Recent developments in the molecular imprinting of proteins

Magnetic Nanoparticles with Surface Nanopockets for Highly Selective Antibody Isolation

Monoclonal antibodies (mAbs) are key components of revolutionary disease immunotherapies and are also essential for medical diagnostics and imaging. The impact of cost is illustrated by a price >$200,000 per year per patient for mAb-based cancer therapy. Purification represents a major issue in the final cost of these immunotherapy drugs. Protein A (PrA) resins are widely used to purify antibodies, but resin cost, separation efficiency, reuse, and stability are major issues. This paper explores a synthesis strategy for low-cost, reusable, stable PrA-like nanopockets on core-shell silica-coated magnetic nanoparticles (NPs) for IgG antibody isolation. Mouse IgG_2a, a strong PrA binder, was used as a template protein, first attaching it stem-down onto the NP surface. The stem-down orientation of IgG_2a on the NP surface before polymerization is critical for designing the films to bind IgGs. Following this, 1-tetraethoxysilane and four organosilane monomers with functional groups capable of mimicking binding interactions of proteins with IgG antibody stems were reacted to form a thin polymer coating on the NPs. After blocking nonspecific binding sites, removal of the mouse IgG_2a provided nanopockets on the core-shell NPs that showed binding characteristics for antibodies remarkably similar to PrA. Both smooth and rough core-shell NPs were used, with the latter providing much larger binding capacities for IgGs, with an excellent selectivity slightly better than that of commercial PrA magnetic beads. This paper is the first report of IgG-binding NPs that mimic PrA selectivity. These nanopocket NPs can be used for at least 15 regeneration cycles, and cost/use was 57-fold less than a high-quality commercial PrA resin.

Evaluation of acrylamide-based molecularly imprinted polymer thin-sheets for specific protein capture-a myoglobin model

We evaluate a series of thin-sheet hydrogel molecularly imprinted polymers (MIPs), using a family of acrylamide-based monomers, selective for the target protein myoglobin (Mb). The simple production of the thin-sheet MIP offers an alternative biorecognition surface that is robust, stable and uniform, and has the potential to be adapted for biosensor applications. The MIP containing the functional monomer N-hydroxymethylacrylamide (NHMAm), produced optimal specific rebinding of the target protein (Mb) with 84.9% (± 0.7) rebinding and imprinting and selectivity factors of 1.41 and 1.55, respectively. The least optimal performing MIP contained the functional monomer N,N-dimethylacrylamide (DMAm) with 67.5% (± 0.7) rebinding and imprinting and selectivity factors of 1.11 and 1.32, respectively. Hydrogen bonding effects, within a protein-MIP complex, were investigated using computational methods and Fourier transform infrared (FTIR) spectroscopy. The quantum mechanical calculations predictions of a red shift of the monomer carbonyl peak is borne-out within FTIR spectra, with three of the MIPs, acrylamide, N-(hydroxymethyl) acrylamide, and N-(hydroxyethyl) acrylamide, showing peak downshifts of 4, 11, and 8 cm⁻¹, respectively.

Sol-gel process: the inorganic approach in protein imprinting

Proteins play a central role in the signal transmission in living systems since they are able to recognize specific biomolecules acting as cellular receptors, antibodies or enzymes, being themselves recognized by other proteins in protein/protein interactions, or displaying epitopes suitable for antibody binding. In this context, the specific recognition of a given protein unlocks a range of interesting applications in diagnosis and in targeted therapies. Obviously, this role is already fulfilled by antibodies with unquestionable success. However, the design of synthetic artificial systems able to endorse this role is still challenging with a special interest to overcome limitations of antibodies, in particular their production and their stability. Molecular Imprinted Polymers (MIPs) are attractive recognition systems which could be an alternative for the specific capture of proteins in complex biological fluids. MIPs can be considered as biomimetic receptors or antibody mimics displaying artificial paratopes. However, MIPs of proteins remains a challenge due to their large size and conformational flexibility, their complex chemical nature with multiple recognition sites and their low solubility in most organic solvents. Classical MIP synthesis conditions result in large polymeric cavities and unspecific binding sites on the surface. In this review, the potential of the sol-gel process as inorganic polymerization strategy to overcome the drawbacks of protein imprinting is highlighted. Thanks to the mild and biocompatible experimental conditions required and the use of water as a solvent, the inorganic polymerization approach better suited to proteins than organic polymerization. Through numerous examples and applications of MIPs, we proposed a critical evaluation of the parameters that must be carefully controlled to achieve sol-gel protein imprinting (SGPI), including the choice of the monomers taking part in the polymerization.

Facile construction of a molecularly imprinted polymer-based electrochemical sensor for the detection of milk amyloid A

A molecularly imprinted electrochemical sensor for the detection of serum amyloid A (MAA) in milk was established for early diagnosis of subclinical mastitis in dairy cows. The electrochemical sensor was initially constructed using a nanocomposite material (reduced graphene oxide/gold nanoparticles, AuNPs@rGO) to modify the working electrode. The template protein, MAA, was then immobilized using pyrrole as the functional monomer to carry out the electropolymerization. Finally, the template protein was removed to form a molecular imprint film with the capability to qualitatively and quantitatively signaling of MAA. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and scanning electron microscopy (SEM) were used to characterize the modification process of the molecularly imprinted electrochemical sensors. Under optimized conditions, the sensor shows two well-behaved linear relationships in the MAA concentration range 0.01 to 200 ng/mL. A lower detection limit was estimated to be 5 pg/mL (S/N = 3). Other parameters including the selectivity, reproducibility (RSD 3.2%), and recovery rate (96.1-103%) are all satisfactory. Compared with the traditional methods, detection of MAA to determine the subclinical mastitis of dairy cows can efficiently be diagnosed and hence prevent an outbreak of dairy cow mastitis. The electrochemical sensor can detect MAA more rapidly, sensitively, and inexpensively than the ELISA-based MAA detection. These advantages indicate that the method is promising for early diagnosis of dairy cows.

A fabrication strategy for protein sensors based on an electroactive molecularly imprinted polymer: Cases of bovine serum albumin and trypsin sensing

A high-performance molecularly imprinted sensing platform inspired by natural recognition mechanisms was fabricated to detect protein by employing a linear electro-polymerizable molecularly imprinted polymer as macromonomer. This was achieved via the combination of a biosensor fabrication with a self-assembly imprinting technique without the use of chemical labels. An amphipathic electroactive copolymer was designed as macro-monomer to maintain structural integrity of the protein template via self-assembly, resulting in generation of a 3D construction around the protein molecule to form imprinted sites. Electro-polymerization was utilized not only to anchor imprinted sites but also to enhance electron transfer. The adaptable sensing platform was based on a strengthened recognition reaction between the MIP layer and template protein after the generation of an electroactive network. Bovine serum albumin (BSA) and trypsin were used as model proteins to investigate the method's generality, which gave broad detection ranges of 10^-14-10^-5 mg mL^-1 for BSA and 10^-13-10^-8 mg mL^-1 for trypsin. These results indicate that the proposed fabrication offers an effective and versatile strategy for protein recognition.

Chromatographic separation of hemoglobin variants using robust molecularly imprinted polymers

Devising a robust, efficient and cost effective hemoglobin (Hb) purification strategy is one of the key challenges in the development of Hb-based blood substitutes. The aim of this study was to use molecularly imprinted polymers (MIPs) as a novel and efficient chromatographic resin to selectively recognize and purify different Hb variants. The results showed that the Hb-MIP material developed here could selectively recognize and purify various Hb directly from either crude E. coli extracts or human body fluids, such as blood plasma and cerebrospinal fluid (CSF), in one-step. The dynamic binding capacity at 10% breakthrough was around 7.4 mg mL^-1resin for adult Hb (HbA) and fetal Hb (HbF). This chromatographic material also allowed identification of changes related to amino acid substitutions on the Hb protein surface. For instance, when an additional lysine residue was introduced, the HbA αY42K mutant eluted later in an Hb-MIP column than wildtype HbA. Additional negative charges on the protein surface, such as aspartate, mitigated the interaction between the protein and imprinted polymers, and therefore an αA19D-αA12D HbF mutant eluted earlier, at -2.7 column volumes compared to wildtype HbF.

Sensitive electrochemical detection of gp120 based on the combination of NBD-556 and gp120

As is known, the employment of molecular imprinting polymer (MIP) as specific sensing materials in sensors, namely MIP-based sensors. In this contribution, we devised a MIP electrochemical sensor for the detection of variable-format conformations protein gp120. The sensor was constructed by using a grapheme-like carbon nanfragment (CNF) and bismuth oxides composites (CNF-Bi) as decoration material, small-molecule entry inhibitor NBD-556 and gp120 conjugates NBD-556@gp120 instead of gp120 as the template, and pyrrole as an electropolymerization monomer. Cyclic voltammetry, differential pulse voltammetry, scanning electron microscopy and transmission electron microscope were used to characterize the preparation process of the sensor. Results showing that, under optimized conditions, the introduction of NBD-556 make the specific recognition and analytical properties of the MIP sensor towards gp120 more efficient. The response currents were proportional to the NBD-556@gp120 concentrations in the range of 0.0002 ng mL^-1 to 200 ng mL^-1 with the detection limit of 0.0003 ng mL^-1 based on S/N = 3. Meanwhile, the NBD-556@gp120 based MIP sensor also shows acceptable stability and reproducibility. When used for the detection of gp120 in human plasma, it also showed good accuracy. This research idea is in great promising for the early diagnosis of HIV-1 virus and can also be extended to the detection of other conformationally unstable proteins.

Polysiloxanes in Theranostics and Drug Delivery: A Review

One of the historical problems of medicine is that often, diagnosis and therapy do not interface, at best. Moreover, especially in some areas, such as oncology, the stress for the organism during the two phases (diagnosis and therapy) can become excessive, and be fatal to the success of the treatment. The extraordinary progress of nanotechnology in the last 25 years has offered the opportunity to build a nanoplatform able to ferry drugs, and loads onto them both imaging and therapeutic functions, thus creating nanosystems capable of diagnosis, drug delivery, and monitoring of therapeutic response. The purpose of this unusual, and up to recent times, unimaginable, marriage between diagnosis and therapeutics is the reaching of protocols more specific to individuals. The dual use of particles/device lead to a personalized medicine. Due to their biocompatibility, versatility, physical and chemical resistance, and ability to be functionalized, silica nanoparticles and polysiloxanes are the heart and the shield of this nanoplatform, respectively. In this short review, I analyze the applications of these silicon-based materials in the field of controlled drug delivery.

Preparation of Protein Molecular-Imprinted Polysiloxane Membrane Using Calcium Alginate Film as Matrix and Its Application for Cell Culture

Bovine serum albumin (BSA) molecular-imprinted polysiloxane (MIP) membrane was prepared by sol-gel technology, using silanes as the functional monomers, BSA as the template and CaAlg hydrogel film as the matrix. The stress-strain curves of wet CaAlg membrane and molecular-imprinted polysiloxane membrane were investigated. We evaluate the adsorption and recognition properties of MIP membrane. Results showed that the adsorption capacity of BSA-imprinted polysiloxane for BSA reached 28.83 mg/g, which was 2.18 times the non-imprinted polysiloxane (NIP) membrane. The adsorption rate was higher than that of the protein-imprinted hydrogel. BSA-imprinted polysiloxane membrane could identify the protein template from competitive proteins such as bovine hemoglobin, ovalbumin and bovine γ-globulin. In order to obtain the biomaterial that can promote cell adhesion and proliferation, fibronectin (FN)-imprinted polysiloxane (FN-MIP) membrane was obtained by using fibronectin as the template, silanes as functional monomers, and CaAlg hydrogel membrane as the substrate or matrix. The FN-MIP adsorbed more FN than NIP. The FN-imprinted polysiloxane membrane was applied to culture mouse fibroblast cells (L929) and the results proved that the FN-MIP had a better effect on cell adhesion than NIP.

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.

Separation of bovine hemoglobin using novel magnetic molecular imprinted nanoparticles

Magnetic molecular imprinted nanoparticles (MMIPs), combining the progressiveness of magnetic nanoparticles and surface molecular imprinting technology, have attracted increasing attention because of the high efficiency and specificity in isolation and enrichment of the target protein. This study focused on the preparation of bovine hemoglobin MMIPs with bovine hemoglobin (BHb) as the template protein and the molecular imprinted polymer covering the functional magnetic nanoparticles modified with silane and acrylic groups. The physicochemical characteristics as well as the dynamics and isothermal adsorption properties of the generated nanoparticles were investigated to determine their efficiency and specificity in the adsorption of target protein. The maximum adsorption of the target protein was 169.29 mg g⁻¹ at a specific pH, which was much larger than those obtained in some other research reports. MMIPs showed favorable selectivity towards BHb in a mixture of three different proteins. The results indicated the significant effects and broad prospects of MMIPs in the isolation and enrichment of specific proteins in the field of food, medicine and biological research.

Magnetic molecular imprinted nanoparticles (MMIPs), combining the progressiveness of magnetic nanoparticles and surface molecular imprinting technology, have shown the high efficiency and specificity in isolation and enrichment of the target protein.

Gas-stimuli-responsive molecularly imprinted polymer particles with switchable affinity for target protein

Molecularly imprinted polymer particles bearing gas-responsive property was successfully prepared using functional initiator.

Sensing platform for neuron specific enolase based on molecularly imprinted polymerized ionic liquids in between gold nanoarrays

A molecularly imprinted electrochemical sensor for neuron specific enolase (NSE) was developed by electrochemical polymerizing ionic liquid, which was functionalized with pyrrole moiety, in between gold nanoarrays. A well-defined 3D structured gold nanoarray was fabricated on a glassy carbon electrode (GCE) surface by using template-assisted electrochemical deposition technique. 1-(3-mercaptopropyl)-3-vinyl-imidazolium tetrafluoroborate was self-assembled onto the surface of gold nanoarrays to produce active sites for anchoring the molecularly imprinted film. Subsequently, an electrochemical polymerization procedure was carried out in an aqueous solution containing 1,3-di(3-N-pyrrolpropyl)imidazolium bromine ionic liquid and neuron specific enolase (NSE). After removing NSE templates, a molecularly imprinted sensor was successfully fabricated. The sensor showed high selectivity and sensitivity towards NSE, produced a linear response in the concentration range from 0.01 to 1.0ngmL^-1 and had a detection limit of 2.6pgmL^-1 with an incubation time of 15min. The developed sensor was demonstrated successful in determining NSE in clinical serum samples.

Thermal stability, storage and release of proteins with tailored fit in silica

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a "cold chain" of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica "cage", rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This "ensilication" method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the "cold chain" problem for biological materials, in particular for vaccines.

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.

Aromatic Functionality of Target Proteins Influences Monomer Selection for Creating Artificial Antibodies on Plasmonic Biosensors

Natural antibodies used as biorecognition elements suffer from numerous shortcomings, such as limited chemical and environmental stability and cost. Artificial antibodies based on molecular imprinting are an attractive alternative to natural antibodies. We investigated the role of aromatic interactions in target recognition capabilities of artificial antibodies. Three proteins with different aromatic amino acid content were employed as model targets. Artificial antibodies were formed on nanostructures using combinations of silane monomers of varying aromatic functionality. We employed refractive index sensitivity of plasmonic nanostructures as a transduction platform for monitoring various steps in the imprinting process and to quantify the target recognition capabilities of the artificial antibodies. The sensitivity of the artificial antibodies with aromatic interactions exhibited a protein-dependent enhancement. Selectivity and sensitivity enhancement due to the presence of aromatic groups in imprinted polymer matrix was found to be higher for target proteins with higher aromatic amino acid content. Our results indicate that tailoring the monomer composition based on the amino acid content of the target protein can improve the sensitivity of plasmonic biosensors based on artificial antibodies without affecting the selectivity.

A surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat for selective removal of bilirubin

Electrospinning and surface molecular imprinting were used together to prepare a surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat for selective removal of bilirubin.

Polythiophene nanofilms for sensitive fluorescence detection of viruses in drinking water

Molecular imprints of the tobacco necrosis virus (TNV) have been formed within polythiophene nanofilms with an approximate thickness of 200nm. These films have been electrochemically deposited onto conducting Au surfaces. Upon rebinding, the TNV-polythiophene complex changes the fluorescence intensity of the nanofilm. The fluorescence intensity at 410nm was observed to be proportional to the concentration of viruses in the range of 0.1-10ngL(-1) (0.15-15pg) with the lower calculated detection limit of 2.29ngL(-1) (3.4pg). The intensity of the fluorescence emission is not affected by the thickness of the polythiophene film and the nature of TNV specific binding sites. Kinetic data analyses showed that the nanofilm responds to TNV within 2min; and cross-selectivity studies with tobacco mosaic virus (TMV) showed an excellent specificity for the targeted TNV. These binding experiments demonstrate the potential of fluorescence emission for the specific, label free and rapid detection of viruses using nanofilm sensors. Taking into account the lower limit of detection, the fluorescence sensing reported here is reliable, simple to perform, rapid, cost-effective and offers a sensitive analytical method for virus detection in water resources.

Electrosynthesis and binding properties of molecularly imprinted poly-o-phenylenediamine for selective recognition and direct electrochemical detection of myoglobin

Electrosynthesis of molecularly imprinted polymer (MIP) templated with myoglobin (Mb) and the reference non-imprinted polymer (NIP) was examined with o-phenylenediamine (o-PD) as a monomer. Mass-sensitive quartz crystal microbalance with dissipation monitoring supplied by an electrochemical module (EQCM-D) was applied to characterize and optimize MIP/NIP electrosynthesis. Mb rebinding was detected by direct electrocatalytic reduction of Mb by square wave voltammetry (SWV) or differential pulse voltammetry (DPV). The results obtained showed high specificity of polymeric antibodies to template Mb, with an imprinting factor determined as a ratio Imax(MIP)/Imax(NIP) of 2-4. The prepared MIP sensor is characterized by an apparent dissociation constant of (3.3±0.5)×10(-9)M and has a broad range of working concentrations of 1nM-1μМ, with the detection limit of 0.5nM (9ng/ml). Mb rebinding was examined in Mb-free diluted human serum spiked with Mb as well as in plasma samples of patients with acute myocardial infarction (AMI) and in control plasma of healthy donors in order to demonstrate the potential medical application of developed MIP sensors.

Preparation and characterization of biocompatible molecularly imprinted poly(ionic liquid) films on the surface of multi-walled carbon nanotubes

A series of novel biocompatible MIPs were synthesized for BSA recognition by using MWCNTs with different outside diameters as substrates, and allyl-functionalized ionic liquids with different anion species as monomers.

Fluorescence signaling molecularly imprinted polymers for antibiotics prepared via site-directed post-imprinting introduction of plural fluorescent reporters within the recognition cavity

An antibiotic-imprinted cavity with two different fluorescent dyes was prepared by molecular imprinting and subsequent post-imprinting modifications (PIMs), for the readout of a specific binding event as a fluorescence signal.

Well-defined nanostructured surface-imprinted polymers for the highly selective enrichment of low-abundance protein in mammalian cell extract

A new approach for the adsorption and enrichment of natural low-abundance protein by using nanostructured surface-imprinted polymers is presented.

Monoclonal antibody capture from cell culture supernatants using epitope imprinted macroporous membranes

A straightforward epitope imprinting procedure is used to prepare IgG affinity membranes directly applicable to mAb capture under near process realistic conditions.

Fabrication of High-Performance Magnetic Lysozyme-Imprinted Microsphere and Its NIR-Responsive Controlled Release Property

The preparation of efficient and practical biomacromolecules imprinted polymer materials is still a challenging task because of the spatial hindrance caused by the large size of template and target molecules in the imprinting and recognition process. Herein, we provided a novel pathway to coat a NIR-light responsive lysozyme-imprinted polydopamine (PDA) layer on a fibrous SiO2 (F-SiO2) microsphere grown up from a magnetic Fe3O4 core nanoparticle. The magnetic core-shell structured lysozyme-imprinted Fe3O4@F-SiO2@PDA microspheres (MIP-lysozyme) can be easily separated by a magnet and have a high saturation adsorption capacity of lysozyme of 700 mg/g within 30 min because of the high surface area of 570 m(2)/g and the mesopore size of 12 nm of the Fe3O4@F-SiO2 support. The MIP-lysozyme microspheres also show an excellent selective adsorption of lysozyme (IF > 4). The binding thermodynamic parameters studied by ITC proves that the lysozyme should be restricted by the well-defined 3D structure of MIP-lysozyme microspheres. The MIP-lysozyme can extract lysozyme efficiently from real egg white. Owing to the efficient NIR light photothermal effect of PDA layer, the MIP-lysozyme microspheres show the controlled release property triggered by NIR laser. The released lysozyme molecules still maintain good bioactivity, which can efficiently decompose E. coli. Therefore, this work provides a novel strategy to build practical NIR-light-responsive MIPs for the extraction and application of biomacromolecules.

Antibody-like Biorecognition Sites for Proteins from Surface Imprinting on Nanoparticles

Natural antibodies are used widely for important applications such as biomedical analysis, cancer therapy, and directed drug delivery, but they are expensive and may have limited stability. This study describes synthesis of antibody-like binding sites by molecular imprinting on silica nanoparticles (SiNP) using a combination of four organosilane monomers with amino acid-like side chains providing hydrophobic, hydrophilic, and H-bonding interactions with target proteins. This approach provided artificial antibody (AA) nanoparticles with good selectivity and specificity to binding domains on target proteins in a relatively low-cost synthesis. The AAs were made by polymer grafting onto SiNPs for human serum albumin (HSA) and glucose oxidase (GOx). Binding affinity, selectivity, and specificity was compared to several other proteins using adsorption isotherms and surface plasmon resonance (SPR). The Langmuir-Freundlich adsorption model was used to obtain apparent binding constants (KLF) from binding isotherms of HSA (6.7 × 10(4)) and GOx (4.7 × 10(4)) to their respective AAs. These values were 4-300 fold larger compared to a series of nontemplate proteins. SPR binding studies of AAs with proteins attached to a gold surface confirmed good specificity and revealed faster binding for the target proteins compared to nontarget proteins. Target proteins retained their secondary structures upon binding. Binding capacity of AAHSA for HSA was 5.9 mg HSA/g compared to 1.4 mg/g for previously report imprinted silica beads imprinted with poly(aminophenyl)boronic acid. Also, 90% recovery for HSA spiked into 2% calf serum was found for AAHSA.

From imprinting to microcontact imprinting-A new tool to increase selectivity in analytical devices

Molecular imprinting technology has been successfully applied to small molecular templates but a slow progress has been made in macromolecular imprinting owing to the challenges in natural properties of macromolecules, especially proteins. In this review, the macromolecular imprinting approaches are discussed with examples from recent publications. A new molecular imprinting strategy, microcontact imprinting is highlighted with its recent applications.

Highly selective BSA imprinted polyacrylamide hydrogels facilitated by a metal-coding MIP approach

We report the fabrication of metal-coded molecularly imprinted polymers (MIPs) using hydrogel-based protein imprinting techniques. A Co(II) complex was prepared using (E)-2-((2 hydrazide-(4-vinylbenzyl)hydrazono)methyl)phenol; along with iron(III) chloroprotoporphyrin (Hemin), vinylferrocene (VFc), zinc(II) protoporphyrin (ZnPP) and protoporphyrin (PP), these complexes were introduced into the MIPs as co-monomers for metal-coding of non-metalloprotein imprints. Results indicate a 66% enhancement for bovine serum albumin (BSA) protein binding capacities (Q, mg/g) via metal-ion/ligand exchange properties within the metal-coded MIPs. Specifically, Co(II)-complex-based MIPs exhibited 92 ± 1% specific binding with Q values of 5.7 ± 0.45 mg BSA/g polymer and imprinting factors (IF) of 14.8 ± 1.9 (MIP/non-imprinted (NIP) control). The selectivity of our Co(II)-coded BSA MIPs were also tested using bovine haemoglobin (BHb), lysozyme (Lyz), and trypsin (Tryp). By evaluating imprinting factors (K), each of the latter proteins was found to have lower affinities in comparison to cognate BSA template. The hydrogels were further characterised by thermal analysis and differential scanning calorimetry (DSC) to assess optimum polymer composition.

STATEMENT OF SIGNIFICANCE

The development of hydrogel-based molecularly imprinted polymer (HydroMIPs) technology for the memory imprinting of proteins and for protein biosensor development presents many possibilities, including uses in bio-sample clean-up or selective extraction, replacement of biological antibodies in immunoassays and biosensors for medicine and the environment. Biosensors for proteins and viruses are currently expensive to develop because they require the use of expensive antibodies. Because of their biomimicry capabilities (and their potential to act as synthetic antibodies), HydroMIPs potentially offer a route to the development of new low-cost biosensors. Herein, a metal ion-mediated imprinting approach was employed to metal-code our hydrogel-based MIPs for the selective recognition of bovine serum albumin (BSA). Specifically, Co(II)-complex based MIPs exhibited a 66% enhancement (in comparison to our normal MIPs) exhibiting 92 ± 1% specific binding with Q values of 5.7 ± 0.45 mg BSA/g polymer and imprinting factors (IF) of 14.8 ± 1.9 (MIP/ non-imprinted (NIP) control). The proposed metal-coded MIPs for protein recognition are intended to lead to unprecedented improvement in MIP selectivity and for future biosensor development that rely on an electrochemical redox processes.

Review of the recent progress in photoresponsive molecularly imprinted polymers containing azobenzene chromophores

Photoresponsive molecularly imprinted polymers (PMIPs) containing azobenzene have received wide research attention in recent years and made notable achievements. This article reviews the recent developments on PMIPs containing azobenzene. Topics include the following: (i) brief introduction of azobenzene, molecularly imprinted polymers, and PMIPs containing azobenzene; (ii) progress in functional monomers, cross-linkers, and polymerization conditions; (iii) preparation methods, properties, applications, as well as advantages and disadvantages of conventional PMIPs; (iv) substrate, preparation method, and applications of photoresponsive surface molecularly imprinted polymers; and (v) some perspectives for further development of PMIPs containing azobenzene.

Selective glycoprotein detection through covalent templating and allosteric click-imprinting

A hierarchical bottom-up route exploiting reversible covalent interactions with boronic acids and so-called click chemistry for selective glycoprotein detection is described. The self-assembled and imprinted surfaces confer high binding affinities, nanomolar sensitivity, exceptional glycoprotein specificity and selectivity.

Many glycoproteins are intimately linked to the onset and progression of numerous heritable or acquired diseases of humans, including cancer. Indeed the recognition of specific glycoproteins remains a significant challenge in analytical method and diagnostic development. Herein, a hierarchical bottom-up route exploiting reversible covalent interactions with boronic acids and so-called click chemistry for the fabrication of glycoprotein selective surfaces that surmount current antibody constraints is described. The self-assembled and imprinted surfaces, containing specific glycoprotein molecular recognition nanocavities, confer high binding affinities, nanomolar sensitivity, exceptional glycoprotein specificity and selectivity with as high as 30 fold selectivity for prostate specific antigen (PSA) over other glycoproteins. This synthetic, robust and highly selective recognition platform can be used in complex biological media and be recycled multiple times with no performance decrement.

Preparation of molecularly imprinted polymers for the recognition of proteins via the generation of peptide-fragment binding sites by semi-covalent imprinting and enzymatic digestion

An acryloyl protein was copolymerized with a crosslinker, followed by enzymatic digestion, yielding protein imprinted polymers bearing peptide-fragment binding sites.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

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

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