Plastic antibodies: developments and applications

Surface-enhanced Raman sensor with molecularly imprinted nanoparticles as highly sensitive recognition material for cancer marker amino acids

Surface-enhanced Raman scattering (SERS) is a powerful technique primarily due to its high sensitivity and signal-enhancing properties, which enable the identification of unique vibrational fingerprints. These fingerprints can be used for the diagnosis and monitoring of diseases such as cancer. It is crucial to selectively identify cancer biomarkers for early diagnosis. A correlation has been established between the reduction in the concentration of specific amino acids and the stage of the disease, particularly tryptophan (TPP) and tyrosine (TRS) in individuals diagnosed with prostate cancer. In this work, we present a strategy to analyze TPP and TRS amino acids using molecularly imprinted polymer nanoparticles (nanoMIPs), which selectively detect target molecules in a SERS sensor. NanoMIPs are synthesized using the solid-phase molecular imprinting method with TPP and TRS as templates. These are then immobilized on a SERS substrate with gold nanoparticles to measure samples prepared from tryptophan and tyrosine in phosphate-buffered saline. The detection and quantification limits of the designed sensor are 7.13 μM and 23.75 μM for TPP, and 22.11 μM and 73.72 μM for TRS, respectively. Our study lays the groundwork for future investigations utilizing nanoMIPs in SERS assessments of TPP and TRS as potential biomarkers for prostate cancer detection.

Vapor-Phase Synthesis of Molecularly Imprinted Polymers on Nanostructured Materials at Room-Temperature

Molecularly imprinted polymers (MIPs) have recently emerged as robust and versatile artificial receptors. MIP synthesis is carried out in liquid phase and optimized on planar surfaces. Application of MIPs to nanostructured materials is challenging due to diffusion-limited transport of monomers within the nanomaterial recesses, especially when the aspect ratio is >10. Here, the room temperature vapor-phase synthesis of MIPs in nanostructured materials is reported. The vapor phase synthesis leverages a >1000-fold increase in the diffusion coefficient of monomers in vapor phase, compared to liquid phase, to relax diffusion-limited transport and enable the controlled synthesis of MIPs also in nanostructures with high aspect ratio. As proof-of-concept application, pyrrole is used as the functional monomer thanks to its large exploitation in MIP preparation; nanostructured porous silicon oxide (PSiO2 ) is chosen to assess the vapor-phase deposition of PPy-based MIP in nanostructures with aspect ratio >100; human hemoglobin (HHb) is selected as the target molecule for the preparation of a MIP-based PSiO2 optical sensor. High sensitivity and selectivity, low detection limit, high stability and reusability are achieved in label-free optical detection of HHb, also in human plasma and artificial serum. The proposed vapor-phase synthesis of MIPs is immediately transferable to other nanomaterials, transducers, and proteins.

Molecularly imprinted polymer-based optical immunosensors

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

New autonomous and self-signaling biosensing device for sarcosine detection

An early diagnosis is the gold standard for cancer survival. Biosensors have proven their effectiveness in monitoring cancer biomarkers but are still limited to a series of requirements. This work proposes an integrated power solution, with an autonomous and self-signaling biosensing device. The biorecognition element is produced in situ by molecular imprinting to detect sarcosine, a known biomarker for prostate cancer. The biosensor was assembled on the counter-electrode of a dye-sensitized solar cell (DSSC), simultaneously using EDOT and Pyrrole as monomers for the biomimetic process and the catalytic reduction of triiodide in the DSSC. After the rebinding assays, the hybrid DSSC/biosensor displayed a linear behavior when plotting the power conversion efficiency (PCE) and the charge transfer resistance (R_CT) against the logarithm of the concentration of sarcosine. The latter obtained a sensitivity of 0.468 Ω/decade of sarcosine concentration, with a linear range between 1 ng/mL and 10 μg/mL, and a limit of detection of 0.32 ng/mL. When interfacing an electrochromic cell, consisting of a PEDOT-based material, with the hybrid device, a color gradient between 1 ng/mL and 10 μg/mL of sarcosine was observed. Thus, the device can be used anywhere with access to a light source, completely equipment-free, suitable for point-of-care analysis and capable of detecting sarcosine within a range of clinical interest.

Rapid Screening and Synthesis of Abiotic Synthetic Receptors for Selective Bacterial Recognition

The major challenges that impede the preparation of abiotic synthetic receptors designed to feature selective bacterial recognition properties are the complexity, nonrobustness, and environmental adaptability of live microbes. Here, we describe a new rapid screening strategy to determine the optimal polymer formulation on 96-well plates and then produce abiotic synthetic receptors by imprinting the surface marker lipopolysaccharide (LPS) of Gram-negative bacteria. The resulting LPS-imprinted nanoparticles reveal remarkable affinity toward LPS with an equilibrium dissociation constant (K_D) value of 10^-12 M and can distinguish and selectively recognize specific bacteria in whole blood at concentrations down to 10 cells/mL. The incorporation of gold nanorods into imprinted nanoparticles allows selective microbial inactivation based on photothermal treatment. We have also demonstrated that the imprinted nanoparticles with high affinity for bacteria could induce bacteria clustering, drive the expression of quorum-sensing-controlled signal molecules, and eventually enhance the productivity of the cell factory.

Molecularly Imprinted Polymeric Particles Created Using Droplet-Based Microfluidics: Preparation and Applications

Recent years have witnessed increased attention to the use of droplet-based microfluidics as a tool for the fabrication of microparticles due to this method's ability to exploit fluid mechanics to create materials with a narrow range of sizes. In addition, this approach offers a controllable way to configure the composition of the resulting micro/nanomaterials. To date, molecularly imprinted polymers (MIPs) in particle form have been prepared using various polymerization methods for several applications in biology and chemistry. However, the traditional approach, that is, the production of microparticles through grinding and sieving, generally leads to poor control over particle size and distribution. Droplet-based microfluidics offers an attractive alternative for the fabrication of molecularly imprinted microparticles. This mini-review aims to present recent examples highlighting the application of droplet-based microfluidics to fabricate molecularly imprinted polymeric particles for applications in the chemical and biomedical sciences.

A Review on Bio- and Chemosensors for the Detection of Biogenic Amines in Food Safety Applications: The Status in 2022

This article provides an overview on the broad topic of biogenic amines (BAs) that are a persistent concern in the context of food quality and safety. They emerge mainly from the decomposition of amino acids in protein-rich food due to enzymes excreted by pathogenic bacteria that infect food under inappropriate storage conditions. While there are food authority regulations on the maximum allowed amounts of, e.g., histamine in fish, sensitive individuals can still suffer from medical conditions triggered by biogenic amines, and mass outbreaks of scombroid poisoning are reported regularly. We review first the classical techniques used for selective BA detection and quantification in analytical laboratories and focus then on sensor-based solutions aiming at on-site BA detection throughout the food chain. There are receptor-free chemosensors for BA detection and a vastly growing range of bio- and biomimetic sensors that employ receptors to enable selective molecular recognition. Regarding the receptors, we address enzymes, antibodies, molecularly imprinted polymers (MIPs), and aptamers as the most recent class of BA receptors. Furthermore, we address the underlying transducer technologies, including optical, electrochemical, mass-sensitive, and thermal-based sensing principles. The review concludes with an assessment on the persistent limitations of BA sensors, a technological forecast, and thoughts on short-term solutions.

Nano-molecularly imprinted polymers (nanoMIPs) as a novel approach to targeted drug delivery in nanomedicine

Molecularly imprinted polymers - MIPs - denote synthetic polymeric structures that selectively recognize the molecule of interest against which MIPs are templated. A number of works have demonstrated that MIPs can exceed the affinity and selectivity of natural antibodies, yet operating by the same principle of "lock and key". In contrast to antibodies, which have certain limitations related to the minimal size of the antigen, nanoMIPs can be fabricated against almost any target molecule irrespective of its size and low immunogenicity. Furthermore, the cost of MIP production is much lower compared to the cost of antibody production. Excitingly, MIPs can be used as nanocontainers for specific delivery of therapeutics both in vitro and in vivo. The adoption of the solid phase synthesis rendered MIPs precise reproducible characteristics and, as a consequence, improved the controlled release of therapeutic payloads. These major breakthroughs paved the way for applicability of MIPs in medicine as a novel class of therapeutics. In this review, we highlight recent advances in the fabrication of MIPs, mechanisms of controlled release from the MIPs, and their applicability in biomedical research.

Raman and Scanning Probe Microsocopy for differentiating surface imprints of E.coli and B.cereus

Molecularly imprinted polymers (MIPs) are artificial recognition materials mimicking biological recognition entities such as antibodies. The general model of imprinting assumes that functional monomers interact with functional groups present on...

Advanced biomedical hydrogels: molecular architecture and its impact on medical applications

Hydrogels are cross-linked polymeric networks swollen in water, physiological aqueous solutions or biological fluids. They are synthesized by a wide range of polymerization methods that allow for the introduction of linear and branched units with specific molecular characteristics. In addition, they can be tuned to exhibit desirable chemical characteristics including hydrophilicity or hydrophobicity. The synthesized hydrogels can be anionic, cationic, or amphiphilic and can contain multifunctional cross-links, junctions or tie points. Beyond these characteristics, hydrogels exhibit compatibility with biological systems, and can be synthesized to render systems that swell or collapse in response to external stimuli. This versatility and compatibility have led to better understanding of how the hydrogel's molecular architecture will affect their physicochemical, mechanical and biological properties. We present a critical summary of the main methods to synthesize hydrogels, which define their architecture, and advanced structural characteristics for macromolecular/biological applications.

The Selectivity of Immunoassays and of Biomimetic Binding Assays with Imprinted Polymers

Molecularly imprinted polymers have been shown to be useful in competitive biomimetic binding assays. Recent developments in materials science have further enhanced the capabilities of imprinted polymers. Binding assays, biological and biomimetic alike, owe their usefulness to their selectivity. The selectivity of competitive binding assays has been characterized with the cross-reactivity, which is usually expressed as the ratio of the measured IC50 concentration values of the interferent and the analyte, respectively. Yet this cross-reactivity is only a rough estimate of analytical selectivity. The relationship between cross-reactivity and analytical selectivity has apparently not been thoroughly investigated. The present work shows that this relationship depends on the underlying model of the competitive binding assay. For the simple but widely adopted model, where analyte and interferent compete for a single kind of binding site, we provide a simple formula for analytical selectivity. For reasons of an apparent mathematical problem, this formula had not been found before. We also show the relationship between analytical selectivity and cross-reactivity. Selectivity is also shown to depend on the directly measured quantity, e.g., the bound fraction of the tracer. For those cases where the one-site competitive model is not valid, a practical procedure is adopted to estimate the analytical selectivity. This procedure is then used to analyze the example of the competitive two-site binding model, which has been the main model for describing molecularly imprinted polymer behavior. The results of this work provide a solid foundation for assay development.

Ultrasensitive electrochemical molecularly imprinted sensor based on AuE/Ag-MOF@MC for determination of hemoglobin using response surface methodology

Considering the importance of determining the levels of hemoglobin (Hb) as a vital protein in red blood cells, in this work a highly sensitive electrochemical sensor was developed based on a gold electrode (AuE) modified with Ag metal-organic framework mesoporous carbon (Ag-MOF@MC) and molecularly imprinted polymers (MIPs). To that end, the MIP layer was formed on the Ag-MOF@MC by implanting Hb as the pattern molecule during the polymerization. The modified electrode was designed using electrochemical approaches including differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Using a response level experimental design method, the most important parameters affecting the reaction of the sensing system including pH, incubation time, and scanning rate were optimized. Following the same route, the Hb concentration, pH, temperature, and elution times were optimized to prepare the imprinted polymer layer on the Ag-MOF@MC surface. By exploiting DPV techniques based on the optimal parameters, the electrochemical response of the AuE/Ag-MOF@MC-MIPs for Hb determination was recorded in a wide linear dynamic range (LDR) of 0.2 pM to 1000 nM, with a limit of detection (LOD) of 0.09 pM. Moreover, the Ag-MOF@MC-MIP sensing system showed good stability, high selectivity, and acceptable reproducibility for Hb determination. The sensing system was successfully applied for Hb determination in real blood samples, and the results were compared with those of the standard methods for Hb determination. Acceptable recovery (99.0%) and RDS% (4.6%) confirmed the applicability and reliability of the designed Hb sensing system.

The Selectivity of Molecularly Imprinted Polymers

The general claim about novel molecularly imprinted polymers is that they are selective for their template or for another target compound. This claim is usually proved by some kind of experiment, in which a performance parameter of the imprinted polymer is shown to be better towards its template than towards interferents. A closer look at such experiments shows, however, that different experiments may differ substantially in what they tell about the same imprinted polymer's selectivity. Following a short general discussion of selectivity concepts, the selectivity of imprinted polymers is analyzed in batch adsorption, binding assays, chromatography, solid phase extraction, sensors, membranes, and catalysts. A number of examples show the problems arising with each type of application. Suggestions for practical method design are provided.

Molecularly Imprinted Polymer (MIP) Applications in Natural Product Studies Based on Medicinal Plant and Secondary Metabolite Analysis

Characterization and extraction of plant secondary metabolites are important in agriculture, pharmaceutical, and food industry. In this regard, the applied analytical methods are mostly costly and time-consuming; therefore, choosing a suitable approach is essential for optimum results and economic suitability. One of the recently considered methods used to characterize new types of materials is MIPs. Among the various applications of MIPs is the identification and separation of various plant-derived compounds, such as secondary metabolites, chemical residues, and pesticides. The present review describes the application of MIPs as a tool in medicinal plant material analysis, focusing on plant secondary metabolism.

A review of the incorporation of QDs and imprinting technology in optical sensors – imprinting methods and sensing responses

This review aims to cover the simultaneous method of using molecularly imprinted technology and quantum dots (QDs) as well as its application in the field of optical sensors.

Molecularly Imprinted Polymers: Antibody Mimics for Bioimaging and Therapy

Molecularly imprinted polymers (MIPs) are tailor-made chemical receptors that recognize and bind target molecules with a high affinity and selectivity. MIPs came into the spotlight in 1993 when they were dubbed "antibody mimics," and ever since, they have been widely studied for the extraction or trapping of chemical pollutants, in immunoassays, and for the design of sensors. Owing to novel synthesis strategies resulting in more biocompatible MIPs in the form of soluble nanogels, these synthetic antibodies have found favor in the biomedical domain since 2010, when for the first time, they were shown to capture and eliminate a toxin in live mice. This review, covering the years 2015-2020, will first describe the rationale behind these antibody mimics, and the different synthesis methods that have been employed for the preparation of MIPs destined for in vitro and in vivo targeting and bioimaging of cancer biomarkers, an emerging and fast-growing area of MIP applications. MIPs have been synthesized for targeting and visualizing glycans and protein-based cell receptors overexpressed in certain diseases, which are well-known biomarkers for example for tumors. When loaded with drugs, the MIPs could locally kill the tumor cells, making them efficient therapeutic agents. We will end the review by reporting how MIPs themselves can act as therapeutics by inhibiting cancer growth. These works mark a new opening in the use of MIPs for antibody therapy and even immunotherapy, as materials of the future in nanomedicine.

Key Enabling Technologies for Point-of-Care Diagnostics

A major trend in biomedical engineering is the development of reliable, self-contained point-of-care (POC) devices for diagnostics and in-field assays. The new generation of such platforms increasingly addresses the clinical and environmental needs. Moreover, they are becoming more and more integrated with everyday objects, such as smartphones, and their spread among unskilled common people, has the power to improve the quality of life, both in the developed world and in low-resource settings. The future success of these tools will depend on the integration of the relevant key enabling technologies on an industrial scale (microfluidics with microelectronics, highly sensitive detection methods and low-cost materials for easy-to-use tools). Here, recent advances and perspectives will be reviewed across the large spectrum of their applications.

Molecular LEGO by domain-imprinting of cytochrome P450 BM3

HYPOTHESIS

Electrosynthesis of the MIP nano-film after binding of the separated domains or holo-cytochrome BM3 via an engineered anchor should result in domain-specific cavities in the polymer layer.

EXPERIMENTS

Both the two domains and the holo P450 BM3 have been bound prior polymer deposition via a N-terminal engineered his6-anchor to the electrode surface. Each step of MIP preparation was characterized by cyclic voltammetry of the redox-marker ferricyanide. Rebinding after template removal was evaluated by quantifying the suppression of the diffusive permeability of the signal for ferricyanide and by the NADH-dependent reduction of cytochrome c by the reductase domain (BMR).

FINDINGS

The working hypothesis is verified by the discrimination of the two domains by the respective MIPs: The holoenzyme P450 BM3 was ca. 5.5 times more effectively recognized by the film imprinted with the oxidase domain (BMO) as compared to the BMR-MIP or the non-imprinted polymer (NIP). Obviously, a cavity is formed during the imprinting process around the his₆-tag-anchored BMR which cannot accommodate the broader BMO or the P450 BM3. The affinity of the MIP towards P450 BM3 is comparable with that to the monomer in solution. The his₆-tagged P450 BM3 binds (30 percent) stronger which shows the additive effect of the interaction with the MIP and the binding to the electrode.

Imprinting Technology in Electrochemical Biomimetic Sensors

Biosensors are a promising tool offering the possibility of low cost and fast analytical screening in point-of-care diagnostics and for on-site detection in the field. Most biosensors in routine use ensure their selectivity/specificity by including natural receptors as biorecognition element. These materials are however too expensive and hard to obtain for every biochemical molecule of interest in environmental and clinical practice. Molecularly imprinted polymers have emerged through time as an alternative to natural antibodies in biosensors. In theory, these materials are stable and robust, presenting much higher capacity to resist to harsher conditions of pH, temperature, pressure or organic solvents. In addition, these synthetic materials are much cheaper than their natural counterparts while offering equivalent affinity and sensitivity in the molecular recognition of the target analyte. Imprinting technology and biosensors have met quite recently, relying mostly on electrochemical detection and enabling a direct reading of different analytes, while promoting significant advances in various fields of use. Thus, this review encompasses such developments and describes a general overview for building promising biomimetic materials as biorecognition elements in electrochemical sensors. It includes different molecular imprinting strategies such as the choice of polymer material, imprinting methodology and assembly on the transduction platform. Their interface with the most recent nanostructured supports acting as standard conductive materials within electrochemical biomimetic sensors is pointed out.

Analytical Protein Microarrays: Advancements Towards Clinical Applications

Protein microarrays represent a powerful technology with the potential to serve as tools for the detection of a broad range of analytes in numerous applications such as diagnostics, drug development, food safety, and environmental monitoring. Key features of analytical protein microarrays include high throughput and relatively low costs due to minimal reagent consumption, multiplexing, fast kinetics and hence measurements, and the possibility of functional integration. So far, especially fundamental studies in molecular and cell biology have been conducted using protein microarrays, while the potential for clinical, notably point-of-care applications is not yet fully utilized. The question arises what features have to be implemented and what improvements have to be made in order to fully exploit the technology. In the past we have identified various obstacles that have to be overcome in order to promote protein microarray technology in the diagnostic field. Issues that need significant improvement to make the technology more attractive for the diagnostic market are for instance: too low sensitivity and deficiency in reproducibility, inadequate analysis time, lack of high-quality antibodies and validated reagents, lack of automation and portable instruments, and cost of instruments necessary for chip production and read-out. The scope of the paper at hand is to review approaches to solve these problems.

Preparation and catalytic performance of a molecularly imprinted Pd complex catalyst for Suzuki cross-coupling reactions

A molecularly imprinted Pd complex catalyst was successfully designed and prepared on a SiO₂ surface for shape-selective Suzuki cross-coupling reaction.

Molecularly Imprinted Membranes: Past, Present, and Future

More than 80 years ago, artificial materials with molecular recognition sites emerged. The application of molecular imprinting to membrane separation has been studied since 1962. Especially after 1990, such research has been intensively conducted by membranologists and molecular imprinters to understand the advantages of each technique with the aim of constructing an ideal membrane, which is still an active area of research. The present review aims to be a substantial, comprehensive, authoritative, critical, and general-interest review, placed at the cross section of two broad, interconnected, practical, and extremely dynamic fields, namely, the fields of membrane separation and molecularly imprinted polymers. This review describes the recent discoveries that appeared after repeated and fertile collisions between these two fields in the past three years, to which are added the worthy acknowledgments of pioneering discoveries and a look into the future of molecularly imprinted membranes. The review begins with a general introduction in membrane separation, followed by a short theoretical section regarding the basic principles of mass transport through a membrane. Following these general aspects on membrane separation, two principles of obtaining polymeric materials with molecular recognition properties are reviewed, namely, molecular imprinting and alternative molecular imprinting, followed the methods of obtaining and practical applications for the particular case of molecularly imprinted membranes. The review continues with insights into molecularly imprinted nanofiber membranes as a promising, highly optimized type of membrane that could provide a relatively high throughput without a simultaneous unwanted reduction in permselectivity. Finally, potential applications of molecularly imprinted membranes in a variety of fields are highlighted, and a look into the future of membrane separations is offered.

Fluorescent molecularly imprinted polymers as plastic antibodies for selective labeling and imaging of hyaluronan and sialic acid on fixed and living cells

Altered glycosylation levels or distribution of sialic acids (SA) or hyaluronan in animal cells are indicators of pathological conditions like infection or malignancy. We applied fluorescently-labeled molecularly imprinted polymer (MIP) particles for bioimaging of fixed and living human keratinocytes, to localize hyaluronan and sialylation sites. MIPs were prepared with the templates D-glucuronic acid (GlcA), a substructure of hyaluronan, and N-acetylneuraminic acid (NANA), the most common member of SA. Both MIPs were found to be highly selective towards their target monosaccharides, as no cross-reactivity was observed with other sugars like N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, D-glucose and D-galactose, present on the cell surface. The dye rhodamine and two InP/ZnS quantum dots (QDs) emitting in the green and in the red regions were used as fluorescent probes. Rhodamine-MIPGlcA and rhodamine-MIPNANA were synthesized as monodispersed 400nm sized particles and were found to bind selectively their targets located in the extracellular region, as imaged by epifluorescence and confocal microscopy. In contrast, when MIP-GlcA and MIP-NANA particles with a smaller size (125nm) were used, the MIPs being synthesized as thin shells around green and red emitting QDs respectively, it was possible to stain the intracellular and pericellular regions as well. In addition, simultaneous dual-color imaging with the two different colored QDs-MIPs was demonstrated. Importantly, the MIPs were not cytotoxic and did not affect cell viability; neither was the cells morphology affected as demonstrated by live cell imaging. These synthetic receptors could offer a new and promising imaging tool to monitor disease progression.

Analytical applications of MIPs in diagnostic assays: future perspectives

Many efforts have been made to produce artificial materials with biomimetic properties for applications in binding assays. Among these efforts, the technique of molecular imprinting has received much attention because of the high selectivity obtainable for molecules of interest, robustness of the produced polymers, simple and short synthesis, and excellent cost efficiency. In this review, progress in the field of molecularly imprinted sorbent assays is discussed-with a focus on work conducted from 2005 to date.

Recognition and selective adsorption of pesticides by superparamagnetic molecularly imprinted polymer nanospheres

Selective adsorption of pesticides phosalone, diazinon, and chlorpyrifos from aqueous solution by superparamagnetic molecularly imprinted polymer nanosphere.

Blood Group Typing: From Classical Strategies to the Application of Synthetic Antibodies Generated by Molecular Imprinting

Blood transfusion requires a mandatory cross-match test to examine the compatibility between donor and recipient blood groups. Generally, in all cross-match tests, a specific chemical reaction of antibodies with erythrocyte antigens is carried out to monitor agglutination. Since the visual inspection is no longer useful for obtaining precise quantitative information, therefore there is a wide variety of different technologies reported in the literature to recognize the agglutination reactions. Despite the classical methods, modern biosensors and molecular blood typing strategies have also been considered for straightforward, accurate and precise analysis. The interfacial part of a typical sensor device could range from natural antibodies to synthetic receptor materials, as designed by molecular imprinting and which is suitably integrated with the transducer surface. Herein, we present a comprehensive overview of some selected strategies extending from traditional practices to modern procedures in blood group typing, thus to highlight the most promising approach among emerging technologies.

Binding performance of pepsin surface-imprinted polymer particles in protein mixtures

Surface-imprinted polymer particles facilitate the accessibility of synthetic selective binding sites for proteins. Given their volume-to-surface ratio, submicron particles offer a potentially large surface area facilitating fast rebinding kinetics and high binding capacities, as investigated herein by batch rebinding experiments. Polymer particles were prepared with (3-acrylamidopropyl)trimethylammonium chloride as functional monomer, and ethylene glycol dimethacrylate as cross-linker in the presence of pepsin as template molecule via miniemulsion polymerization. The obtained polymer particles had an average particle diameter of 623 nm, and a specific surface area of 50 m² g^-1. The dissociation constant and maximum binding capacity were obtained by fitting the Langmuir equation to the corresponding binding isotherm. The dissociation constant was 7.94 μM, thereby indicating a high affinity; the binding capacity was 0.72 μmol m^-2. The binding process was remarkably fast, as equilibrium binding was observed after just 1 min of incubation. The previously determined selectivity of the molecularly imprinted polymer for pepsin was for the first time confirmed during competitive binding studies with pepsin, bovine serum albumin, and β-lactoglobulin. Since pepsin has an exceptionally high content in acidic amino acids enabling strong interactions with positively charged quaternary ammonium groups of the functional monomers, another competitive protein, i.e., α1-acid glycoprotein, was furthermore introduced. This protein has a similarly high content in acidic amino acids, and was used for demonstrating the implications of ionic interactions on the achieved selectivity.

Stimulus-responsive hydrogels: Theory, modern advances, and applications

Over the past century, hydrogels have emerged as effective materials for an immense variety of applications. The unique network structure of hydrogels enables very high levels of hydrophilicity and biocompatibility, while at the same time exhibiting the soft physical properties associated with living tissue, making them ideal biomaterials. Stimulus-responsive hydrogels have been especially impactful, allowing for unprecedented levels of control over material properties in response to external cues. This enhanced control has enabled groundbreaking advances in healthcare, allowing for more effective treatment of a vast array of diseases and improved approaches for tissue engineering and wound healing. In this extensive review, we identify and discuss the multitude of response modalities that have been developed, including temperature, pH, chemical, light, electro, and shear-sensitive hydrogels. We discuss the theoretical analysis of hydrogel properties and the mechanisms used to create these responses, highlighting both the pioneering and most recent work in all of these fields. Finally, we review the many current and proposed applications of these hydrogels in medicine and industry.

A functional monomer is not enough: principal component analysis of the influence of template complexation in pre-polymerization mixtures on imprinted polymer recognition and morphology

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

A novel sensitive electrochemical sensor based on in-situ polymerized molecularly imprinted membranes at graphene modified electrode for artemisinin determination

To develop a rapid and simple method for sensitive determination of artemisinin (ART) in complicated matrices, a novel electrochemical sensor was constructed by in-situ polymerization of ART-imprinted membranes (ART-MIMs) on the surface of graphene (G) modified glassy carbon electrode (GCE) using acrylamide (AM) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent after the experimental parameters for the preparation of ART-MIMs such as functional monomer, molar ratio of template, monomer and cross-linking agent together with extraction condition were optimized. Under the optimal conditions, the sensor named as ART-MIM/G/GCE exhibited a good selectivity, high sensitivity and considerably better resistance against some analogs of artemisinin such as dihydroartemisinin (DHA), artemether (ARM) and artesunate (ARTS). The calibration graph for the determination of artemisinin by the sensor was linear in the range of 1.0 × 10(-8)mol L(-1) to 4.0 × 10(-5)mol L(-1) with the detection limit of 2.0 × 10(-9)mol L(-1). Meanwhile, this sensor possessed of good regeneration, stability and practicability. It could retain more than 94% of its original response after used at least 80 times or stored in water at room temperature for 60 days. The obtained sensor was successfully applied to determine the contents of artemisinin in the extract of Artemisia annua L. with the relative standard deviation (RSD) of less than 3.5% (n=5).

Study on a biomimetic enzyme-linked immunosorbent assay method for rapid determination of trace acrylamide in French fries and cracker samples

BACKGROUND

Acrylamide has attracted worldwide concern due to its neurotoxicity, genotoxicity, reproductive-development toxicity. It is necessary to develop an accurate and reliable analytical method to prevent the harm on the human health.

RESULTS

In this study, a sensitive and fast analytical method of direct competitive biomimetic enzyme-linked immunosorbent assay (BELISA) was developed using a hydrophilic imprinted membrane as biomimetic antibody. This novel imprinted membrane was directly synthesised on the well surface of MaxiSorp polystyrene 96-well plates in an aqueous environment, and it exhibited high binding ability and specificity toward acrylamide. Under the optimal conditions, the established BELISA method had a good sensitivity (IC50, 8.0 ± 0.4 mg L(-1)) and a low limit of detection (IC15, 85.0 ± 4.2 µg L(-1)). The blank potato samples spiked with acrylamide at three levels of 100, 250 and 500 µg L(-1) were extracted and determinate by the proposed method, and good recoveries ranging from 90.0% to 110.5% were obtained. This presented method was applied to the quantitative detection of the acrylamide in French fries and cracker samples. Also, the results were correlated well with that obtained by the gas chromatography method.

CONCLUSION

With good properties of high sensitivity, simple pre-treatment and low cost, this BELISA could be a promising screening method in food sample analysis.