Enzyme-like catalysis by molecularly imprinted polymers

Multiplexed neurochemical sensing with sub-nM sensitivity across 2.25 mm2 area

Multichannel arrays capable of real-time sensing of neuromodulators in the brain are crucial for gaining insights into new aspects of neural communication. However, measuring neurochemicals, such as dopamine, at low concentrations over large areas has proven challenging. In this research, we demonstrate a novel approach that leverages the scalability and processing power offered by microelectrode array devices integrated with a functionalized, high-density microwire bundle, enabling electrochemical sensing at an unprecedented scale and spatial resolution. The sensors demonstrate outstanding selective molecular recognition by incorporating a selective polymeric membrane. By combining cutting-edge commercial multiplexing, digitization, and data acquisition hardware with a bio-compatible and highly sensitive neurochemical interface array, we establish a powerful platform for neurochemical analysis. This multichannel array has been successfully utilized in vitro and ex vivo systems. Notably, our results show a sensing area of 2.25 mm2 with an impressive detection limit of 820 pM for dopamine. This new approach paves the way for investigating complex neurochemical processes and holds promise for advancing our understanding of brain function and neurological disorders.

DFT simulated Quercetin imprinted polymer: Selective recovery of Quercetin from onion solid waste

Onion peels (OP) are byproduct of food processing industries that poses economic and environmental challenges. However, being rich source of bioactive compounds like Quercetin (Qt), a polyphenolic antioxidant with potential health benefits, harnessing value from such waste can imbibe sustainable practices and protect environment. With this view, the present study targets selective recovery of Qt from OP waste using rationally designed molecularly imprinted polymer (MIP). Density Functional Theory (DFT) was used for the theoretical selection of the best conformer of Qt (template), methacrylic acid (MAA) as functional monomer, ratio of Qt-MAA for getting stable pre-polymerization complex, and to avoid hit and trial experiments. The theoretical results were validated experimentally by synthesizing MIP/ control polymer (NIP) using MAA as functional monomer, EGDMA as a cross-linker and AIBN as initiator. Synthesized MIP/NIP were characterized using various characterization techniques to confirm successful imprinting. Prepared MIP and NIP could effectively rebind the Qt molecule with binding capacity of 46.67 and 20.89 mg g-1 respectively. Furthermore, synthesized MIP could selectively recover 62.81 % of Qt from 1 g of dry onion peel powder. This study can be effectually used for sustainable recovery of Qt in large scale for various foods, cosmetic and pharmaceutical applications.

Computational design and preparation of water-compatible noncovalent imprinted microspheres

Herein, 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model template in a rational design strategy to produce water-compatible noncovalent imprinted microspheres. The proposed approach involved computational modelling for screening functional monomers and a simple method for preparing monodisperse and highly cross-linked microspheres. The fabricated non-imprinted polymer (NIP) and 2,4-d-imprinted polymer (2,4-d-MIP) were characterised, and their adsorption capabilities in an aqueous environment were evaluated. Results reveal that the pseudo-second-order kinetics model was appropriate for representing the adsorption of 2,4-D on NIP and 2,4-d-MIP, with R2 values of 0.97 and 0.99, respectively. The amount of 2,4-D adsorbed on 2,4-d-MIP (97.75 mg g-1) was considerably higher than those of phenoxyacetic acid (35.77 mg g-1), chlorogenic acid (9.72 mg g-1), spiramycin (1.56 mg g-1) and tylosin (1.67 mg g-1). Furthermore, it exhibited strong resistance to protein adsorption in an aqueous medium. These findings confirmed the feasibility of the proposed approach, providing a reference for the development of water-compatible noncovalent imprinted polymers.

Enhancing the substrate selectivity of enzyme mimetics in biosensing and bioassay: Novel approaches

A substantial development in nanoscale materials possessing catalytic activities comparable with natural enzymes has been accomplished. Their advantages were owing to the excellent sturdiness in an extreme environment, possibilities of their large-scale production resulting in higher profitability, and easy manipulation for modification. Despite these advantages, the main challenge for artificial enzyme mimetics is the lack of substrate selectivity where natural enzymes flourish. This review addresses this vital problem by introducing substrate selectivity strategies to three classes of artificial enzymes: molecularly imprinted polymers, nanozymes (NZs), and DNAzymes. These rationally designed strategies enhance the substrate selectivity and are discussed and exemplified throughout the review. Various functional mechanisms associated with applying enzyme mimetics in biosensing and bioassays are also given. Eventually, future directives toward enhancing the substrate selectivity of biomimetics and related challenges are discussed and evaluated based on their efficiency and convenience in biosensing and bioassays.

Advancing stroke therapy: the potential of MOF-based nanozymes in biomedical applications

In this study, we explored the growing use of metal-organic framework (MOF)-based Nanozymes in biomedical research, with a specific emphasis on their applications in stroke therapy. We have discussed the complex nature of stroke pathophysiology, highlighting the crucial role of reactive oxygen species (ROS), and acknowledging the limitations of natural enzymes in addressing these challenges. We have also discussed the role of nanozymes, particularly those based on MOFs, their structural similarities to natural enzymes, and their potential to improve reactivity in various biomedical applications. The categorization of MOF nanozymes based on enzyme-mimicking activities is discussed, and their applications in stroke therapy are explored. We have reported the potential of MOF in treating stroke by regulating ROS levels, alleviation inflammation, and reducing neuron apoptosis. Additionally, we have addressed the challenges in developing efficient antioxidant nanozyme systems for stroke treatment. The review concludes with the promise of addressing these challenges and highlights the promising future of MOF nanozymes in diverse medical applications, particularly in the field of stroke treatment.

Progress in cyclodextrins as important molecules regulating catalytic processes of glycoside hydrolases

Cyclodextrins (CDs) are important starch derivatives and commonly comprise α-, β-, and γ-CDs. Their hydrophilic surface and hydrophobic inner cavity enable regulation of enzyme catalysis through direct or indirect interactions. Clarifying interactions between CDs and enzyme is of great value for enzyme screening, mechanism exploration, regulation of catalysis, and applications. We summarize the interactions between CDs and glycoside hydrolases (GHs) according to two aspects: 1) CD as products, substrates, inhibitors and activators of enzymes, directly affecting the reaction process; 2) CDs indirectly affecting the enzymatic reaction by solubilizing substrates, relieving substrate/product inhibition, increasing recombinant enzyme production and storage stability, isolating and purifying enzymes, and serving as ligands in crystal structure to identify functional amino acid residues. Additionally, CD enzyme mimetics are developed and used as catalysts in traditional artificial enzymes as well as nanozymes, making the application of CDs no longer limited to GHs. This review concerns the regulation of GHs catalysis by CDs, and gives insights into research on interactions between enzymes and ligands.

Molecularly imprinted composite-based biosensor for the determination of SARS-CoV-2 nucleocapsid protein

This article aims to present a comparative study of three polypyrrole-based molecularly imprinted polymer (MIP) systems for the detection of the recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (rN). The rN is known for its relatively low propensity to mutate compared to other SARS-CoV-2 antigens. The aforementioned systems include screen-printed carbon electrodes (SPCE) modified with gold nanostructures (MIP1), platinum nanostructures (MIP2), and the unmodified SPCE (MIP3), which was used for control. Pulsed amperometric detection (PAD) was employed as the detection technique, offering the advantage of label-free detection without the need for an additional redox probe. Calibration curves were constructed using the obtained data to evaluate the response of each system. Non-imprinted systems were also tested in parallel to evaluate the contribution of non-specific binding and assess the affinity sensor's efficiency. The analysis of calibration curves revealed that the AuNS-based MIP1 system exhibited the lowest contribution of non-specific binding and displayed a better fit with the chosen fitting model compared to the other systems. Further analysis of this system included determining the limit of detection (LOD) (51.2 ± 2.8 pg/mL), the limit of quantification (LOQ) (153.9 ± 8.3 pg/mL), and a specificity test using a recombinant receptor-binding domain of SARS-CoV-2 spike protein as a control. Based on the results, the AuNS-based MIP1 system demonstrated high specificity and sensitivity for the label-free detection of SARS-CoV-2 nucleocapsid protein. The utilization of PAD without the need for additional redox probes makes this sensing system convenient and valuable for rapid and accurate virus detection.

Kink-Controlled Gold Nanoparticles for Electrochemical Glucose Oxidation

Enzymes in nature efficiently catalyze chiral organic molecules by elaborately tuning the geometrical arrangement of atoms in the active site. However, enantioselective oxidation of organic molecules by heterogeneous electrocatalysts is challenging because of the difficulty in controlling the asymmetric structures of the active sites on the electrodes. Here, we show that the distribution of chiral kink atoms on high-index facets can be precisely manipulated even on single gold nanoparticles; and this enabled stereoselective oxidation of hydroxyl groups on various sugar molecules. We characterized the crystallographic orientation and the density of kink atoms and investigated their specific interactions with the glucose molecule due to the geometrical structure and surface electrostatic potential.

Metal oxide nanomaterials based electrochemical and optical biosensors for biomedical applications: Recent advances and future prospectives

The amalgamation of nanostructures with modern electrochemical and optical techniques gave rise to interesting devices, so-called biosensors. A biosensor is an analytical tool that incorporates various biomolecules with an appropriate physicochemical transducer. Over the past few years, metal oxide nanomaterials (MONMs) have significantly stimulated biosensing research due to their desired functionalities, versatile chemical stability, and low cost along with their unique optical, catalytic, electrical, and adsorption properties that provide an attractive platform for linking the biomolecules, for example, antibodies, nucleic acids, enzymes, and receptor proteins as sensing elements with the transducer for the detection of signals or signal amplifications. The signals to be measured are in direct proportionate to the concentration of the bioanalyte. Because of their simplicity, cost-effectiveness, portability, quick analysis, higher sensitivity, and selectivity against a broad range of biosamples, MONMs-based electrochemical and optical biosensing platforms are exhaustively explored as powerful early-diagnosis tools for point of care applications. Herein, we made a bibliometric analysis of past twenty years (2004-2023) on the application of MONMs as electrochemical and optical biosensing units using Web of Science database and the results of which clearly reveal the increasing number of publications since 2004. Geographical area distribution analysis of these publications shows that China tops the list followed by the United States of America and India. In this review, we first describe the electrochemical and optical properties of MONMs that are crucial for the creation of extremely stable, specific, and sensitive sensors with desirable characteristics. Then, the biomedical applications of MONMs-based bare and hybrid electrochemical and optical biosensing frameworks are highlighted in the light of recent literature. Finally, current limitations and future challenges in the field of biosensing technology are addressed.

Improvement of the selectivity of a molecularly imprinted polymer-based potentiometric sensor by using a specific functional monomer

Potentiometric sensors based on the molecularly imprinted polymers (MIPs) as the receptors have been successfully developed for determination of various organic and biological species. However, these MIP receptors may suffer from problems of low selectivity. Especially, it would be difficult to distinguish the target analyte from its structurally similar interferents. In this work, we propose a novel strategy that using specific functional monomer to fabricate MIP with high selectivity towards the target molecule. The density functional theory calculations are used to investigate the interactions between the template and the functional monomer. The binding energy between the template and functional monomer can be used as the criterion for identifying the optimal monomer. As a proof-of-concept experiment, bisphenol A (BPA) is chosen as the template and the MIP is synthesized by the precipitation polymerization method using the specific allyl-β-cyclodextrin (allyl-β-CD) with high affinity towards BPA as the functional monomer. The high-affinity MIP is employed as the receptor for the construction of the potentiometric sensor. The proposed potentiometric sensor based on the MIP using allyl-β-CD as the functional monomer shows an improved response performance in terms of selectivity and sensitivity compared to the conventional potentiometric sensor based on the MIP with the common monomer (i.e., methacrylic acid). This allyl-β-CD MIP-based potentiometric sensor shows a detection limit of 0.29 μM for BPA, which is about one order of magnitude lower than that obtained by the conventional MIP-based potentiometric sensor. We believe that utilizing a functional monomer with specific recognition ability towards target in the fabrication of MIP could provide an appealing way to construct highly selective MIP-based electrochemical and optical sensors.

Tailor-made molecular imprints for biological event intervention

Molecular imprints, which are crosslinked architectures containing specific molecular recognition cavities for targeting compounds, have recently transitioned from in vitro diagnosis to in vivo treatment. In current application scenarios, it has become an important topic to create new biomolecular recognition pathways through molecular imprinting, thereby inhibiting the pathogenesis and regulating the development of diseases. This review starts with a pathological analysis, mainly focusing on the corresponding artificial enzymes, enzyme inhibitors and antibody mimics with enhanced functions that are created by molecular imprinting strategies. Recent advances are highlighted in the use of molecular imprints as tailor-made nanomedicines for the prevention of three major diseases: metabolic syndrome, cancer, and bacterial/viral infections.

Günter Wulff (1935 -2023): Father of Molecular Imprinting

Günter Wulff, internationally well known for his invention of Molecular Imprinting, passed away on December 11, 2023 in Erkrath-Hochdahl, Germany, not far from the University of Düsseldorf, where he made his greatest discoveries. A passionate researcher and deep conceptual thinker, he greatly advanced our understanding of polymer chemistry.

Advances in colorimetric biosensors of exosomes: novel approaches based on natural enzymes and nanozymes

Exosomes are 30-150 nm vesicles derived from diverse cell types, serving as one of the most important biomarkers for early diagnosis and prognosis of diseases. However, the conventional detection method for exosomes faces significant challenges, such as unsatisfactory sensitivity, complicated operation, and the requirement of complicated devices. In recent years, colorimetric exosome biosensors with a visual readout underwent rapid development due to the advances in natural enzyme-based assays and the integration of various types of nanozymes. These synthetic nanomaterials show unique physiochemical properties and catalytic abilities, enabling the construction of exosome colorimetric biosensors with novel principles. This review will illustrate the reaction mechanisms and properties of natural enzymes and nanozymes, followed by a detailed introduction of the recent advances in both types of enzyme-based colorimetric biosensors. A comparison between natural enzymes and nanozymes is made to provide insights into the research that improves the sensitivity and convenience of assays. Finally, the advantages, challenges, and future directions of enzymes as well as exosome colorimetric biosensors are highlighted, aiming at improving the overall performance from different approaches.

A new SERS quantitative analysis method for trace malathion with recognition and catalytic amplification difunctional MOFTb@Au@MIP nanoprobe

New multifunctional nanomaterial preparation and its application to trace pollutant analysis are interesting to peoples. Using terbium metal-organic framework loaded gold nanoparticles (MOFTb@Au) as the nanosubstrate and 3-aminopropyltriethoxysilane (APTES) as the functional monomer, a new bifunctional nanosurface molecularly imprinted polymer nanoprobe of MOFTb@Au@MIP with strongly recognition and catalytic amplification functions was prepared by the microwave sol-gel procedure. It was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier infrared spectroscopy (FTIR) and other techniques. The nanoprobe was found to specifically recognize malathion (MAL) and catalyze the L-cysteine (Cys)-HAuCl4 nanogold indicator reaction to amplify the molecular spectral signal. The gold nanoparticles (AuNPs) generated in the system show a strong surface-enhanced Raman scattering (SERS) effect, resonant Rayleigh scattering (RRS) peak and UV absorption (Abs) peak at 1615 cm-1, 370 nm and 520 nm, respectively. Based on this, a new SERS/RRS/Abs trimode method for the detection of MAL can be established. It has been applied to the analysis of cereal samples with satisfactory recoveries of 95.2-107.4% and precision of 3.76-9.06%.

Diblock and Triblock Copolymers as Nanostructured Precursors to Functional Nanoporous Materials: From Design to Application

Block copolymers have gained tremendous interest from the scientific community in the last two decades. These macromolecular architectures indeed constitute ideal nanostructured precursors for the generation of nanoporous materials meant for various high added value applications. The parallel emergence of controlled polymerization techniques has notably enabled to finely control their molecular features to confer them with unique structural and physicochemical properties, such as low dispersity values (Đ), well-defined volume fractions, and controlled functionality. The nanostructuration and ordering of diblock or triblock copolymers, which can be achieved through various experimental techniques, including channel die processing, solvent vapor or thermal annealing, nonsolvent-induced phase separation or concomitant self-assembly, and nonsolvent-induced phase separation, allows for the preparation of orientated microphase-separated copolymers whose morphology is dictated by three main factors, i.e., Flory-Huggins interaction parameter between constitutive blocks, volume fraction of the blocks, and polymerization degree. This review article provides an overview of the actual state of the art regarding the preparation of functional nanoporous materials from either diblock or triblock copolymers. It will also highlight the major applications of such peculiar materials.

Eco-Friendly UV-Spectrophotometric Methods Employing Magnetic Nano-Composite Polymer for the Extraction and Analysis of Sexual Boosters in Adulterated Food Products: Application of Computer-Aided Design

BACKGROUND

Solid phase extraction (SPE) techniques, based on computationally designed magnetic-based multi-targeting molecular imprinted polymer (MT-MIP), combined with UV spectrophotometric approaches provide advantages in the examination of counterfeit samples.

OBJECTIVE

The current work describes an innovative and sustainable methodology for the simultaneous determination of tadalafil (TAD) and dapoxetine hydrochloride (DAP) in aphrodisiac counterfeit products (honey and instant coffee) utilizing SPE exploiting MT-MIP. Additionally, an innovative UV spectrophotometric method capable of resolving TAD in its pharmaceutical binary mixtures with DAP was developed. A novel computational approach was implemented to tailor the synthesis and design of the MT-MIP particles.

METHODS

We applied a newly developed UV spectrophotometric method which was based on a Fourier self-deconvolution (FSD) method coupled with the isoabsorptive point for determination of TAD and DAP in pharmaceutical dosage form. We also applied an SPE process based on MT-MIP designed particles, assisting in the analysis of both drugs in counterfeit food samples. The SPE process and the UV spectroscopic methodology were assessed regarding their greenness using the pioneering green analytical procedure index (GAPI), analytical greeness including sample preparation (AGREEprep) and AGREE tools. The synthesized MT-MIP particles were characterized by scanning electron microscopy and energy-dispersive x-ray spectroscopy.

RESULTS

The suggested spectrophotometric methods revealed a wide linear concentration range of 2-50 µg/mL with lower LODs in the range of 0.604-0.994 µg/mL. Additionally, the suggested method demonstrated the utmost sensitivity and eco-friendliness for their target in its mixed dosage form and counterfeit food products.

CONCLUSION

The SPE process and the developed analytical UV spectroscopic methodology were validated as per the ICH guidelines, and were found to be suitable for overseeing some counterfeiting activities in commercially available honey and instant coffee aphrodisiac products.

HIGHLIGHTS

An SPE method based on MT-MIP magnetic-based polymer and a UV spectroscopic method were successfully developed for analysis of TAD and DAP in different matrices.

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.

Carbonic anhydrase mimics with rationally designed active sites for fine-tuned catalytic activity and selectivity in ester hydrolysis

Numerous hydrolytic enzymes utilize zinc as a cofactor for catalysis. We here report water-soluble polymeric nanoparticles with zinc ions in active sites and a nearby base as a mimic of carbonic anhydrase (CA). Their pKa of 6.3-6.4 for zinc-bound water is lower than the 6.8-7.3 value for natural enzymes, which allows the catalyst to hydrolyze nonactivated alkyl esters under neutral conditions-a long sought-after goal for artificial esterases. The size and shape of the active site can be rationally tuned through a template used in molecular imprinting. Subtle structural changes in the template, including shifting an ethyl group by one C-N bond and removal of a methylene group, correlate directly with catalytic activity. A catalyst can be made to be highly specific or have broad substrate specificity through modular synthesis of templates.

Imprinting of nanoparticles in thin films: Quo Vadis?

Nanomaterials, and especially nanoparticles, have been introduced to almost any aspect of our lives. This has caused increasing concern as to their toxicity and adverse effects on the environment and human health. The activity of nanoparticles, including their nanotoxicity, is not only a function of the material they are made of but also their size, shape, and surface properties. It is evident that there is an unmet need for simple approaches to the speciation of nanoparticles, namely to monitor and detect them based on their properties. An appealing method for such speciation involves the imprinting of nanoparticles in soft matrices. The principles of imprinting nanoparticles originate from the molecularly imprinted polymer (MIP) approach. This review summarizes the current status of this emerging field, which bridges between the traditional MIP approach and the imprinting of larger entities such as viruses and bacteria. The concepts of nanoparticle imprinting and the requirement of both physical and chemical matching between the nanoparticles and the matrix are discussed and demonstrated.

Proteolytic polymer: polyacrylamides functionalized with amino acids cleave bovine and human serum albumins

Polyacrylamides with various compositions of serine, aspartic acid, and histidine, which are the amino acids involved in the catalytic triad of natural serine protease chymotrypsin, were synthesized and their protein cleavage activity was investigated. SDS-PAGE analysis showed that some of the synthesized ternary copolymers showed cleavage activity against bovine and human serum albumins. Polyacrylamides incorporating a single type of amino acid were also able to cleave the protein substrates. These homopolymers exhibited unique cleavage profiles and pH and temperature sensitivities that differed from those of α-chymotrypsin. The results indicate the potential of polymers functionalized with amino acids as proteolytic artificial enzymes.

Imprinted Hydrogel Nanoparticles for Protein Biosensing: A Review

Over the past decade, molecular imprinting (MI) technology has made tremendous progress, and the advancements in nanotechnology have been the major driving force behind the improvement of MI technology. The preparation of nanoscale imprinted materials, i.e., molecularly imprinted polymer nanoparticles (MIP NPs, also commonly called nanoMIPs), opened new horizons in terms of practical applications, including in the field of sensors. Currently, hydrogels are very promising for applications in bioanalytical assays and sensors due to their high biocompatibility and possibility to tune chemical composition, size (microgels, nanogels, etc.), and format (nanostructures, MIP film, fibers, etc.) to prepare optimized analyte-responsive imprinted materials. This review aims to highlight the recent progress on the use of hydrogel MIP NPs for biosensing purposes over the past decade, mainly focusing on their incorporation on sensing devices for detection of a fundamental class of biomolecules, the peptides and proteins. The review begins by directing its focus on the ability of MIPs to replace biological antibodies in (bio)analytical assays and highlight their great potential to face the current demands of chemical sensing in several fields, such as disease diagnosis, food safety, environmental monitoring, among others. After that, we address the general advantages of nanosized MIPs over macro/micro-MIP materials, such as higher affinity toward target analytes and improved binding kinetics. Then, we provide a general overview on hydrogel properties and their great advantages for applications in the field of Sensors, followed by a brief description on current popular routes for synthesis of imprinted hydrogel nanospheres targeting large biomolecules, namely precipitation polymerization and solid-phase synthesis, along with fruitful combination with epitope imprinting as reliable approaches for developing optimized protein-imprinted materials. In the second part of the review, we have provided the state of the art on the application of MIP nanogels for screening macromolecules with sensors having different transduction modes (optical, electrochemical, thermal, etc.) and design formats for single use, reusable, continuous monitoring, and even multiple analyte detection in specialized laboratories or in situ using mobile technology. Finally, we explore aspects about the development of this technology and its applications and discuss areas of future growth.

Supramolecular Peptide Nanostructures Regulate Catalytic Efficiency and Selectivity

We report three constitutionally isomeric tetrapeptides, each comprising one glutamic acid (E) residue, one histidine (H) residue, and two lysine (KS ) residues functionalized with side-chain hydrophobic S-aroylthiooxime (SATO) groups. Depending on the order of amino acids, these amphiphilic peptides self-assembled in aqueous solution into different nanostructures:nanoribbons, a mixture of nanotoroids and nanoribbons, or nanocoils. Each nanostructure catalyzed hydrolysis of a model substrate, with the nanocoils exhibiting the greatest rate enhancement and the highest enzymatic efficiency. Coarse-grained molecular dynamics simulations, analyzed with unsupervised machine learning, revealed clusters of H residues in hydrophobic pockets along the outer edge of the nanocoils, providing insight for the observed catalytic rate enhancement. Finally, all three supramolecular nanostructures catalyzed hydrolysis of the l-substrate only when a pair of enantiomeric Boc-l/d-Phe-ONp substrates were tested. This study highlights how subtle molecular-level changes can influence supramolecular nanostructures, and ultimately affect catalytic efficiency.

Molecularly Imprinted Polymer-Based Sensors for the Detection of Skeletal- and Cardiac-Muscle-Related Analytes

Molecularly imprinted polymers (MIPs) are synthetic polymers with specific binding sites that present high affinity and spatial and chemical complementarities to a targeted analyte. They mimic the molecular recognition seen naturally in the antibody/antigen complementarity. Because of their specificity, MIPs can be included in sensors as a recognition element coupled to a transducer part that converts the interaction of MIP/analyte into a quantifiable signal. Such sensors have important applications in the biomedical field in diagnosis and drug discovery, and are a necessary complement of tissue engineering for analyzing the functionalities of the engineered tissues. Therefore, in this review, we provide an overview of MIP sensors that have been used for the detection of skeletal- and cardiac-muscle-related analytes. We organized this review by targeted analytes in alphabetical order. Thus, after an introduction to the fabrication of MIPs, we highlight different types of MIP sensors with an emphasis on recent works and show their great diversity, their fabrication, their linear range for a given analyte, their limit of detection (LOD), specificity, and reproducibility. We conclude the review with future developments and perspectives.

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.

Artificial Esterase for Cooperative Catalysis of Ester Hydrolysis at pH 7

Ester is one of the most prevalent functional groups in natural and man-made products. Natural esterases hydrolyze nonactivated alkyl esters readily but artificial esterases generally use highly activated p-nitrophenyl esters as substrates. We report synthetic esterases constructed through molecular imprinting in cross-linked micelles. The water-soluble nanoparticle catalysts contain a thiouronium cation to mimic the oxyanion hole and a nearby base to assist the hydrolysis. Whereas this catalytic motif readily affords large rate acceleration for the hydrolysis of p-nitrophenyl hexanoate, nonactivated cyclopentyl hexanoate demands catalytic groups that can generate a strong nucleophile (hydroxide) in the active site. The hydroxide is stabilized by the protonated base when the external solution is at pH 7, enabling the hydrolysis of activated and nonactivated esters under neutral conditions.

Hierarchically Structured Molecularly Imprinted Nanotransducers for Truncated HER2-Targeted Photodynamic Therapy of Therapeutic Antibody-Resistant Breast Cancer

Antibodies have been a mainstream class of therapeutics for clinical treatment of various diseases, especially cancers. However, mutation in cancer cells leads to resistance to therapeutic antibodies, hyperactivity of proliferation of cancer cells, and difficulty in the development of therapeutic antibodies. Herein, we present a strategy termed molecularly imprinted nanotransducer (MINT) for targeted photodynamic therapy (PDT) of mutated cancers. The MINT is a rationally engineered nanocomposite featuring a core of an upconversion nanoparticle, a shell of a thin layer of molecularly imprinted polymer, and a photosensitizer modified on the surface. As a proof-of-principle, truncated HER2 (P95HER2) overexpressed breast cancer, a challenging cancer lacking effective targeted therapeutics, was used as the cancer model. The designed structure, properties, functions, and anticancer efficacy of MINT were systematically investigated and experimentally confirmed. The MINT could not only specifically target P95HER2+ cancer cells in vitro and in vivo but also efficiently transfer the irradiated light and generate excited-state oxygen, resulting in efficient targeted cancer killing. Therefore, the MINT strategy provides a promising therapeutic for targeted PDT of drug-resistant cancers caused by target mutation.

A novel bifunctional molecularly imprinted polymer-based SERS/RRS dimode nanosensor for ultratrace acetamiprid

A new acetamiprid (AP) molecularly imprinted polymer (MIP) nanosol was synthesized with α-methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinker and 2,2'-azobisisobutyronitrile as initiator, under the microwave irradiation. It was characterized by transmission electron microscopy, specific surface area and pore size analysis, and molecular spectroscopy. The bifunctional MIP nanomaterial not only had the recognition of AP but also had a strong catalysis of the nanogold dimode indicator reaction of chloroauric acid-dopamine. The generated gold nanoparticles (AuNPs) had strong surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects, and the two kinds of signals enhanced linearly with imprinted molecule AP increasing. Accordingly, a novel SERS/RRS nanosensor platform was constructed to detect 0.25-20 pmol/L and 0.5-50 pmol/L AP by SERS and RRS monitoring respectively. Moreover, a reliable nanocatalytic mechanism was proposed.

Engineering the Hydrophobic Microenvironment in Polystyrene-Supported Artificial Catalytic Triad Nanocatalysts: An Effective Strategy for Improving Catalytic Performance

Hydrophobic environments have been identified as one of the main parameters affecting the catalytic performance of artificial catalytic triads but are often ignored as an approach to engineering these catalysts. Here, we have developed a simple yet powerful strategy to engineer the hydrophobic environment in polystyrene-supported artificial catalytic triad (PSACT) nanocatalysts. Hydrophobic copolymers containing either oligo(ethylene glycol) side chains or hydrocarbon side chains were synthesized and used for the preparation of nanocatalysts through nanoprecipitation in aqueous media. By using the hydrolysis of 4-nitrophenyl acetate (4NA) as a model reaction, we studied the influence of chemical structures and effective constituent ratios of hydrophobic copolymers on the catalytic performance of PSACT nanocatalysts. Additionally, PSACT nanocatalysts could catalyze the hydrolysis of a few carboxylic esters, even polymers, and be reused for five consecutive runs without significant loss of catalytic activity. This strategy may open an avenue for engineering other artificial enzymes, and these PSACT nanocatalysts have potential applications for the hydrolysis of carboxylic esters.

Nanoparticle Scanners for the Identification of Key Sequences Involved in the Assembly and Disassembly of β-Amyloid Peptides

The aggregation of β-amyloid peptides (Aβ), implied in the development and progression of Alzheimer's disease, is driven by a complex set of intramolecular and intermolecular interactions involving both hydrophobic and polar residues. The key residues responsible for the forward assembling process may be different from those that should be targeted to disassemble already formed aggregates. Molecularly imprinted nanoparticle (MINP) receptors are reported in this work to strongly and selectively bind specific segments of Aβ₄₀. Combined fluorescence spectroscopy, atomic force microscopy (AFM) imaging, and circular dichroism (CD) spectroscopy indicate that binding residues 21-30 near the loop region is most effective at inhibiting the aggregation of monomeric Aβ₄₀, but residues 11-20 that include the internal β strand closer to the N-terminal represent the best target for disaggregating already formed aggregates in the polymerization phase. Once the aggregation proceeds to the saturation phase, binding residues 1-10 has the largest effect on the disaggregation, likely because of the accessibility of these amino acids relative to others to the MINP receptors.

Molecularly Imprinted Polymer-Based Sensors for Protein Detection

The accurate detection of biological substances such as proteins has always been a hot topic in scientific research. Biomimetic sensors seek to imitate sensitive and selective mechanisms of biological systems and integrate these traits into applicable sensing platforms. Molecular imprinting technology has been extensively practiced in many domains, where it can produce various molecular recognition materials with specific recognition capabilities. Molecularly imprinted polymers (MIPs), dubbed plastic antibodies, are artificial receptors with high-affinity binding sites for a particular molecule or compound. MIPs for protein recognition are expected to have high affinity via numerous interactions between polymer matrices and multiple functional groups of the target protein. This critical review briefly describes recent advances in the synthesis, characterization, and application of MIP-based sensor platforms used to detect proteins.

Magnetic Molecularly Imprinted Polymers for the Separation and Enrichment of Cannabidiol from Hemp Leaf Samples

Cannabidiol (CBD) has attracted immense attention due to its excellent clinical effects in the treatment of various diseases. However, rapid and accurate extraction of CBD from hemp plant concentrates remains a challenge. Thus, novel magnetic molecularly imprinted polymers (CBD-MMIPs) with specific recognizing capability for CBD were synthesized using ethylene glycol dimethacrylate as the cross-linker, CBD as the template, methacrylic acid as the functional monomer, azobisisobutyronitrile as the initiator, and Fe₃O₄ nanoparticles modified with SiO₂ as the magnetic carrier. The morphological, magnetic, and adsorption properties of obtained CBD-MMIPs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, surface area and porosity analyses, and various adsorption experiments. The results showed that the CBD-MMIPs had selective specificity and high adsorption capacity for CBD. The adsorption of CBD by CBD-MMIPs could reach equilibrium in a short time (30 min), and the maximum adsorption capacity was as high as 26.51 mg/g. The specific recognition and selectivity properties of CBD-MMIPs to CBD were significantly higher than that of other structural analogues, and the regeneration tests established that the CBD-MMIPs had good recyclability. Furthermore, the CBD-MMIPs could be successfully used as an adsorbent to the extraction of CBD from hemp leaf sample concentrates with high recovery efficiencies (93.46-97.40%).

Synthetic receptors in medicine

Cellular signaling is controlled by ligand receptor interaction and subsequent biochemical changes inside the cell. Manipulating receptors as per need that can be a strategy to alter the disease pathologies in various conditions. With recent advances in synthetic biology, now it is possible to engineer the artificial receptor "synthetic receptors." Synthetic receptors are the engineering receptors that have potential to alter the disease pathology by altering/manipulating the cellular signaling. Several synthetic receptors are being engineered that have shown positive regulation in several disease conditions. Thus, synthetic receptor-based strategy opens a new avenue in the medical field to cope up with various health issues. The current chapter summarizes updated information about the synthetic receptors and their applications in the medical field.

Metal-Organic Frameworks Meet Molecularly Imprinted Polymers: Insights and Prospects for Sensor Applications

The use of porous materials as the core for synthesizing molecularly imprinted polymers (MIPs) adds significant value to the resulting sensing system. This review covers in detail the current progress and achievements regarding the synergistic combination of MIPs and porous materials, namely metal/covalent-organic frameworks (MOFs/COFs), including the application of such frameworks in the development of upgraded sensor platforms. The different processes involved in the synthesis of MOF/COF-MIPs are outlined, along with their intrinsic properties. Special attention is paid to debriefing the impact of the morphological changes that occur through the synergistic combination compared to those that occur due to the individual entities. Thereafter, the strategies used for building the sensors, as well as the transduction modes, are overviewed and discussed. This is followed by a full description of research advances for various types of MOF/COF-MIP-based (bio)sensors and their applications in the fields of environmental monitoring, food safety, and pharmaceutical analysis. Finally, the challenges/drawbacks, as well as the prospects of this research field, are discussed in detail.

A review of the modern principles and applications of solid-phase extraction techniques in chromatographic analysis

Analytical processes involving sample preparation, separation, and quantifying analytes in complex mixtures are indispensable in modern-day analysis. Each step is crucial to enriching correct and informative results. Therefore, sample preparation is the critical factor that determines both the accuracy and the time consumption of a sample analysis process. Recently, several promising sample preparation approaches have been made available with environmentally friendly technologies with high performance. As a result of its many advantages, solid-phase extraction (SPE) is practiced in many different fields in addition to the traditional methods. The SPE is an alternative method to liquid–liquid extraction (LLE), which eliminates several disadvantages, including many organic solvents, a lengthy operation time and numerous steps, potential sources of error, and high costs. SPE advanced sorbent technology reorients with various functions depending on the structure of extraction sorbents, including reversed-phase, normal-phase, cation exchange, anion exchange, and mixed-mode. In addition, the commercial SPE systems are disposable. Still, with the continual developments, the restricted access materials (RAM) and molecular imprinted polymers (MIP) are fabricated to be active reusable extraction cartridges. This review will discuss all the theoretical and practical principles of the SPE techniques, focusing on packing materials, different forms, and performing factors in recent and future advances. The information about novel methodological and instrumental solutions in relation to different variants of SPE techniques, solid-phase microextraction (SPME), in-tube solid-phase microextraction (IT-SPME), and magnetic solid-phase extraction (MSPE) is presented. The integration of SPE with analytical chromatographic techniques such as LC and GC is also indicated. Furthermore, the applications of these techniques are discussed in detail along with their advantages in analyzing pharmaceuticals, biological samples, natural compounds, pesticides, and environmental pollutants, as well as foods and beverages.

Synergistic Hydrolysis of Cellulose by a Blend of Cellulase-Mimicking Polymeric Nanoparticle Catalysts

Enzyme-like catalysts by design have been a long sought-after goal of chemists but difficult to realize due to the challenges in the construction of multifunctionalized active sites with accurately positioned catalytic groups for complex substrates. Hydrolysis of cellulose is a key step in biomass utilization and requires multiple enzymes to work in concert to overcome the difficulty associated with hydrolyzing the recalcitrant substrate. We here report methods to construct synthetic versions of these enzymes through covalent molecular imprinting and strategic postmodification of the imprinted sites. The synthetic catalysts cleave a cellulose chain endolytically at multiple positions or exolytically from the nonreducing end by one or three glucose units at a time, all using the dicarboxylic acid motif found in natural cellulases. By mimicking the endocellulase, exocellulase, and β-glucosidase, the synthetic catalysts hydrolyze cellulose in a synergistic manner, with an activity at 90 °C in pH 6.5 buffer more than doubled that of Aspergillus niger cellulase at pH 5 and 37 °C and 44% of that of a commercial cellulase blend (from Novozyme). As robust cross-linked polymeric nanoparticles, the synthetic catalysts showed little changes in activity after preheating at 90 °C for 3 days and could be reused, maintaining 76% of activity after 10 reaction cycles.

Molecularly imprinted materials for glycan recognition and processing

Carbohydrates are the most abundant organic molecules on Earth and glycosylation is the most common posttranslational modification of proteins. Glycans are involved in a plethora of biological processes including cell adhesion, bacterial and viral infection, inflammation, and cancer development. Coincidently, glycosides were some of the earliest molecules imprinted and have been instrumental in the development of covalent molecular imprinting technology. This perspective illustrates recently developed molecularly imprinted materials for glycan binding and processing. Novel imprinting techniques and postmodification led to development of synthetic glycan-binding materials capable of competing with natural lectins in affinity and artificial glycosidases for selective hydrolysis of complex glycans. These materials are expected to significantly advance glycochemistry, glycobiology, and related areas such as biomass conversion.

Controlling enzyme reactions by supramolecular protection and deprotection of oligosaccharide substrates

Protection/deprotection is a powerful strategy in the total synthesis of complex organic molecules but similar tools are nearly absent in enzymatic reactions. We here report supramolecular protective receptors that outcompete an enzyme in the binding of oligosaccharides. The strong binding inhibits the enzymatic reaction and addition of an even stronger ligand for the receptor releases the substrate. These receptors could be used to control products from the same substrate/enzyme mixture and regulate enzymatic reactions reversibly.

Imprinted Polymeric Nanoparticles as Artificial Enzymes for Ester Hydrolysis at Room Temperature and pH 7

Natural esterases hydrolyze esters under physiological pHs but chemists often have to use strongly acidic or basic conditions for the same hydrolysis. We report synthetic nanoparticle catalysts that hydrolyze nonactivated alkyl esters at room temperature and neutral pH, with enzyme-like catalytic mechanisms and exquisite substrate selectivity. Unlike natural enzymes that denature easily at elevated temperatures, the synthetic catalysts become more active at higher temperatures.

Optimization of Nanosubstrates toward Molecularly Surface-Functionalized Raman Spectroscopy

Diagnostic advancements require continuous developments of reliable analytical sensors, which can simultaneously fulfill many criteria, including high sensitivity and specificity for a broad range of target analytes. Incorporating the highly sensitive attributes of surface-enhanced Raman spectroscopy (SERS) combined with highly specific analyte recognition capabilities via molecular surface functionalization could address major challenges in molecular diagnostics and analytical spectroscopy fields. Herein, we have established a controllable molecular surface functionalization process for a series of textured gold surfaces. To create the molecularly surface-functionalized SERS platforms, self-assembled benzyl-terminated and benzoboroxole-terminated monolayers were used to compare which thicknesses and root-mean-square (RMS) roughness of planar gold produced the most sensitive and specific surfaces. Optimal functionalization was identified at 80 ± 8 nm thickness and 7.2 ± 1.0 nm RMS. These exhibited a considerably higher SERS signal (70-fold) and improved sensitivity for polysaccharides when analyzed using principal component analysis (PCA) and self-organizing maps (SOM). These findings lay the procedure for establishing the optimal substrate specifications as an essential prerequisite for future studies aiming at developing the feasibility of molecular imprinting for SERS diagnostic applications and the subsequent delivery of advanced, highly selective, and sensitive sensing devices and analytical platforms.

Pulsed-sonochemiluminescence combined with molecularly imprinted polymerized high internal phase emulsion adsorbent for determination of bentazone

A small low-power humidifier with a simple programmable on/off switch was used as a pulsed ultrasound generator. Using this tool, a novel sonochemiluminescence (SCL) method was developed to determine bentazone. To the best of our knowledge, no chemiluminescence method has been proposed to determine this pesticide. Only five studies have been proposed for SCL quantitative applications so far. Therefore, revealing new aspects of SCL promises to develop analytical methods for the quantitative determination of different substances. A molecularly imprinted polymerized high internal phase emulsion (MIP-polyHIPE) was synthesized, bentazone separated from aqueous solutions, and pre-concentrated by the MIP-polyHIPE foam. The adsorption of bentazone on the MIP-polyHIPE adsorbent was theoretically studied by density functional theory through molecular dynamics simulation. Both experimental and simulation results indicated removal and pre-concentration of bentazone by the MIP-polyHIPE adsorbent. Using the proposed SCL method and without pre-concentration process, a linear dynamic range (LDR) of 2.5 × 10^-7-5.0 × 10^-5 mol L^-1 and a limit of detection (LOD) of 8.4 × 10^-8 mol L^-1 were obtained for bentazone with a relative standard deviation of 2.64%. The LDR and LOD were improved to 2.6 × 10^-9-2.0 × 10^-7 mol L^-1 and 8.8 × 10^-10 mol L^-1, respectively, using MIP-polyHIPE adsorbents. The method's application was evaluated by removing and pre-concentration of bentazone from water samples, including well, river, and tap water. The results showed that the pre-concentration factor and recovery percentages were 113-131 times and 93-106%, respectively, using the MIP-polyHIPE absorbent.

Synthesis of an Organotin Specific Molecularly Imprinted Polymer for Organotin Passive Sampling in Seawater

Environmental contaminations can sometimes be difficult to measure, particularly in complex matrices such as seawater. This is the case of organotin compounds (OSn) such as the monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT), whose range of polarity is wide. These compounds, mostly coming from antifouling paints used on ship shell, can be found in water and sediments where they are stable and can persist for years. Passive sampling is gaining in interest to offer solutions to monitor these kinds of compounds even in low concentrations. However, due to the diversity of pollutants present in the environment nowadays, it is important to propose solutions that allow a specific sampling. This work aims to highlight the usability of molecularly imprinted polymers (MIPs) in passive sampling for the monitoring of OSn. MIPs were synthetized using three synthesis ways (bulk, suspension, and mini-emulsion processes) and kinetics were realized in order to estimate the retention of OSn by the solid MIP phase. Results highlighted a good retention of OSn with mean retention kinetic constants near 10−5, 10−6 and 10−7 L·ng·s−1 for DBT, TBT and MBT respectively. The synthesis mode showed no impact on retention kinetics, therefore, bulk synthesis is recommended because of its simplicity. If the elimination of OSn from MIPs is to be optimized, the retention of OSn on MIPs has been demonstrated, and is very promising for their use in specific passive samplers.

In vivo stealthified molecularly imprinted polymer nanogels incorporated with gold nanoparticles for radiation therapy

Radiation therapy is a representative therapeutic approach for cancer treatment, wherein the development of efficient radiation sensitizers with low side effects is critical. In this study, a novel stealth radiation sensitizer based on Au-embedded molecularly imprinted polymer nanogels (Au MIP-NGs) was developed for low-dose X-ray radiation therapy. Surface plasmon resonance measurements reveal the good affinity and selectivity of the obtained Au MIP-NGs toward the target dysopsonic protein, human serum albumin. The protein recognition capability of the nanogels led to the formation of the albumin-rich protein corona in the plasma. The Au MIP-NGs acquire stealth capability in vivo through protein corona regulation using the intrinsic dysopsonic proteins. The injection of Au MIP-NGs improved the efficiency of the radiation therapy in mouse models of pancreatic cancer. The growth of the pancreatic tumor was inhibited even at low X-ray doses (2 Gy). The novel strategy reported in this study for the synthesis of stealth nanomaterials based on nanomaterial-protein interaction control shows significant potential for application even in other approaches for cancer treatment, diagnostics, and theranostics. This strategy paves a way for the development of a wide range of effective nanomedicines for cancer therapy.