composites offer a wide range of potentialities in wastewater treatment. This paper reviews the latest applications of MIPs in wastewater treatment, highlights the development of MIP-based composites in wastewater, and offers suggestions for future success in the field of MIPs.

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.

Molecularly imprinted protein recognition cavities bearing exchangeable binding sites for postimprinting site-directed introduction of reporter molecules for readout of binding events

Protein-imprinted cavities bearing exchangeable domains to be used for postimprinting fluorophore introduction to transform binding events into fluorescence changes were constructed in molecularly imprinted polymer (MIPs) matrixes prepared on glass substrates. Copolymerization was performed with acrylamide, N,N'-methylenebisaclylamide, and a newly designed functional group-exchangeable monomer, ({[2-(2-methacrylamido)ethyldithio]ethylcarbamoyl}methoxy)acetic acid (MDTA), in the presence of a model basic protein, lysozyme (Lyso); MDTA can interact with Lyso and assemble close to Lyso in the resulting polymer. After removal of Lyso, followed by a disulfide reduction to cleave the (ethylcarbamoylmethoxy)acetic acid moiety from the MDTA residues, the exposed thiol groups within the imprinted cavities were modified by aminoethylpyridyldisulfide to be transformed into aminoethyl groups that function as active sites for amine-reactive fluorophores. Fluorescein isothiocyanate (FITC) was then coupled with the aminoethyl groups, yielding site specifically FITC-modified signaling imprinted cavities for Lyso binding. Because the in-cavity fluorescent labeling was achieved via a disulfide linkage, it was easy to remove, exchange, and/or replace amine-reactive fluorophores. This facilitated the screening of fluorophores to select the highest readout for binding events, replace fluorophores when photobleaching occurred, and introduce other functions. The proposed molecular imprinting process, combined with postimprinting modifications, is expected to provide an affordable route to develop multifunctional MIPs for specific detection of protein binding events.

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.