Molecularly Imprinted Polymers for the Identification and Separation of Chiral Drugs and Biomolecules

Highly Stable Flexible SERS-Imprinted Membrane Based on Plasmonic MOF Material for the Selective Detection of Chrysoidin in Environmental Water

Chrysoidin (CG) can be ingested into the human body through the skin and cause chronic toxicity, so the detection of CG levels in the environment is crucial. In this study, we synthesize F-Ag@ZIF-8/PVC molecular-imprinted membranes (FZAP-MIM) by an innovative combination of SERS detection, membrane separation, and a molecular-imprinted technique in order to perform the analysis of CG in water. The plasmonic MOF material as a SERS substrate helps to enrich the target and realize the spatial overlap of the target with the nanoparticle tip "hotspot". To avoid the poor reproducibility of Raman signals caused by the random arrangement of the powder substrate, polyvinyl chloride (PVC) is used to provide support and protection for the powder substrate. PVC has excellent dirt immunity and chemical stability, enabling the substrate to maintain Raman performance under complex and extreme detection conditions. FAZP-MIM has outstanding sensitivity and selectivity and can quickly and accurately capture targets even in the presence of similar structural interferences. The method showed superior recoveries in spiked recovery tests of real water samples and is expected to be practically applied to the trace detection of organic dye molecules in the environment.

Electrochemical sensors based on molecularly imprinted polymers for the detection of chlorophenols as emergent distributing chemicals (EDCs): a review

Environmental pollutants like chlorophenol chemicals and their derivatives are commonplace. These compounds serve as building blocks in the production of medicines, biocides, dyes, and agricultural chemicals. Chlorophenols enter the environment through several different pathways, including the breakdown of complex chlorinated hydrocarbons, industrial waste, herbicides, and insecticides. Chlorophenols are destroyed thermally and chemically, creating dangerous chemicals that pose a threat to public health. Water in particular is affected, and thorough monitoring is required to find this source of pollution because it can pose a major hazard to both human and environmental health. For the detection of chlorophenols, molecularly imprinted polymers (MIPs) have been incorporated into a variety of electrochemical sensing systems and assay formats. Due to their long-term chemical and physical stability as well as their simple and affordable synthesis process, MIPs have become intriguing synthetic alternatives over the past few decades. In this review, we concentrate on the commercial potential of the MIP technology. Additionally, we want to outline the most recent advancements in their incorporation into electrochemical sensors with a high commercial potential for detecting chlorophenols.

Chiral Materials: Progress, Applications, and Prospects

Chirality is a universal phenomenon in molecular and biological systems, denoting an asymmetric configurational property where an object cannot be superimposed onto its mirror image by any kind of translation or rotation, which is ubiquitous on the scale from neutrinos to spiral galaxies. Chirality plays a very important role in the life system. Many biological molecules in the life body show chirality, such as the "codebook" of the earth's biological diversity-DNA, nucleic acid, etc. Intriguingly, living organisms hierarchically consist of homochiral building blocks, for example, l-amino acids and d-sugars with unknown reason. When molecules with chirality interact with these chiral factors, only one conformation favors the positive development of life, that is, the chiral host environment can only selectively interact with chiral molecules of one of the conformations. The differences in chiral interactions are often manifested by chiral recognition, mutual matching, and interactions with chiral molecules, which means that the stereoselectivity of chiral molecules can produce changes in pharmacodynamics and pathology. Here, the latest investigations are summarized including the construction and applications of chiral materials based on natural small molecules as chiral source, natural biomacromolecules as chiral sources, and the material synthesized by design as a chiral source.

Bile Acid Sequestrants Based on Natural and Synthetic Gels

Bile acid sequestrants (BASs) are non-systemic therapeutic agents used for the management of hypercholesterolemia. They are generally safe and not associated with serious systemic adverse effects. Usually, BASs are cationic polymeric gels that have the ability to bind bile salts in the small intestine and eliminate them by excretion of the non-absorbable polymer-bile salt complex. This review gives a general presentation of bile acids and the characteristics and mechanisms of action of BASs. The chemical structures and methods of synthesis are shown for commercial BASs of first- (cholestyramine, colextran, and colestipol) and second-generation (colesevelam and colestilan) and potential BASs. The latter are based on either synthetic polymers such as poly((meth)acrylates/acrylamides), poly(alkylamines), poly(allylamines) and vinyl benzyl amino polymers or biopolymers, such as cellulose, dextran, pullulan, methylan, and poly(cyclodextrins). A separate section is dedicated to molecular imprinting polymers (MIPs) because of their great selectivity and affinity for the template molecules used in the imprinting technique. Focus is given to the understanding of the relationships between the chemical structure of these cross-linked polymers and their potential to bind bile salts. The synthetic pathways used in obtaining BASs and their in vitro and in vivo hypolipidemic activities are also introduced.

Molecularly Imprinted Polymer-Based Biomimetic Systems for Sensing Environmental Contaminants, Biomarkers, and Bioimaging Applications

Molecularly imprinted polymers (MIPs), a biomimetic artificial receptor system inspired by the human body's antibody-antigen reactions, have gained significant attraction in the area of sensor development applications, especially in the areas of medical, pharmaceutical, food quality control, and the environment. MIPs are found to enhance the sensitivity and specificity of typical optical and electrochemical sensors severalfold with their precise binding to the analytes of choice. In this review, different polymerization chemistries, strategies used in the synthesis of MIPs, and various factors influencing the imprinting parameters to achieve high-performing MIPs are explained in depth. This review also highlights the recent developments in the field, such as MIP-based nanocomposites through nanoscale imprinting, MIP-based thin layers through surface imprinting, and other latest advancements in the sensor field. Furthermore, the role of MIPs in enhancing the sensitivity and specificity of sensors, especially optical and electrochemical sensors, is elaborated. In the later part of the review, applications of MIP-based optical and electrochemical sensors for the detection of biomarkers, enzymes, bacteria, viruses, and various emerging micropollutants like pharmaceutical drugs, pesticides, and heavy metal ions are discussed in detail. Finally, MIP's role in bioimaging applications is elucidated with a critical assessment of the future research directions for MIP-based biomimetic systems.

Raclopride-Molecularly Imprinted Polymers: A Promising Technology for Selective [11C]Raclopride Purification

In this work, we developed a novel approach to purify [¹¹C]Raclopride ([¹¹C]RAC), an important positron emission tomography radiotracer, based on tailored shape-recognition polymers, with the aim to substitute single-pass HPLC purification with an in-flow trap & release process. Molecular imprinting technology (MIT) applied to solid phase extraction (MISPE) was investigated to develop a setting able to selectively extract [¹¹C]RAC in a mixture containing a high amount of its precursor, (S)-O-Des-Methyl-Raclopride (DM-RAC). Two imprinted polymers selective for unlabeled RAC and DM-RAC were synthesized through a radical polymerization at 65 °C using methacrylic acid and trimethylolpropane trimethacrylate in the presence of template molecule (RAC or DM-RAC). The prepared polymer was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy and tested in MISPE experiments. The polymers were used in testing conditions, revealing a high retention capacity of RAC-MISPE to retain RAC either in the presence of similar concentrations of RAC and DM-RAC precursor (96.9%, RSD 6.6%) and in the presence of a large excess of precursor (90%, RSD 4.6%) in the loading solution. Starting from these promising results, preliminary studies for selective purification of [¹¹C]Raclopride using this RAC-MISPE were performed and, while generally confirming the selectivity capacity of the polymer, revealed challenging applicability to the current synthetic process, mainly due to high backpressures and long elution times.

DNA-Immobilized Special Conformation Recognition of L-Penicillamine Using a Chiral Molecular Imprinting Technique

A new chiral molecularly imprinted polymer (MIP) sensor with dual recognition ability was developed for the highly selective separation of enantiomers with toxic side effects in drugs. The sensor contains double-stranded deoxyribonucleic acid (dsDNA) as the element that immobilizes the chiral molecular conformation: the dsDNA enables the imprinted cavities to match the three-dimensional structure and functional groups from the chiral molecule. By embedding the spatial orientation of dsDNA in MIPs, one can accurately capture and immobilize the molecular conformation, eliminating the influence of interfering analogues. Herein, L-penicillamine (L-Pen) was selected as the chiral template molecule and embedded into dsDNA to form dsDNA-L-Pen complex, which was then embedded into the MIPs by electropolymerization. After elution, the stereo-selective imprinted cavities were obtained. The ATATATATATAT-TATATATATATA base sequence showed a high affinity for the embedded L-Pen, which endowed the imprinted cavities with a larger number of sites and improved the selectivity toward Pen enantiomers. Under the optimal working conditions, the current response of the MIP/dsDNA sensor exhibited a positive linear relationship with the logarithm of the L-Pen concentration in the range of 3.0 × 10^-16 to 3.0 × 10^-13 mol/L, and the detection limit was 2.48 × 10^-16 mol/L. After the introduction of dsDNA into the MIP, the selectivity of the sensor toward D-Pen increased by 6.4 times, and the sensor was successfully applied in the analysis of L-Pen in penicillamine tablets.

Green Chemistry and Molecularly Imprinted Membranes

Technological progress has made chemistry assume a role of primary importance in our daily life. However, the worsening of the level of environmental pollution is increasingly leading to the realization of more eco-friendly chemical processes due to the advent of green chemistry. The challenge of green chemistry is to produce more and better while consuming and rejecting less. It represents a profitable approach to address environmental problems and the new demands of industrial competitiveness. The concept of green chemistry finds application in several material syntheses such as organic, inorganic, and coordination materials and nanomaterials. One of the different goals pursued in the field of materials science is the application of GC for producing sustainable green polymers and membranes. In this context, extremely relevant is the application of green chemistry in the production of imprinted materials by means of its combination with molecular imprinting technology. Referring to this issue, in the present review, the application of the concept of green chemistry in the production of polymeric materials is discussed. In addition, the principles of green molecular imprinting as well as their application in developing greenificated, imprinted polymers and membranes are presented. In particular, green actions (e.g., the use of harmless chemicals, natural polymers, ultrasound-assisted synthesis and extraction, supercritical CO2, etc.) characterizing the imprinting and the post-imprinting process for producing green molecularly imprinted membranes are highlighted.

Arsenic(III) and Arsenic(V) Removal from Water Sources by Molecularly Imprinted Polymers (MIPs): A Mini Review of Recent Developments

The present review article summarizes the recent findings reported in the literature with regard to the use of molecularly imprinted polymers for the removal of arsenic from water and wastewater. MIPs are polymers in which a template is employed in order to enable the formation of recognition sites during the covalent assembly of the bulk phase, via a polymerization or polycondensation process. The efficiency of both arsenic species and the mechanism of removal are highlighted. The results have shown that under certain conditions, MIPs demonstrated arsenic sorption capacities of up to 130 mg/g for As(V) and 151 mg/g for As(III), while the regeneration ability was found to reach up to more than 20 cycles. The overall results showed that further development of MIPs could result in the formation of promising adsorbents for arsenic removal from waters. The use of MIPs for the removal not only of arsenic but also other inorganic contaminants is considered a very important topic, with great potential in terms of future applications in water treatment. The main advantage of these materials is that they are very selective toward the contaminant of interest. This enhanced selectivity is attributed to the incorporation of specific templates, which can then adsorb the contaminant of interest almost exclusively. Therefore, the main problem in adsorption processes is the competition for adsorption sites by other water components, for example, phosphates, nitrates, carbonates, and sulfates, which can be circumvented by the use of MI-type adsorbents.

Cobalt (II)-Mediated Molecularly Imprinted Polymer as a Monolithic Stationary Phase for Separation of Racemic Citronellal by Liquid Chromatography

A metal-mediated molecularly imprinted polymer (MMIP) monolithic column was prepared as the stationary phase for high-performance liquid chromatography (HPLC) and applied to the enantiomeric separation of rac-citronellal. MMIP column was prepared through in situ copolymerizations with the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate/[BMIM][BF₄] as the primary pore-forming agent and cobalt(II) acetate as the metal pivot. Interactions between polymer components in the synthesized monolith were assessed by FTIR to identify the functional groups. The monolith morphology was characterized with SEM, and the template removal was detected by UV Spectrophotometry at 253 nm. In this study, (R)-(+)-citronellal was used as a template, whereas 4-vinylpyridine (4-VP) was employed as the functional monomer with two monomer crosslinkers, trimethylolpropane trimethacrylate (TRIM), and ethylene glycol dimethacrylate (EDMA). The ternary mixture of porogenic solvent consisted of [BMIM][BF₄], dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) with the applied ratio of 1 : 1:1 (v/v) and 10 : 1:5 (v/v) for the preparation of MMIP using TRIM and EDMA crosslinkers, respectively. Co(II) ion was added to the porogenic solvent before being mixed with the functional monomer and the crosslinker mixtures. Separating the rac-citronellal was achieved on the synthesized MMIP, showing better selectivity than the monolithic metal-mediated nonimprinted polymer (MNIP), nonimprinted polymer (NIP), and molecularly imprinted polymer (MIP).

Chromatographic performance of zidovudine imprinted polymers coated silica stationary phases

Nowadays, molecularly imprinted polymers (MIPs) coated silica stationary phases (SPs) have aroused great attention, owing to their good properties of high selectivity, good stability, facile synthesis procedure and low cost. In this study, zidovudine imprinted polymers coated silica stationary phases (MIPs/SiO₂ SPs) were synthesized by surface imprinting technique using zidovudine as the template molecule, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linking agent, azobisisobutyronitrile as the initiator, and bare silica spheres (particle size, 5 μm; pore size, 20 nm) as substrates. In the process, reagents with low concentration were used to prepare thin layer of MIPs coating on the surface of silica microbeads. The properties of the materials were characterized by scanning electron microscope (SEM), fourier transform infrared spectrometer (FT-IR), carbon elemental analysis and N₂ adsorption-desorption experiment. The obtained SPs were packed into stainless steel columns (2.1 mm × 150 mm) via a slurry method. The prepared columns were applied for separation of nucleoside analogues with similar chemical structures and strong polarity. The retention mechanism of MIPs/SiO₂ SPs for nucleoside analogues was investigated carefully. And the chromatographic performances of the resulting MIPs based SPs were superior to those of the commercial SPs. Furthermore, the synthesized MIPs/SiO₂ SPs possessed great potentials in separation of ginsenosides. This investigation demonstrated that MIPs based SPs were successfully synthesized and provided a new approach to polar compounds separation and analysis.

Molecularly Imprinted Polymers (MIPs) in Sensors for Environmental and Biomedical Applications: A Review

Molecular imprinted polymers are custom made materials with specific recognition sites for a target molecule. Their specificity and the variety of materials and physical shapes in which they can be fabricated make them ideal components for sensing platforms. Despite their excellent properties, MIP-based sensors have rarely left the academic laboratory environment. This work presents a comprehensive review of recent reports in the environmental and biomedical fields, with a focus on electrochemical and optical signaling mechanisms. The discussion aims to identify knowledge gaps that hinder the translation of MIP-based technology from research laboratories to commercialization.

Molecularly imprinted polymer coated Mn-doped ZnS quantum dots embedded in a metal-organic framework as a probe for selective room temperature phosphorescence detection of chlorpyrifos

As one of the most widely used organophosphorus pesticides, chlorpyrifos (CPF) is toxic to humans. However, the rapid, effective and sensitive detection of CPF is still a challenge. In this paper, a novel molecularly imprinted phosphorescent sensor with a core–shell structure (Mn:ZnS QDs@ZIF-8@MIP) using Mn:ZnS quantum dots (QDs) as phosphorescent emitters was prepared for the highly sensitive and selective detection of CPF, and a simple and rapid room-temperature phosphorescence (RTP) detection method for CPF was proposed. For the prepared Mn:ZnS QDs@ZIF-8@MIP, Mn:ZnS QDs had good phosphorescence emission characteristics, ZIF-8 as support materials was used to improve the dispersibility of Mn:ZnS QDs, and molecularly imprinted polymer (MIP) on the surface of ZIF-8 was used to improve the selectivity of Mn:ZnS QDs for CPF. Under the optimal response conditions, the RTP intensity of Mn:ZnS QDs@ZIF-8@MIP showed a rapid response to CPF (less than 5 min), the RTP intensity ratio of P₀/P had a good linear relationship with the concentration of CPF in the range of 0–80 μM, and the detection limit of this method was 0.89 μM with the correlation coefficient of 0.99. Moreover, this simple and rapid method has been successfully used to detect CPF in real water samples with satisfactory results, and the recoveries ranged from 92% to 105% with a relative standard deviation of less than 1%. This method combines the advantages of phosphorescence emission and molecular imprinting, and greatly reduces the potential interferences of competitive substances, background fluorescence and scattered light, which opens up a broad prospect for the highly sensitive and selective detection of pollutants in water based on molecularly imprinted phosphorescent sensors.

As one of the most widely used organophosphorus pesticides, chlorpyrifos (CPF) is toxic to humans, and Mn:ZnS QDs@ZIF-8@MIP are prepared for the highly sensitive and selective detection of CPF.

Bile acid sequestrants: a review of mechanism and design

OBJECTIVE

Bile acid sequestrants (BAS) are used extensively in the treatment of hypercholesterolaemia. This brief review aimed to describe the design and evaluation of three types of BAS: amphiphilic copolymers, cyclodextrin/poly-cyclodextrin and molecular imprinted polymers. The mechanisms underlying the action of BAS are also discussed.

KEY FINDINGS

BAS could lower plasma cholesterol, improve glycemic control in patients with type 2 diabetes and regulate balance energy metabolism via receptors or receptor-independent mediated mechanisms. Different types of BAS have different levels of ability to bind to bile acids, different stability and different in-vivo activity.

CONCLUSIONS

A growing amount of evidence suggests that bile acids play important roles not only in lipid metabolism but also in glucose metabolism. The higher selectivity, specificity, stability and in-vivo activity of BAS show considerable potential for lipid-lowering therapy.

Effect of the Molecularly Imprinted Polymer Component Ratio on Analytical Performance

Molecular imprinting technology is a new analytical method that is highly selective and specific for certain analytes in artificial receptor design. The renewal possibilities of this technology make it an ideal material for sundry application fields. Molecularly imprinted polymers (MIPs) are polymeric matrices that have molecules printed on their surfaces; these surfaces can chemically interact with molecules or follow the pattern of the available template cavities obtained using imprinting technology. A MIP is useful for separating and analysing complex samples, such as biological fluids and environmental samples, because it is a strong analytical recognition element that can mimick natural recognition entities like biological receptors and antibodies. The MIP components consist of the target template, functional monomer, crosslinker, polymerisation initiator, and porogen. The effectiveness and selectivity of a MIP are greatly influenced by variations in the components. This review will provide an overview of the effect of MIP component ratio on analytical performance to each target analyte; it will also provide a strategy to obtain the best MIP performance. For every MIP, each template : monomer : crosslinker ratio shows a distinct performance for a specific analyte. The effects of the template : monomer : crosslinker ratio on a MIP's analytical performances-measured by the imprinting factor, sorbent binding capacity, and sorbent selectivity-are briefly outlined.

The Importance of Developing Electrochemical Sensors Based on Molecularly Imprinted Polymers for a Rapid Detection of Antioxidants

This review aims to pin out the importance of developing a technique for rapid detection of antioxidants, based on molecular imprinting techniques. It covers three major areas that have made great progress over the years in the field of research, namely: antioxidants characterization, molecular imprinting and electrochemistry, alone or combined. It also reveals the importance of bringing these three areas together for a good evaluation of antioxidants in a simple or complex medium, based on selectivity and specificity. Although numerous studies have associated antioxidants with molecular imprinting, or antioxidants with electrochemistry, but even electrochemistry with molecular imprinting to valorize different compounds, the growing prominence of antioxidants in the food, medical, and paramedical sectors deserves to combine the three areas, which may lead to innovative industrial applications with satisfactory results for both manufacturers and consumers.

Chiral Recognition for Chromatography and Membrane-Based Separations: Recent Developments and Future Prospects

With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug enantiomers is caused by differential enantiospecific binding to receptors. This review is devoted to the specific recognition and resolution of chiral molecules by chromatography and membrane-based enantioseparation techniques. Chromatographic enantiomer separations with chiral stationary phase (CSP)-based columns and membrane-based enantiomer filtration are detailed. In addition, the unique properties of these chiral resolution methods have been summarized for practical applications in the chemistry, environment, biology, medicine, and food industries. We further discussed the recognition mechanism in analytical enantioseparations and analyzed recent developments and future prospects of chromatographic and membrane-based enantioseparations.

Contribution to the Understanding of the Interaction between a Polydopamine Molecular Imprint and a Protein Model: Ionic Strength and pH Effect Investigation

Several studies were devoted to the design of molecularly imprinted polymer (MIP)-based sensors for the detection of a given protein. Here, we bring elements that could contribute to the understanding of the interaction mechanism involved in the recognition of a protein by an imprint. For this purpose, a polydopamine (PDA)-MIP was designed for bovine serum albumin (BSA) recognition. Prior to BSA grafting, the gold surfaces were functionalized with mixed self-assembled monolayers of (MUDA)/(MHOH) (1/9, v/v). The MIP was then elaborated by dopamine electropolymerization and further extraction of BSA templates by incubating the electrode in proteinase K solution. Three complementary techniques, electrochemistry, zetametry, and Fourier-transform infrared spectrometry, were used to investigate pH and ionic strength effects on a MIP's design and the further recognition process of the analytes by the imprints. Several MIPs were thus designed in acidic, neutral, and basic media and at various ionic strength values. Results indicate that the most appropriate conditions, to achieve a successful MIPs, were an ionic strength of 167 mM and a pH of 7.4. Sensitivity and dissociation constant of the designed sensor were of order of (3.36 ± 0.13) µA·cm-2·mg-1·mL and (8.56 ± 6.09) × 10-11 mg/mL, respectively.

Past, present, and future developments in enantioselective analysis using capillary electromigration techniques

Enantioseparation of chiral products has become increasingly important in a large diversity of academic and industrial applications. The separation of chiral compounds is inherently challenging and thus requires a suitable analytical technique that can achieve high resolution and sensitivity. In this context, CE has shown remarkable results so far. Chiral CE offers an orthogonal enantioselectivity and is typically considered less costly than chromatographic techniques, since only minute amounts of chiral selectors are needed. Several CE approaches have been developed for chiral analysis, including chiral EKC and chiral CEC. Enantioseparations by EKC benefit from the wide variety of possible pseudostationary phases that can be employed. Chiral CEC, on the other hand, combines chromatographic separation principles with the bulk fluid movement of CE, benefitting from reduced band broadening as compared to pressure-driven systems. Although UV detection is conventionally used for these approaches, MS can also be considered. CE-MS represents a promising alternative due to the increased sensitivity and selectivity, enabling the chiral analysis of complex samples. The potential contamination of the MS ion source in EKC-MS can be overcome using partial-filling and counter-migration techniques. However, chiral analysis using monolithic and open-tubular CEC-MS awaits additional method validation and a dedicated commercial interface. Further efforts in chiral CE are expected toward the improvement of existing techniques, the development of novel pseudostationary phases, and establishing the use of chiral ionic liquids, molecular imprinted polymers, and metal-organic frameworks. These developments will certainly foster the adoption of CE(-MS) as a well-established technique in routine chiral analysis.

Recent Advances in Molecularly Imprinted Membranes for Sample Treatment and Separation

This review describes the recent advances from the past five years concerning the development and applications of molecularly imprinted membranes (MIMs) in the field of sample treatment and separation processes. After a short introduction, where the importance of these materials is highlighted, a description of key aspects of membrane separation followed by the strategies of preparation of these materials is described. The review continues with several analytical applications of these MIMs for sample preparation as well as for separation purposes covering pharmaceutical, food, and environmental areas. Finally, a discussion focused on possible future directions of these materials in extraction and separation field is also given.

Advancements of chiral molecularly imprinted polymers in separation and sensor fields: A review of the last decade

Since chiral recognition mechanism based on molecularly imprinted polymers immerged, it has assisted countless chemical and electrochemical analytical sample preparation techniques. It has done this by enhancing the enatioseparation abilities of these techniques. The preparation and optimization of chiral molecularly imprinted polymers (CMIPs) are two favored methods in the separation and sensor fields. This review aims to present an overview of advances in the preparation and application of CMIPs in analytical approaches in different available formats (eg. column, monolithic column, cartridge, membrane, nanomaterials, pipette tip and stir bar sorptive) over the last decade. In addition, progress in the preparation and development of CMIPs-based sensor fields have been also discussed. Finally, the main application challenges of CMIPs are also summarily explained, as well as upcoming prospects in the field.

Molecularly imprinted polymer-based electrochemical sensors for environmental analysis

The ever-increasing presence of contaminants in environmental waters is an alarming issue, not only because of their harmful effects in the environment but also because of their risk to human health. Pharmaceuticals and pesticides, among other compounds of daily use, such as personal care products or plasticisers, are being released into water bodies. This release mainly occurs through wastewater since the treatments applied in many wastewater treatment plants are not able to completely remove these substances. Therefore, the analysis of these contaminants is essential but this is difficult due to the great variety of contaminating substances. Facing this analytical challenge, electrochemical sensing based on molecularly imprinted polymers (MIPs) has become an interesting field for environmental monitoring. Benefiting from their superior chemical and physical stability, low-cost production, high selectivity and rapid response, MIPs combined with miniaturized electrochemical transducers offer the possibility to detect target analytes in-situ. In most reports, the construction of these sensors include nanomaterials to improve their analytical characteristics, especially their sensitivity. Moreover, these sensors have been successfully applied in real water samples without the need of laborious pre-treatment steps. This review provides a general overview of electrochemical MIP-based sensors that have been reported for the detection of pharmaceuticals, pesticides, heavy metals and other contaminants in water samples in the past decade. Special attention is given to the construction of the sensors, including different functional monomers, sensing platforms and materials employed to achieve the best sensitivity. Additionally, several parameters, such as the limit of detection, the linear concentration range and the type of water samples that were analysed are compiled.

Chiral Mesoporous Silica Materials: A Review on Synthetic Strategies and Applications

Because of its tunable textural properties and chirality feature, chiral mesoporous silica (CMS) gained significant consideration in many fields and has been developed rapidly in recent years. In this review, we provide an overview of synthesis strategies for fabricating CMS together with its main applications. The properties of CMS, including morphology and mesostructures and enantiomer excess (ee), can be altered according to the synthetic conditions during the synthesis process. Despite its primary stage, CMS has attracted extensive attention in many fields. In particular, CMS nanoparticles are widely used for enantioselective resolution and adsorption of chiral compounds with desirable separation capability. Also, CMS acts as a promising candidate for the effective delivery of chiral or achiral drugs to produce a chiral-responsive manner. Moreover, CMS also plays an important role in chromatographic separations and asymmetric catalysis. There has been an in-depth review of the synthetic methods and mechanisms of CMS. And this review aims to give a deep insight into the synthesis and application of CMS, especially in recent years, and highlights the significance that it may have in the future.

Molecularly Imprinted Polymer-Based Hybrid Materials for the Development of Optical Sensors

We report on the development of new optical sensors using molecularly imprinted polymers (MIPs) combined with different materials and explore the novel strategies followed in order to overcome some of the limitations found during the last decade in terms of performance. This review pretends to offer a general overview, mainly focused on the last 3 years, on how the new fabrication procedures enable the synthesis of hybrid materials enhancing not only the recognition ability of the polymer but the optical signal. Introduction describes MIPs as biomimetic recognition elements, their properties and applications, emphasizing on each step of the fabrication/recognition procedure. The state of the art is presented and the change in the publication trend between electrochemical and optical sensor devices is thoroughly discussed according to the new fabrication and micro/nano-structuring techniques paving the way for a new generation of MIP-based optical sensors. We want to offer the reader a different perspective based on the materials science in contrast to other overviews. Different substrates for anchoring MIPs are considered and distributed in different sections according to the dimensionality and the nature of the composite, highlighting the synergetic effect obtained as a result of merging both materials to achieve the final goal.

External strain-enhanced cysteine enantiomeric separation ability on alloyed stepped surfaces

Using density functional theory with an accurate treatment of van der Waals interactions, we investigate the enantioselective recognition and separation of chiral molecules on stepped metal surfaces. Our calculations demonstrate that the separation ability of metal substrates can be significantly enhanced by surface decoration and external strain. For example, applying 2% tensile strain to the Ag-alloyed Au(532) surface leads to a dramatic increase (by 89%) in cysteine enantioselectivity as compared to that of pristine Au(532). Analysis on the computed binding energies shows that the interaction energy is the predominant factor that affects the separation efficiency in strongly bound systems. Our study presents a new strategy to modify the enantioselectivity of stepped metal surfaces and paves the way for exploring high efficiency chiral separation technology in pharmaceutical industry.

Recent Advances in Electrosynthesized Molecularly Imprinted Polymer Sensing Platforms for Bioanalyte Detection

The accurate detection of biological materials has remained at the forefront of scientific research for decades. This includes the detection of molecules, proteins, and bacteria. Biomimetic sensors look to replicate the sensitive and selective mechanisms that are found in biological systems and incorporate these properties into functional sensing platforms. Molecularly imprinted polymers (MIPs) are synthetic receptors that can form high affinity binding sites complementary to the specific analyte of interest. They utilise the shape, size, and functionality to produce sensitive and selective recognition of target analytes. One route of synthesizing MIPs is through electropolymerization, utilising predominantly constant potential methods or cyclic voltammetry. This methodology allows for the formation of a polymer directly onto the surface of a transducer. The thickness, morphology, and topography of the films can be manipulated specifically for each template. Recently, numerous reviews have been published in the production and sensing applications of MIPs; however, there are few reports on the use of electrosynthesized MIPs (eMIPs). The number of publications and citations utilising eMIPs is increasing each year, with a review produced on the topic in 2012. This review will primarily focus on advancements from 2012 in the use of eMIPs in sensing platforms for the detection of biologically relevant materials, including the development of increased polymer layer dimensions for whole bacteria detection and the use of mixed monomer compositions to increase selectivity toward analytes.

Chiral Stationary Phases for Liquid Chromatography: Recent Developments

The planning and development of new chiral stationary phases (CSPs) for liquid chromatography (LC) are considered as continuous and evolutionary issues since the introduction of the first CSP in 1938. The main objectives of the development strategies were to attempt the improvement of the chromatographic enantioresolution performance of the CSPs as well as enlarge their versatility and range of applications. Additionally, the transition to ultra-high-performance LC were underscored. The most recent strategies have comprised the introduction of new chiral selectors, the use of new materials as chromatographic supports or the reduction of its particle size, and the application of different synthetic approaches for preparation of CSPs. This review gathered the most recent developments associated to the different types of CSPs providing an overview of the relevant advances that are arising on LC.

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.

Synthesis and characterization of paclitaxel-imprinted microparticles for controlled release of an anticancer drug

In this study, novel molecularly imprinted polymer (MIP) microparticles containing methacryl polyhedral oligomeric silsesquioxane (M-POSS) were synthesized through the RAFT precipitation polymerization (RAFTPP) method using paclitaxel (PTX) as the templates. During the course of this investigation, methacrylic acid (MAA) was used as the functional monomer, while ethylene glycol dimethacrylate (EGDMA) was utilized as a cross-linker. The effects of different molar ratios of M-POSS on the microparticles were characterized. The obtained MIP microparticles were confirmed by FT-IR and TGA-DSC. The results of SEM showed regular spherical-shaped MIP microparticles with diameters around 170-490 nm. The PTX loading quantity was closely correlated with the content of M-POSS, and the MIP microparticles showed a satisfactory affinity to PTX with high drug loading (17.1%) and encapsulation efficiency (85.5%). Moreover, these MIP microparticles were sensitive to pH, and consequently the release rates of PTX at pH 5 were much faster than those at pH 7 due to the acid cleavage of the hydrogen bonds. In addition, the results from release experiments of the MIP microparticles showed a very slow and controlled release of PTX, which heralded promising potential as a carrier for PTX delivery in cancer therapy.