Molecularly Imprinted Polymers

A Screen-Printed Voltammetric Sensor Modified with Electropolymerized Molecularly Imprinted Polymer (eMIP) to Determine Gallic Acid in Non-Alcoholic and Alcoholic Beverages

This paper presents a low-cost disposable sensor for gallic acid (GA) detection in non-alcoholic and alcoholic beverages using a screen-printed cell (SPC) whose working electrode (in graphite) is modified with electrosynthesized molecularly imprinted polypyrrole (eMIP). Our preliminary characterization of the electrochemical process shows that gallic acid (GA) undergoes irreversible oxidation at potentials of about +0.3 V. The peak potential is not affected by the presence of the eMIP film and alcohol percentages (ethanol) up to 20%. The GA determination is based on a differential pulse voltammetry (DPV) analysis leveraging its oxidation peak. The calibration data and the figures of merit of the analytical method (LOD, LOQ, and linear range) are calculated. To validate the feasibility of the sensor's application for the dosing of GA in real matrices, some non-alcoholic and alcoholic beverages are analyzed. The results are then compared with those reported in the literature and with the total polyphenol content determined by the Folin-Ciocalteu method. In all cases, the concentrations of GA align with those previously found in the literature for the beverages examined. Notably, the values are consistently lower than the total polyphenol content, demonstrating the sensor's selectivity in discriminating the target molecule from other polyphenols present.

Synthetic Peptide Antibodies as TNF-α Inhibitors: Molecularly Imprinted Polymer Nanogels Neutralize the Inflammatory Activity of TNF-α in THP-1 Derived Macrophages

Tumor Necrosis Factor-α (TNF-α) is a cytokine that is normally produced by immune cells when fighting an infection. But, when too much TNF-α is produced as in autoimmune diseases, this leads to unwanted and persistent inflammation. Anti-TNF-α monoclonal antibodies have revolutionized the therapy of these disorders by blocking TNF-α and preventing its binding to TNF-α receptors, thus suppressing the inflammation. Herein, we propose an alternative in the form of molecularly imprinted polymer nanogels (MIP-NGs). MIP-NGs are synthetic antibodies obtained by nanomoulding the 3-dimensional shape and chemical functionalities of a desired target in a synthetic polymer. Using an in-house developed in silico rational approach, epitope peptides of TNF-α were generated and 'synthetic peptide antibodies' were prepared. The resultant MIP-NGs bind the template peptide and recombinant TNF-α with high affinity and selectivity, and can block the binding of TNF-α to its receptor. Consequently they were applied to neutralize pro-inflammatory TNF-α in the supernatant of human THP-1 macrophages, leading to a downregulation of the secretion of pro-inflammatory cytokines. Our results suggest that MIP-NGs, which are thermally and biochemically more stable and easier to manufacture than antibodies, and cost-effective, are very promising as next generation TNF-α inhibitors for the treatment of inflammatory diseases.

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.

Fabrication of a Lactate-Specific Molecularly Imprinted Polymer toward Disease Detection

The development of sensitive and selective robust sensor materials for targeted biomarker detection aims to contribute to self-health monitoring and management. Molecularly imprinted polymeric (MIP) materials can perform as biomimetic recognition elements via tailored routes of synthesis for specific target analyte extraction and/or detection. In this work, a sensitive- and selective-lactate MIP has been developed utilizing methacrylic acid and ethylene glycol dimethacrylate as the functional monomer and cross-linker, respectively. The sensitivity of the as-synthesized imprinted species was evaluated by determining the target analyte retention, imprinting factor, and selectivity adsorption of up to 63.5%, 6.86, and 0.82, respectively. MIP selectivity elucidated the imprinting mechanism between the functional monomers and target analyte lactate, further experimentally evidenced by using structurally competitive analytes malic acid and sodium 2-hydroxybutyrate, where retentions of 22.6 and 25.2%, respectively, were observed. Understanding the specific intermolecular mechanisms of both the template analyte and structural interferents with the MIP enables experimentalists to make informed decisions regarding monomer-target and porogen selections and possible sites of interaction for improved molecular imprinting. This imprinting system highlights the potential to be further developed into artificial receptor sensor materials for the detection of disease.

Molecularly Imprinted Polymers as Synthetic Antibodies for Protein Recognition: The Next Generation

Molecularly imprinted polymers (MIPs) are chemical antibody mimics obtained by nanomoulding the 3D shape and chemical functionalities of a desired target in a synthetic polymer. Consequently, they possess exquisite molecular recognition cavities for binding the target molecule, often with specificity and affinity similar to those of antigen-antibody interactions. Research on MIPs targeting proteins began in the mid-90s, and this review will evaluate the progress made till now, starting from their synthesis in a monolith bulk format through surface imprinting to biocompatible soluble nanogels prepared by solid-phase synthesis. MIPs in the latter format will be discussed more in detail because of their tremendous potential of replacing antibodies in the biomedical domain like in diagnostics and therapeutics, where the workforce of antibodies is concentrated. Emphasis is also put on the development of epitope imprinting, which consists of imprinting a short surface-exposed fragment of a protein, resulting in MIPs capable of selectively recognizing the whole macromolecule, amidst others in complex biological media, on cells or tissues. Thus selecting the 'best' peptide antigen is crucial and in this context a rational approach, inspired from that used to predict peptide immunogens for peptide antibodies, is described for its unambiguous identification.

Silk and its composites for humidity and gas sensing applications

Silk fibroin (SF) is a natural protein largely used in the textile industry with applications in bio-medicine, catalysis as well as in sensing materials. SF is a fiber material which is bio-compatible, biodegradable, and possesses high tensile strength. The incorporation of nanosized particles into SF allows the development of a variety of composites with tailored properties and functions. Silk and its composites are being explored for a wide range of sensing applications like strain, proximity, humidity, glucose, pH and hazardous/toxic gases. Most studies aim at improving the mechanical strength of SF by preparing hybrids with metal-based nanoparticles, polymers and 2D materials. Studies have been conducted by introducing semiconducting metal oxides into SF to tailor its properties like conductivity for use as a gas sensing material, where SF acts as a conductive path as well as a substrate for the incorporated nanoparticles. We have reviewed gas and humidity sensing properties of silk, silk with 0D (i.e., metal oxide), 2D (e.g., graphene, MXenes) composites. The nanostructured metal oxides are generally used in sensing applications, which use its semiconducting properties to show variation in the measured properties (e.g., resistivity, impedance) due to analyte gas adsorption on its surface. For example, vanadium oxides (i.e., V₂O₅) have been shown as candidates for sensing nitrogen containing gases and doped vanadium oxides for sensing CO gas. In this review article we provide latest and important results in the gas and humidity sensing of SF and its composites.

Picomolar or beyond Limit of Detection Using Molecularly Imprinted Polymer-Based Electrochemical Sensors: A Review

Over the last decades, molecularly imprinted polymers (MIPs) have emerged as selective synthetic receptors that have a selective binding site for specific analytes/target molecules. MIPs are synthetic analogues to the natural biological antigen-antibody system. Owing to the advantages they exhibit, such as high stability, simple synthetic procedure, and cost-effectiveness, MIPs have been widely used as receptors/sensors for the detection and monitoring of a variety of analytes. Moreover, integrating electrochemical sensors with MIPs offers a promising approach and demonstrates greater potential over traditional MIPs. In this review, we have compiled the methods and techniques for the production of MIP-based electrochemical sensors along with the applications of reported MIP sensors for a variety of analytes. A comprehensive in-depth analysis of recent trends reported on picomolar (pM/10^-12 M)) and beyond picomolar concentration LOD (≥pM) achieved using MIPs sensors is reported. Finally, we discuss the challenges faced and put forward future perspectives along with our conclusion.

Modification of Cotton Fabric with Molecularly Imprinted Polymer-Coated Carbon Dots as a Sensor for 17 α-methyltestosterone

Molecularly imprinted polymers@ethylenediamine-modified carbon dots grafted on cotton fabrics (MIPs@EDA-CDs/CF) and smartphone-based fluorescence image analysis were proposed and used for the first time for the detection of 17 α-methyltestosterone (MT). The EDA-CDs were synthesized and grafted on cotton fabric before coating with the MIPs. The MIPs were synthesized using the MT as a template molecule, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, and azobisisobutyronitrile (AIBN) as an initiator. The MIPs@EDA-CDs/CF were characterized using FTIR, SEM-EDS, and RGB fluorescence imaging. The fluorescence images were also taken using a smartphone and the ImageJ program was used for RGB measurement. The Δ red intensity was linearly proportional to MT concentration in the range of 100 to 1000 μg/L (R2 = 0.999) with a detection limit of 44.4 μg/L and quantification limit of 134 μg/L. The MIPs@EDA-CDs/CF could be stored at 4 °C for a few weeks and could be reused twice. The proposed method could apply for the specific determination of MT in water and sediment samples along with satisfactory recoveries of 96-104% and an acceptable relative standard deviation of 1-6% at the ppb level.

Electrospun Porous Nanofibers with Imprinted Patterns Induced by Phase Separation of Immiscible Polymer Blends

Nanofibrous nonwoven fabrics have attracted attention as porous adsorbents with high specific surface areas for the safe and efficient treatment of spilled organic dyes and petroleum. For this purpose, a method of fabricating porous nanofibers with high specific surface areas would be highly beneficial. In this study, the phase separation in nanofibers electrospun from blended solutions of immiscible polymers [poly(styrene) (PS) and poly(vinylpyrrolidone) (PVP)] was investigated. The removal of PVP as a sacrificial polymer afforded the imprinting of mesopores (40-70 nm) in the PS nanofibers. The effects of solution composition (PS/PVP in N,N-dimethylformamide) on the structure formation in the fibers were investigated. The nanofibers thus obtained could selectively adsorb low-molecular-weight hydrophobic dyes, such as Nile Red and Oil Red O. Thus, it is expected that the combined approach of electrospinning of immiscible polymer blends and phase separation-induced patterning can be applied to the fabrication of functional nanofibers for diverse applications.

Hydrazone bond-oriented molecularly imprinted nanocomposites for the selective separation of protein via the well-defined recognition sites

The development of hydrazone bond-oriented epitope imprinting strategy is reported to synthesize the polymeric binders for the selective recognition of a protein-β₂-microglobulin through either its N- or C-terminal epitope. The dynamic reversibility of hydrazone bond facilitated not only the oriented assembly of the template peptide hydrazides onto the substrate but also the efficient removal of them from the imprinted cavities. The well-defined surface imprinted layer was successfully constructed through the precise control over the polymerization of silicate esters. Binding performance of the C-terminal peptide imprinted nanocomposite was significantly improved after tuning the non-covalent interactions using the sequence-matching aromatic co-monomers. The dissociation constant (K_d) between the optimized nanocomposite and epitope peptide was 0.5 µmol L^-1. The nanomaterial was utilized for the selective extraction and determination of β₂-microglobulin from human urine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and HPLC-UV with satisfied recoveries of 93.1-112.3% in a concentration range 1.0-50.0 μg⋅mL^-1.

Application of the Remote Interaction Effect and Molecular Imprinting in Sorption of Target Ions of Rare Earth Metals

The goal of the present work is a comparative study of the effectiveness of the application of intergel systems and molecularly imprinted polymers for the selective sorption and separation of neodymium and scandium ions. The following physico-chemical methods of analysis were used in this study: colorimetry and atomic-emission spectroscopy. The functional polymers of polyacrylic acid (hPAA) and poly-4-vinylpyridine (hP4VP) in the intergel system undergo significant changes in the initial sorption properties. The remote interaction of the polymers in the intergel system hPAA–hP4VP provides mutual activation of these macromolecules, with subsequent transfer into a highly ionized state. The maximum sorption of neodymium and scandium ions is observed at molar ratios of 83%hPAA:17%hP4VP and 50%hPAA:50%hP4VP. Molecularly imprinted polymers MIP(Nd) and MIP(Sc) show good results in the sorption of Nd and Sc ions. Based on both these types of these macromolecular structures, principally new sorption methods have been developed. The method based on the application of the intergel system is cheaper and easier in application, but there is some accompanying sorption (about 10%) of another metal from the model solution during selective sorption and separation. Another method, based on the application of molecularly imprinted polymers, is more expensive and the sorption properties are higher, with the simultaneous sorption of the accompanying metal from the model solution.

QCM-based assay designs for human serum albumin

Solid-phase synthesis is an elegant way to create molecularly imprinted polymer nanoparticles (nano-MIPs) comprising a single binding site, i.e. mimics of antibodies. When using human serum albumin (HSA) as the template, one achieves nano-MIPs with 53 ± 19 nm diameter, while non-imprinted polymer nanoparticles (nano-NIPs) reach 191 ± 96 nm. Fluorescence assays lead to Stern-Volmer plots revealing selective binding to HSA with selectivity factors of 1.2 compared to bovine serum albumin (BSA), 1.9 for lysozyme, and 4.1 for pepsin. Direct quartz crystal microbalance (QCM) assays confirm these results: nano-MIPs bind to HSA immobilized on QCM surfaces. This opens the way for competitive QCM-based assays for HSA: adding HSA to nanoparticle solutions indeed reduces binding to the QCM surfaces in a concentration-dependent manner. They achieve a limit of detection (LoD) of 80 nM and a limit of quantification (LoQ) of 244 nM. Furthermore, the assay shows recovery rates around 100% for HSA even in the presence of competing analytes.

Development of a MIP-Based QCM Sensor for Selective Detection of Penicillins in Aqueous Media

Pharmaceuticals wastes have been recognized as emerging pollutants to the environment. Among those, antibiotics in the aquatic environment are one of the major sources of concern, as chronic, low-dose exposure can lead to antibiotic resistance. Herein, we report on molecularly imprinted polymers (MIP) to recognize penicillin V potassium salt (PenV-K), penicillin G potassium salt (PenG-K), and amoxicillin sodium salt (Amo-Na), which belong to the most widespread group of antibiotics worldwide. Characterization and optimization led to two MIPs comprising methacrylic acid as the monomer and roughly 55% ethylene glycol dimethacrylate as the crosslinker. The obtained layers led to sensitive, selective, repeatable, and reusable sensor responses on quartz crystal microbalances (QCM). The LoD for PenV-K, PenG-K, and Amo-Na sensors are 0.25 mM, 0.30 mM, and 0.28 mM, respectively; imprinting factors reach at least around three. Furthermore, the sensors displayed relative selectivity factors of up to 50% among the three penicillins, which is appreciable given their structural similarity.

Molecularly Imprinted Polymer Hydrogel Nanoparticles: Synthetic Antibodies for Cancer Diagnosis and Therapy

Cancer is a leading cause of death worldwide and according to the World Health Organization (WHO) accounted for 10 million deaths in 2020. Promising theranostic (therapy and diagnostic) agents in the treatment of cancer are nanomaterials, which have come to the forefront because of their small size approaching those of protein complexes in the human body, and of their easy functionalization giving access to nanocomposite materials with diverse functions (fluorescence, magnetic, stimuli-responsiveness, etc.), and improved biocompatibility. Among them, affinity nanoparticles, often decorated with highly specific targeting ligands such as antibodies, aptamers, lectins and peptides, have enabled enhanced binding and exquisite recognition of biomarkers overexpressed in cancer cells. In this review, we describe an emerging class of targeting ligands, molecularly imprinted polymer hydrogel nanoparticles for their application in the early detection of disease, with the aim to improve diagnosis and treatment.

Fighting Antibiotic-Resistant Bacteria : Promising Strategies Orchestrated by Molecularly Imprinted Polymers

Infections caused by antibiotic-resistant bacteria are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. We highlight how one unique material , molecularly imprinted polymers (MIPs), can orchestrate several strategies to fight this major societal issue. MIPs are tailor-made biomimetic supramolecular receptors that recognize and bind target molecules with a high affinity and selectivity, comparable to those of antibodies. While research on MIPs for combatting cancer has been constantly flourishing, comprehensive work on their involvement in combatting resistant superbugs has been rather scarce. This review aims at filling this gap. We will describe what are the causes of bacterial resistance and at which level MIPs can deploy their weapons. MIPs' targets can be biofilm constituents, quorum sensing messengers, bacterial surface proteins and antibiotic-deactivating enzymes, among others. We will conclude on the current challenges and future developments in this field.

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

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

Comparison and recent progress of molecular imprinting technology and dummy template molecular imprinting technology

Molecular imprinting technology for the preparation of polymers with specific molecular recognition function had become one of the current research hotspots. It has been widely applied in chromatographic separation, antibody and receptor mimetics, solid-phase extraction, bio-sensors, and other fields in the last decades. In this study, molecular imprinting technology was summarized from the points of templates and dummy templates, and four typical target analytes were selected to compare the differences between templates and dummy templates. The current status and prospects of molecular imprinting technology were also proposed.

Molecularly Imprinted Polymer Nanogels for Protein Recognition: Direct Proof of Specific Binding Sites by Solution STD and WaterLOGSY NMR Spectroscopies

Molecularly imprinted polymers (MIPs) are tailor-made synthetic antibodies possessing specific binding cavities designed for a target molecule. Currently, MIPs for protein targets are synthesized by imprinting a short surface-exposed fragment of the protein, called epitope or antigenic determinant. However, finding the epitope par excellence that will yield a peptide "synthetic antibody" cross-reacting exclusively with the protein from which it is derived, is not easy. We propose a computer-based rational approach to unambiguously identify the "best" epitope candidate. Then, using Saturation Transfer Difference (STD) and WaterLOGSY NMR spectroscopies, we prove the existence of specific binding sites created by the imprinting of this peptide epitope in the MIP nanogel. The optimized MIP nanogel could bind the epitope and cognate protein with a high affinity and selectivity. The study was performed on Hepatitis A Virus Cell Receptor-1 protein, also known as KIM-1 and TIM-1, for its ubiquitous implication in numerous pathologies.

Molecular Imprinting: Green Perspectives and Strategies

Advances in revolutionary technologies pose new challenges for human life; in response to them, global responsibility is pushing modern technologies toward greener pathways. Molecular imprinting technology (MIT) is a multidisciplinary mimic technology simulating the specific binding principle of enzymes to substrates or antigens to antibodies; along with its rapid progress and wide applications, MIT faces the challenge of complying with green sustainable development requirements. With the identification of environmental risks associated with unsustainable MIT, a new aspect of MIT, termed green MIT, has emerged and developed. However, so far, no clear definition has been provided to appraise green MIT. Herein, the implementation process of green chemistry in MIT is demonstrated and a mnemonic device in the form of an acronym, GREENIFICATION, is proposed to present the green MIT principles. The entire greenificated imprinting process is surveyed, including element choice, polymerization implementation, energy input, imprinting strategies, waste treatment, and recovery, as well as the impacts of these processes on operator health and the environment. Moreover, assistance of upgraded instrumentation in deploying greener goals is considered. Finally, future perspectives are presented to provide a more complete picture of the greenificated MIT road map and to pave the way for further development.

Magnetic-molecularly imprinted polymers in electrochemical sensors and biosensors

Magnetic particles, as well as molecularly imprinted polymers, have revolutionized separation and bioanalytical methodologies in the 1980s due to their wide range of applications. Today, biologically modified magnetic particles are used in many scientific and technological applications and are integrated in more than 50,000 diagnostic instruments for the detection of a huge range of analytes. However, the main drawback of this material is their stability and high cost. In this work, we review recent advances in the synthesis and characterization of hybrid molecularly imprinted polymers with magnetic properties, as a cheaper and robust alternative for the well-known biologically modified magnetic particles. The main advantages of these materials are, besides the magnetic properties, the possibility to be stored at room temperature without any loss in the activity. Among all the applications, this work reviews the direct detection of electroactive analytes based on the preconcentration by using magnetic-MIP integrated on magneto-actuated electrodes, including food safety, environmental monitoring, and clinical and pharmaceutical analysis. The main features of these electrochemical sensors, including their analytical performance, are summarized. This simple and rapid method will open the way to incorporate this material in different magneto-actuated devices with no need for extensive sample pretreatment and sophisticated instruments.

Synthesis of monodisperse magnetic restricted microspheres for recognition of thiamphenicol in milk

Taking thiamphenicol as the research object, a new type of magnetic restricted access molecularly imprinted polymer (RAM-MMIP) with specific recognition was prepared by a one-step swelling method.

Molecularly Imprinted Synthetic Antibodies: From Chemical Design to Biomedical Applications

Billions of dollars are invested into the monoclonal antibody market every year to meet the increasing demand in clinical diagnosis and therapy. However, natural antibodies still suffer from poor stability and high cost, as well as ethical issues in animal experiments. Thus, developing antibody substitutes or mimics is a long-term goal for scientists. The molecular imprinting technique presents one of the most promising strategies for antibody mimicking. The molecularly imprinted polymers (MIPs) are also called "molecularly imprinted synthetic antibodies" (MISAs). The breakthroughs of key technologies and innovations in chemistry and material science in the last decades have led to the rapid development of MISAs, and their molecular affinity has become comparable to that of natural antibodies. Currently, MISAs are undergoing a revolutionary transformation of their applications, from initial adsorption and separation to the rising fields of biomedicine. Herein, the fundamental chemical design of MISAs is examined, and then current progress in biomedical applications is the focus. Meanwhile, the potential of MISAs as qualified substitutes or even to transcend the performance of natural antibodies is discussed from the perspective of frontier needs in biomedicines, to facilitate the rapid development of synthetic artificial antibodies.

Delayed Addition of Template Molecules Enhances the Binding Properties of Diclofenac-Imprinted Polymers

It has been reported that in the molecular imprinting technique, the use of preformed oligomers instead of functional monomers increases the stability of the non-covalent interactions with the template molecule, providing a sharp gain in terms of binding properties for the resulting imprinted polymer. Based on this theory, we assumed that the delayed addition of template molecules to a polymerization mixture enhances the binding properties of the resulting polymer. To verify this hypothesis, we imprinted several mixtures of 4-vinylpyridine/ethylene dimethacrylate (1:6 mol/mol) in acetonitrile by adding diclofenac progressively later from the beginning of the polymerization process. After polymerization, the binding isotherms of imprinted and non-imprinted materials were measured in acetonitrile by partition equilibrium experiments. Binding data confirm our hypothesis, as imprinted polymers prepared by delayed addition, with delay times of 5 and 10 min, showed higher binding affinity (K_eq = 1.37 × 10⁴ L mol⁻¹ and 1.80 × 10⁴ L mol⁻¹) than the polymer obtained in the presence of template at the beginning (K_eq = 5.30 × 10³ L mol⁻¹). Similarly, an increase in the imprinting factor measured vs. the non-imprinted polymer in the binding selectivity with respect to mefenamic acid was observed. We believe that the delayed addition approach could be useful in prepar imprinted polymers with higher binding affinity and increased binding selectivity in cases of difficult imprinting polymerization.

Assessment of Dimethoate in Olive Oil Samples Using a Dual Responsive Molecularly Imprinting-Based Approach

A new generation of advanced materials developed by molecular imprinting technology showing a stimuli-responsive functionality are emerging. The switchable ability to control the uptake/release of the target analyte by action of external stimulus combined with a remarkable selectivity and specificity, makes these functional materials very attractive for sample preparation purposes. In this work, the usefulness of a sample preparation tool for the selective enrichment/pre-concentration of dimethoate from olive oil spiked samples based on "tailor-made" dual responsive magnetic and photonic molecularly imprinted polymers as sorbents is explored. To achieve this goal, a smart molecularly imprinted polymer (MIP) possessing magnetic and photonic responsiveness was successfully synthesized, and its physico-chemical and morphological characterization was assessed. Further, the trace analysis of dimethoate in spiked olive oil samples was validated and successfully implemented using smart-MIPs as sorbents in the sample preparation step, with high recoveries (83.5 ± 0.3%) and low detection limit (0.03µg·mL-1).

How Reliable Is the Electrochemical Readout of MIP Sensors?

Electrochemical methods offer the simple characterization of the synthesis of molecularly imprinted polymers (MIPs) and the readouts of target binding. The binding of electroinactive analytes can be detected indirectly by their modulating effect on the diffusional permeability of a redox marker through thin MIP films. However, this process generates an overall signal, which may include nonspecific interactions with the nonimprinted surface and adsorption at the electrode surface in addition to (specific) binding to the cavities. Redox-active low-molecular-weight targets and metalloproteins enable a more specific direct quantification of their binding to MIPs by measuring the faradaic current. The in situ characterization of enzymes, MIP-based mimics of redox enzymes or enzyme-labeled targets, is based on the indication of an electroactive product. This approach allows the determination of both the activity of the bio(mimetic) catalyst and of the substrate concentration.

Synthesis of molecularly imprinted polymer for removal of Congo red

Congo red (CR) is an anionic azo dye widely used in many industries including pharmaceutical, textile, food and paint industries. The disposal of huge amount of CR into the various streams of water has posed a great threat to both human and aquatic life. Therefore, it has become an important aspect of industries to remove CR from different water sources. Molecular imprinting technology is a very slective method to remove various target pollutant from environment. In this study a precipitation polymerization was employed for the effective and selective removal of CR from contaminated aqueous media. A series of congo red molecularly imprinted polymers (CR-MIPs) of uniform size and shape was developed by changing the mole ratio of the components. The optimum ratio (0.1:4: 20, template, functional monomer and cross-linking monomer respectively) for CR1-MIP from synthesized polymers was able to rebind about 99.63% of CR at the optimum conditions of adsorption parameters (contact time 210 min, polymer dosage 0.5 g, concentration 20 ppm and pH 7). The synthesized polymers were characterized by various techniques such as Fourier Infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), and Brumauer-Emmett-Teller (BET). The polymer particles have successfully removed CR from different aqueous media with an efficiency of about ~ 90%.

Insights on the Molecular Characteristics of Molecularly Imprinted Polymers as Monitored by Sum Frequency Generation Spectroscopy

Sensing in molecularly imprinted polymers (MIPs) requires specific interactions of the imprinted polymer and the approaching template molecule. These interactions are affected by the morphology of the polymer surface, the affinity of the template molecule to the polymer network, and the steric approach. In this particular study, a template molecule, metronidazole, is studied with respect to the typically used methacrylic acid-based imprinted polymer using a combination of bulk and surface techniques. The resulting infrared (IR) spectra exhibited the presence of the template molecule in the polymer matrix as well as their efficient removal after washing. Dipping of the MIP according to what is expected of facile sensing in an aqueous solution of metronidazole did not show any presence of the template molecule in the bulk of the MIP, as observed by IR spectroscopy. However, using sum frequency generation (SFG) spectroscopy, the CH aromatic stretch of the imidazole ring positioned at ∼3100 cm^-1 was observed at the polymer surface, including its inner pores or cavities, and at the buried polymer-fused silica interface after dipping. SFG studies have also shown the vibrational signatures of the polymer matrix, the presence of the template molecule on the surface, and the detection of residual template molecules after washing. Increasing the washing time to 50 min has proven to be less effective than increasing the washing cycles to three. However, after the third cycle, reorganization of the polymer matrix was evident as also the complete removal of the template molecule. The observed changes from the acquired images using scanning electron microscopy and atomic force microscopy show the structural morphologies of MIPs and a good distribution of the pores across the MIP surface. The study demonstrates the importance of combining both bulk and surface characterization in providing insight into the template molecule-polymer network interactions.

A Nanostructured Microfluidic Artificial Olfaction for Organic Vapors Recognition

Selective and sensitive detection of volatile organic compounds (VOCs) is of great importance in applications involving monitoring of hazardous chemicals or non-invasive diagnosis. Here, polymethyl methacrylate nanoparticles with acetone recognition sites are synthesized and integrated into a 3D-printed microfluidic platform to enhance the selectivity of the device. The proposed microfluidic-based olfaction system includes two parylene C-coated microchannels, with or without polymer nanoparticles. The two channels are exposed to 200, 400, 800, 2000, and 4000 ppm of VOCs (methanol, ethanol, acetone, acetonitrile, butanone, and toluene), and sensor responses are compared using a 2D feature extraction method. Compared to current microfluidic-based olfaction systems, responses observed between coated and uncoated channels showed an increased recognition capability among VOCs (especially with respect to acetone), indicating the potential of this approach to increase and fine-tune the selectivity of microfluidic gas sensors.

Peptides, Antibodies, Peptide Antibodies and More

The applications of peptides and antibodies to multiple targets have emerged as powerful tools in research, diagnostics, vaccine development, and therapeutics. Antibodies are unique since they, in theory, can be directed to any desired target, which illustrates their versatile nature and broad spectrum of use as illustrated by numerous applications of peptide antibodies. In recent years, due to the inherent limitations such as size and physical properties of antibodies, it has been attempted to generate new molecular compounds with equally high specificity and affinity, albeit with relatively low success. Based on this, peptides, antibodies, and peptide antibodies have established their importance and remain crucial reagents in molecular biology.

Conjugated Oligo- and Polymers for Bacterial Sensing

Fast and accurate detection of bacteria and differentiation between pathogenic and commensal colonization are important keys in preventing the emergence and spread of bacterial resistance toward antibiotics. As bacteria undergo major lifestyle changes during colonization, bacterial sensing needs to be achieved on different levels. In this review, we describe how conjugated oligo- and polymers are used to detect bacterial colonization. We summarize how oligothiophene derivatives have been tailor-made for detection of biopolymers produced by a wide range of bacteria upon entering the biofilm lifestyle. We further describe how these findings are translated into diagnostic approaches for biofilm-related infections. Collectively, this provides an overview on how synthetic biorecognition elements can be used to produce fast and easy diagnostic tools and new methods for infection control.

Design of Synthetic Polymer Nanoparticles Specifically Capturing Indole, a Small Toxic Molecule

Synthetic polymers are of interest as stable and cost-effective biomolecule-affinity reagents, since these polymers interact with target biomolecules both in vitro and in the bloodstream. However, little has been reported about orally administered polymers capable of capturing a target molecule and inhibiting its intestinal absorption. Here, we describe the design of synthetic polymer nanoparticles (NPs) specifically capturing indole, a major factor exacerbating chronic kidney disease, in the intestine. N-isopropylacrylamide-based NPs were prepared with various hydrophobic monomers. The amounts of indole captured by NPs depended on the structures and feed ratios of the hydrophobic monomers and the polymer density but not on the particle size. The combination of hydrophobic and quadrupole interaction was effective to enhance the affinity and specificity of NPs for indole. The optimized NPs specifically inhibited intestinal absorption of orally administered indole in mice. These results showed the potential of synthetic polymer NPs for inhibiting the intestinal absorption of a target molecule.

Molecularly Imprinted Polymer Nanoparticles as Potential Synthetic Antibodies for Immunoprotection against HIV

We describe the preparation and characterization of synthetic antibodies based on molecularly imprinted polymer nanoparticles (MIP-NPs) for the recognition and binding of the highly conserved and specific peptide motif SWSNKS (3S), an epitope of the envelope glycoprotein 41 (gp41) of human immunodeficiency virus type 1 (HIV-1). This motif is implicated in the decline of CD4⁺ T cells and leads to the deterioration of the immune system during HIV infection. Therefore, the development of MIP-NPs that can target and block the 3S peptide to prevent subsequent cascade interactions directed toward the killing of CD4⁺ T cells is of prime importance. Because most antibodies recognize their protein antigen via a conformational or structured epitope (as opposed to a linear epitope commonly used for molecular imprinting), we employed protein molecular modeling to design our template epitope so that it mimics the three-dimensional structure fold of 3S in gp41. The resulting template peptide corresponds to a cyclic structure composed of CGSWSNKSC, with the 3S motif well orientated for imprinting. MIP-NPs with a size of 65 nm were obtained by solid-phase synthesis and were water-soluble. They were prepared by a judicious combination of multiple functional monomers affording hydrogen bonding, ionic, π-π, and hydrophobic interactions, conferring high affinity and selectivity toward both the cyclic peptide and the whole gp41 protein. These results suggest that our MIPs could potentially be used for blocking the function of the 3S motif on the virus.

Solid-phase synthesis of molecularly imprinted polymer nanolabels: Affinity tools for cellular bioimaging of glycans

Hyaluronic acid (HA) is a glycosaminoglycan that plays many roles in health and disease and is a key biomarker of certain cancers. Therefore, its detection at an early stage, by histochemical methods, is of importance. However, intracellular HA can be masked by other HA-binding macromolecules, rendering its visualization somehow problematic. We show that fluorescent molecularly imprinted polymer nanogels (MIP-NPs), can localize and detect intracellular HA. MIP-NPs were synthesized by solid-phase synthesis on glass beads (GBs). GBs were functionalized with terminal alkyne groups on which an azide derivative of the template molecule glucuronic acid was immobilized via click chemistry. Immobilization via the anomeric carbon left the template's carboxyl moiety free to enable strong stoichiometric electrostatic interactions with a benzamidine-based functional monomer, to confer selective recognition to the MIP-NPs. Due to the two-point orientation of the template, the resulting MIP-NPs were endowed with improved binding site homogeneity and specificity, reminiscent of monoclonal antibodies. These synthetic antibodies were then applied for probing and staining HA, of which glucuronic acid is a substructure (epitope), on human epidermal cells. Their excellent sensitivity, small size and water compatibility, enabled the MIP-NPs to visualize HA, as evidenced by confocal fluorescence micrographs.

Chemical and Sensory Evaluation of Magnetic Polymers as a Remedial Treatment for Elevated Concentrations of 3-Isobutyl-2-methoxypyrazine in Cabernet Sauvignon Grape Must and Wine

3-Isobutyl-2-methoxypyrazine (IBMP) is a potent odorant present in grapes and wines that is reminiscent of green capsicum. Suprathreshold concentrations can lead to obvious vegetative characters and suppress desirable fruity aroma nuances in wines, but options to manage IBMP concentrations are limited. This work investigated pre- and postfermentation addition of a putative imprinted magnetic polymer (PIMP) as a remedial treatment for elevated concentrations of IBMP in Cabernet Sauvignon grape must in comparison to nonimprinted magnetic polymer (NIMP) and to a commercially available polylactic acid (PLA) based film added postfermentation. Chemical and sensory analyses of wines showed that PIMP treatments were more effective than PLA film for decreasing "fresh green" aroma nuances without negatively impacting overall aroma profiles and that postfermentation addition of a magnetic polymer removed up to 74% of the initial IBMP concentration compared to 18% for PLA. Prefermentation addition of magnetic polymers removed 20-30% less IBMP compared to that of postfermentation addition but also had less of an effect on other wine volatiles and color parameters.

Preparation of Magnetic Polymers for the Elimination of 3-Isobutyl-2-Methoxypyrazine from Wine

3-Isobutyl-2-methoxypyrazine (IBMP), the most prevalent grape-derived methoxypyrazine, can contribute green bell pepper, vegetative and herbaceous aromas and flavours to wines. At elevated concentrations, this potent odorant may mask desirable fruity and floral aromas in wine and may be considered as a fault. A new remediation method for wines with elevated IBMP levels has been trialled using magnetic polymers, prepared in the same way as ordinary polymers but with the incorporation of iron oxide nanoparticles as magnetic substrates. Characterisation by Fourier transform-infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) showed no difference between thermally synthesised and microwave synthesised polymers. Magnetic polymers were found to have removed over 40% of the IBMP present in spiked model wine and white wine within ten minutes. The addition of magnetic nanoparticles and microwave-induced polymerisation did not affect the adsorption properties of the polymer in model wine and the polymer could be regenerated at least five times. Both Langmuir and Freundlich isotherms were found to fit the data for both types of polymer. However, attempts to produce imprinted polymers were not achieved, as they were found not to be differentiated from non-imprinted counterparts via adsorption tests.

Molecularly Imprinted Polymers as Extracting Media for the Chromatographic Determination of Antibiotics in Milk

Milk-producing animals are typically kept stationary in overcrowded large-scale farms and in most cases under unsanitary conditions, which promotes the development of infections. In order to maintain sufficient health status among the herd or promote growth and increase production, farmers administer preventative antibiotic doses to the animals through their feed. However, many antibiotics used in cattle farms are intended for the treatment of bacterial infections in humans. This results in the development of antibiotic-resistant bacteria which pose a great risk for public health. Additionally, antibiotic residues are found in milk and dairy products, with potential toxic effects for the consumers. Hence the need of antibiotic residues monitoring in milk arises. Analytical methods were developed for the determination of antibiotics in milk, with key priority given to the analyte extraction and preconcentration step. Extraction can benefit from the production of molecularly imprinted polymers (MIPs) that can be applied as sorbents for the extraction of specific antibiotics. This review focuses on the principals of molecular imprinting technology and synthesis methods of MIPs, as well as the application of MIPs and MIPs composites for the chromatographic determination of various antibiotic categories in milk found in the recent literature.

Tracking Hyaluronan: Molecularly Imprinted Polymer Coated Carbon Dots for Cancer Cell Targeting and Imaging

War against cancer constantly requires new affinity tools to selectively detect, localize, and quantify biomarkers for diagnosis or prognosis. Herein, carbon nanodots (CDs), an emerging class of fluorescent nanomaterials, coupled with molecularly imprinted polymers (MIPs), are employed as a biocompatible optical imaging tool for probing cancer biomarkers. First, N-doped CDs were prepared by hydrothermal synthesis using starch as carbon source and l-tryptophan as nitrogen atom provider to achieve a high quantum yield of 25.1 ± 2%. The CDs have a typical size of ∼3.2 nm and produce an intense fluorescence at 450 nm upon excitation with UV light. A MIP shell for specific recognition of glucuronic acid (GlcA) was then synthesized around the CDs, using the emission of the CDs as an internal light source for photopolymerization. GlcA is a substructure (epitope) of hyaluronan, a biomarker for certain cancers. The biotargeting and bioimaging of hyaluronan on fixated human cervical cancer cells using CD core-MIP shell nanocomposites is demonstrated. Human keratinocytes were used as noncancerous reference cells and indeed, less staining was observed by the CD-MIP.

A high selective methanol gas sensor based on molecular imprinted Ag-LaFeO3 fibers

Ag-LaFeO₃ molecularly imprinted polymers (ALMIPs) were fabricated, which provided special recognition sites to methanol. Then ALMIPs fiber 1, fiber 2 and fiber 3 were prepared using filter paper, silk and carbon fibers template, respectively. Based on the observation of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Nitrogen adsorption surface area analyzer (BET), the structure, morphology and surface area of the fibers were characterized. The ALMIPs fibers (fiber 1, fiber 2 and fiber 3) show excellent selectivity and good response to methanol. The responses to 5 ppm methanol and the optimal operating temperature of ALMIPs fibers are 23.5 and 175 °C (fiber 1), 19.67 and 125 °C (fiber 2), 17.59 and 125 °C (fiber 3), and a lower response (≤10, 3, 2) to other test gases including formaldehyde, acetone, ethanol, ammonia, gasoline and benzene was measured, respectively.

Core-Shell Molecularly Imprinted Polymer Nanoparticles as Synthetic Antibodies in a Sandwich Fluoroimmunoassay for Trypsin Determination in Human Serum

We describe the application of a fluorescently labeled water-soluble core-shell molecularly imprinted polymer (MIP) for fluorescence immunoassay (FIA) to detect trypsin. p-Aminobenzamidine (PAB), a competitive inhibitor of trypsin, was immobilized in the wells of a microtiter plate enabling the capture of trypsin in an oriented position, thus maintaining its native conformation. Fluorescent MIP nanoparticles, which bound selectively to trypsin, were used for quantification. The MIP was prepared by a multistep solid-phase synthesis approach on glass beads functionalized with PAB, orientating all trypsin molecules in the same way. The core-MIP was first synthesized, using a thermoresponsive polymer based on N-isopropylacrylamide, so as to enable its facile liberation from the immobilized template by a simple temperature change. The shell, mainly composed of allylamine to introduce primary amino groups for postconjugation of fluorescein isothiocyanate (FITC), was grafted in situ on the core-MIP, whose binding cavities were still bound and protected by the immobilized trypsin. The resulting core-shell MIP was endowed with a homogeneous population of high-affinity binding sites, all having the same orientation. The MIP has no or little cross-reactivity with other serine proteases and unrelated proteins. Our MIP-based FIA system was successfully applied to detect low trypsin concentrations spiked into nondiluted human serum with a low limit of quantification of 50 pM, which indicates the significant potential of this assay for analytical and biomedical diagnosis applications.