Surface protein imprinted core-shell particles for high selective lysozyme recognition prepared by reversible addition-fragmentation chain transfer strategy

Electrochemical and thermal detection of allergenic substance lysozyme with molecularly imprinted nanoparticles

Lysozyme (LYZ) is a small cationic protein which is widely used for medical treatment and in the food industry to act as an anti-bacterial agent; however, it can trigger allergic reactions. In this study, high-affinity molecularly imprinted nanoparticles (nanoMIPs) were synthesized for LYZ using a solid-phase approach. The produced nanoMIPs were electrografted to screen-printed electrodes (SPEs), disposable electrodes with high commercial potential, to enable electrochemical and thermal sensing. Electrochemical impedance spectroscopy (EIS) facilitated fast measurement (5-10 min) and is able to determine trace levels of LYZ (pM) and can discriminate between LYZ and structurally similar proteins (bovine serum albumin, troponin-I). In tandem, thermal analysis was conducted with the heat transfer method (HTM), which is based on monitoring the heat transfer resistance at the solid-liquid interface of the functionalized SPE. HTM as detection technique guaranteed trace-level (fM) detection of LYZ but needed longer analysis time compared to EIS measurement (30 min vs 5-10 min). Considering the versatility of the nanoMIPs which can be adapted to virtually any target of interest, these low-cost point-of-care sensors hold great potential to improve food safety.

A Fusion of Molecular Imprinting Technology and Siloxane Chemistry: A Way to Advanced Hybrid Nanomaterials

Molecular imprinting technology is a well-known strategy to synthesize materials with a predetermined specificity. For fifty years, the "classical" approach assumed the creation of "memory sites" in the organic polymer matrix by a template molecule that interacts with the functional monomer prior to the polymerization and template removal. However, the phenomenon of a material's "memory" provided by the "footprint" of the chemical entity was first observed on silica-based materials nearly a century ago. Through the years, molecular imprinting technology has attracted the attention of many scientists. Different forms of molecularly imprinted materials, even on the nanoscale, were elaborated, predominantly using organic polymers to induce the "memory". This field has expanded quickly in recent years, providing versatile tools for the separation or detection of numerous chemical compounds or even macromolecules. In this review, we would like to emphasize the role of the molecular imprinting process in the formation of highly specific siloxane-based nanomaterials. The distinct chemistry of siloxanes provides an opportunity for the facile functionalization of the surfaces of nanomaterials, enabling us to introduce additional properties and providing a way for vast applications such as detectors or separators. It also allows for catalyzing chemical reactions providing microreactors to facilitate organic synthesis. Finally, it determines the properties of siloxanes such as biocompatibility, which opens the way to applications in drug delivery and nanomedicine. Thus, a brief outlook on the chemistry of siloxanes prior to the discussion of the current state of the art of siloxane-based imprinted nanomaterials will be provided. Those aspects will be presented in the context of practical applications in various areas of chemistry and medicine. Finally, a brief outlook of future perspectives for the field will be pointed out.

Development of Silica Nanoparticle Supported Imprinted Polymers for Selective Lysozyme Recognition

Protein imprinted MIPs show notable potential for applications in many analytical areas such as clinical analysis, medical diagnostics and environmental monitoring, but also in drug delivery scenarios. In this study, we present various modifications of two different synthesis routes to create imprinted core-shell particles serving as a synthetic recognition material for the protein hen egg white (HEW) lysozyme. HEW lysozyme is used as food additive E 1105 for preservation due to its antibacterial effects. For facilitating quality and regulatory control analysis in food matrices, it is necessary to apply suitable isolation methods as potentially provided by molecularly imprinted materials. The highest binding capacity achieved herein was 58.82 mg/g with imprinting factors ranging up to 2.74, rendering these materials exceptionally suitable for selectively isolating HEW lysozyme.

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.

Imprinted Fluorescent Cellulose Membranes for the On-Site Detection of Myoglobin in Biological Media

In this work, the conjugation of molecularly imprinted polymers (MIPs) to quantum dots (QDs) was successfully applied in the assembly of an imprinted cellulose membrane [hydroxy ethyl cellulose (HEC)/MIP@QDs] for the specific recognition of the cardiac biomarker myoglobin (Myo) as a sensitive, user-friendly, and portable system with the potential for point-of-care (POC) applications. The concept is to use the MIPs as biorecognition elements, previously prepared on the surface of semiconductor cadmium telluride QDs as detection particles. The fluorescent quenching of the membrane occurred with increasing concentrations of Myo, showing linearity in the interval range of 7.39-291.3 pg/mL in a1000-fold diluted human serum. The best membrane showed a linear response below the cutoff values for myocardial infarction (23 ng/mL), a limit of detection of 3.08 pg/mL, and an imprinting factor of 1.65. The incorporation of the biorecognition element MIPs on the cellulose substrate brings an approach toward a portable and user-friendly device in a sustainable manner. Overall, the imprinted membranes display good stability and selectivity toward Myo when compared with the nonimprinted membranes (HEC/NIP@QDs) and have the potential to be applied as a sensitive system for Myo detection in the presence of other proteins. Moreover, the conjugation of MIPs to QDs increases the sensitivity of the system for an optical label-free detection method, reaching concentration levels with clinical significance.

Synthesis, parameters, properties and applications of responsive molecularly imprinted microgels: a review

Responsive molecularly imprinted microgels (MIGs) have gained a lot of interest due to their responsive specificity and selectivity for target compounds. Study on MIGs is rapidly increasing due to their quick responsive behavior in various stimuli like pH and temperature. MIGs show unique property of morphology control on in-situ synthesis of nanoparticles in response of variation in reactant concentration. Literature related to synthesis, parameters, characterization, applications and prospects of MIGs are critically reviewed here. Range of templates, monomers, initiators and crosslinkers are summarized for designing of desired MIGs. This review article describes effect of variation in reactants combination and composition on morphology, imprinting factor and percentage yield of MIGs. Hydrolysis of similar templates using MIGs is also described. Relation between percentage hydrolysis and hydrolysis time of targets at different temperatures and template:monomer ratio is also analyzed. Possible imprinting modes of ionic/non-ionic templates and its series are also generalized on the basis of previous literature. MIGs are investigated as efficient anchoring vehicles for adsorption, catalysis, bio-sensing, drug delivery, inhibition and detection.

Synthesis of a molecularly imprinted polymer using MOF-74(Ni) as matrix for selective recognition of lysozyme

A molecularly imprinted polymer and metal organic framework were combined to prepare protein imprinted material. MOF-74(Ni) was used as a matrix to prepare surface-imprinted material with lysozyme as a template and polydopamine as an imprinting polymer. MOF-74(Ni) not only provides a large surface area (150.0 m²/g) to modify the polymer layer with more recognition sites (Wt (Ni) = 42.24%), but also facilitates the immobilization of lysozyme by using the chelation between Ni²⁺ of the MOF-74(Ni) and protein. The thin polydopamine layer (10 nm) of the molecularly imprinted material (named MOF@PDA-MIP) enables surface imprinting. Benefiting from the thin polymer layer, MOF@PDA-MIP reached adsorption equilibrium within 10 min. The maximum adsorption capacity reaches 313.5 mg/g with the highest imprinting factor (IF) of 7.8. The specific recognition sites can distinguish target lysozyme from other proteins such as egg albumin (OVA), bovine serum albumin (BSA) and ribonuclease A (RNase A). The material was successfully applied to separation of lysozyme from egg white. Graphical abstract.

Reasonable design and sifting of microporous carbon nanosphere-based surface molecularly imprinted polymer for selective removal of phenol from wastewater

Highly selective surface molecularly imprinted polymer (SMIP) was prepared on glucose-derived microporous carbon nanospheres (GMCNs) by surface molecular imprinting technology for the removal of phenol from wastewater. GMCNs with rich pore structure and surface oxygenic functional groups were adopted as support materials, on which the active layers were constructed by grafting silane coupling agent 3-(methacryloyloxy) propyltrimethoxysilane. Then with phenol as template molecule, different types and amounts of functional monomer (including methacrylic acid and 4-vinylpyridine (4-VP)) were screened for optimizing imprinting conditions suitable for phenol adsorption, and a series of SMIP was obtained through crosslinking polymerization. The adsorption behaviors of SMIP were evaluated by UV spectrophotometry. The results show that, when 4-VP is used as functional monomer, the resultant 4-VP/SMIP exhibites an excellent adsorption capacity of 85.72 mg g^-1. The relative selectivity factor for phenol against hydroquinone, p-nitrophenol and p-tert-butylphenol is 8.38, 7.96 and 6.67, respectively, indicating outstanding adsorption capacity and selectivity of 4-VP/SMIP. The pseudo-second-order model and Langmuir‒Freundlich model fit better than other models for the adsorption of phenol. 4-VP/SMIP is promising for selective removal and enrichment recovery towards phenol in wastewater.

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.

Controlled synthesis of PEGylated surface protein-imprinted nanoparticles

High recognition selectivity has been the main object in developing protein-imprinted materials. Here, we demonstrate a novel strategy for the controlled synthesis of PEGylated surface protein-imprinted nanoparticles with reduced nonspecific binding, which is based on sequential two steps of surface-initiated reversible addition-fragmentation chain transfer aqueous precipitation polymerization (SI-RAFT APP). Click chemistry was employed to construct hydrophilic nanocores with both high-density RAFT chain transfer agents and template-capturing groups. Through the first-step SI-RAFT APP, protein-imprinted nanoshells were formed over the nanocores using lysozyme as a model template. By the second-step SI-RAFT APP, nonlinear PEG chains were grafted from the core-shell imprinted nanoparticles before the removal of the template. Both the thickness of the imprinted nanoshells and the length of the grafted chains could be readily controlled by the polymerization time. Thus the obtained PEGylated core-shell particles exhibited greatly improved template binding selectivity compared with the non-PEGylated controls, typically with the imprinting factor increasing from 2.1 to 9.1. Meanwhile, the PEGylation process did not impair but significantly enhance the protein binding capacity. The generality of the established approach was preliminarily proved by imprinting another template protein, bovine hemoglobin. This work represents the first example for the controlled synthesis and post-imprinting functionalization of surface protein-imprinted nanoparticles via SI-RAFT polymerization.

Orthogonal dual molecularly imprinted polymer-based plasmonic immunosandwich assay: A double characteristic recognition strategy for specific detection of glycoproteins

Sensitive and specific detection methods are critical to the detection of glycoproteins. Immunoassay has been a powerful tool for this purpose, in which antibodies or their mimics particularly molecularly imprinted polymers (MIPs) are used for specific recognition. Epitope and glycan are two structure features of a glycoprotein. However, immunoassays based on simultaneous recognition towards the two characteristics have been scarcely explored so far. Herein we present a new strategy called orthogonal dual molecularly imprinted polymer-based plasmonic immunosandwich assay (odMIP-PISA). It relies on double recognition towards a target glycoprotein by two different types of MIPs, using epitope-imprinted gold nanoparticles (AuNPs)-coated slide as capturing substrate to recognize the peptide epitope and glycans-imprinted Raman-active silver nanoparticles as labeling nanotags to recognize the glycans. Carcinoembryonic antigen (CEA), a routinely used marker for colon cancer, was used as a test glycoprotein. The orthogonal double recognition apparently improved the specificity, reducing the maximum cross-reactivity from 14.4% for epitope recognition and 15.2% for glycan recognition to 8.2% for double recognition. Meanwhile, the plasmonic nanostructure-based Raman detection provided ultrahigh sensitivity, yielding a limit of detection of 5.56 × 10^-14 M (S/N = 10). Through measuring the CEA level in human serum, this method permitted differentiation of colon cancer patient from healthy individual. Compared with the traditional immunoassay, odMIP-PISA exhibited multiple advantages, including simplified procedure (6 steps), speed (30 min), reduced cost, and so on. Therefore, this new approach holds great promise in many applications particularly clinical diagnosis.

Ni2+-BSA Directional Coordination-Assisted Magnetic Molecularly Imprinted Microspheres with Enhanced Specific Rebinding to Target Proteins

Protein imprinting technology is of interest in drug delivery, biosensing, solid-phase extraction, and so forth. However, the efficient recognition and separation of proteins have remained challenging to date. Toward this, under the assistance of Ni²⁺-bovine serum albumin (BSA) directional coordination strategy, magnetic BSA-imprinted materials had been synthesized via dopamine self-polymerization on hollow Fe₃O₄@mSiO₂ microspheres (mSiO₂ referred as mesoporous silica). The well-defined imprinted microspheres possessed more satisfactory adsorption capacity (266.99 mg/g), enhanced imprinting factor (5.45), and fast adsorption saturation kinetics (40 min) for BSA, superior to many previous reports. Benefiting from the coordinate interaction between Ni²⁺ and BSA, these fabricated microspheres exhibited excellent specificity not only in individual and competitive protein rebinding samples but also in bovine serum. Combined with the directional coordination method, the magnetic-imprinted composite materials to selectively capture target proteins could provide promising potential in applications.

Bacteria assisted protein imprinting in sol-gel derived films

A hierarchical imprinting strategy was used to create protein imprints in a silicate film with a high binding capacity as well as selectivity toward the imprint protein and little specificity towards other proteins. In the first part of this work, rod-shaped bacteria were used as templates to create imprints in silica films of various thicknesses to open up the silica framework and increase the surface area exposed to solution. In the second part, the protein (e.g., cytochrome c (CYC) or green fluorescent protein (GFP)) was covalently attached to the surface of Bacillus subtilis and this protein-bacteria complex served as the imprint moiety. Atomic force microscopy and scanning electron microscopy were used to image the micron-size rod-shaped bacteria imprints formed on the silica surface. Fluorescence microscopy, which was used to follow the fabrication process with GFP as the representative protein, clearly demonstrated protein imprinting, protein removal and protein rebinding as well as protein specificity. Visible absorption spectroscopy using CYC as the imprint protein demonstrated relatively fast uptake kinetics and also good specificity against other proteins including bovine serum albumin (BSA), horseradish peroxidase (HRP), glucose oxidase (GOD), and lysozyme (LYZ). Collectively this work demonstrates a new surface bio-imprinting approach that generates recognition sites for proteins and provides a viable means to increase the binding capacity of such imprinted thin films.

Integrated ion imprinted polymers-paper composites for selective and sensitive detection of Cd(II) ions

Paper-based sensor is a new alternative technology to develop a portable, low-cost, and rapid analysis system in environmental chemistry. In this study, ion imprinted polymers (IIPs) using cadmium ions as the template were directly grafted on the surface of low-cost print paper based on the reversible addition-fragmentation chain transfer polymerization. It can be applied as a recognition element to selectively capture the target ions in the complex samples. The maximum adsorption capacity of IIPs composites was 155.2mgg^-1 and the imprinted factor was more than 3.0. Then, IIPs-paper platform could be also applied as a detection element for highly selective and sensitive detection of Cd(II) ions without complex sample pretreatment and expensive instrument, due to the selective recognition, formation of dithizone-cadmium complexes and light transmission ability. Under the optimized condition, the linear range was changed from 1 to 100ngmL^-1 and the limit of detection was 0.4ngmL^-1. The results were in good agreement with the classic ICP-MS method. Furthermore, the proposed method can also be developed for detection of other heavy metals by designing of new IIPs.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

RAFT polymerization to form stimuli-responsive polymers

Stimuli-responsive polymers respond to a variety of external stimuli, which include optical, electrical, thermal, mechanical, redox, pH, chemical, environmental and biological signals. This paper is concerned with the process of forming such polymers by RAFT polymerization.

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.

Thermoresponsive Epitope Surface-Imprinted Nanoparticles for Specific Capture and Release of Target Protein from Human Plasma

Among various artificial antibodies, epitope imprinted polymer has been paid increasingly attention. To modulate the "adsorption and release" behavior by environment stimuli, N-isopropylacrylamide, was adopted to fabricate the thermoresponsive epitope imprinted sites. The prepared imprinted materials could adsorb 46.6 mg/g of target protein with the imprinting factor of 4.0. The template utilization efficiency could reach as high as 8.21%. More importantly, in the real sample, the materials could controllably capture the target protein from the human plasma at 45 °C and release it at 4 °C, which demonstrated the "on-demand" application potentials of such materials in the biomolecule recognition field.

Functional Interfaces Constructed by Controlled/Living Radical Polymerization for Analytical Chemistry

The high-value applications of functional polymers in analytical science generally require well-defined interfaces, including precisely synthesized molecular architectures and compositions. Controlled/living radical polymerization (CRP) has been developed as a versatile and powerful tool for the preparation of polymers with narrow molecular weight distributions and predetermined molecular weights. Among the CRP system, atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) are well-used to develop new materials for analytical science, such as surface-modified core-shell particles, monoliths, MIP micro- or nanospheres, fluorescent nanoparticles, and multifunctional materials. In this review, we summarize the emerging functional interfaces constructed by RAFT and ATRP for applications in analytical science. Various polymers with precisely controlled architectures including homopolymers, block copolymers, molecular imprinted copolymers, and grafted copolymers were synthesized by CRP methods for molecular separation, retention, or sensing. We expect that the CRP methods will become the most popular technique for preparing functional polymers that can be broadly applied in analytical chemistry.

Molecularly imprinted plasmonic nanosensor for selective SERS detection of protein biomarkers

Molecularly imprinted plasmonic nanosensor has been prepared via the rational design of an ultrathin polymer layer on the surface of gold nanorods imprinted with the target protein. This nanosensor enabled selective fishing-out of the target protein biomarker even from a complex real sample such as human serum. Sensitive SERS detection of the protein biomarkers with a strong Raman enhancement was achieved by formation of protein imprinted gold nanorods aggregates, stacking of protein imprinted gold nanorods onto a glass plate, or self-assembly of protein imprinted gold nanorods into close-packed array. High specificity and sensitivity of this method were demonstrated with a detection limit of at least 10(-8)mol/L for the target protein. This could provide a promising alternative for the currently used immunoassays and fluorescence detection, and offer an ultrasensitive, non-destructive, and label-free technique for clinical diagnosis applications.

"Click on the bidirectional switch": the aptasensor for simultaneous detection of lysozyme and ATP with high sensitivity and high selectivity

A bifunctional and simple aptasensor was designed to one-spot simultaneously detect two analytes, lysozyme and ATP. The aptasensor was obtained by the electronic interaction between methyl violet (MV) and dsDNA. The dsDNA was obtained by hybridization of ATP aptamer and lysozyme aptamer. And we used the resonance light scattering (RLS) technique to detect the concentration of lysozyme and ATP. During the procedure of detection, the aptasensor works like a bidirectional switch, the corresponding side of the dsDNA will open when the target (lysozyme or ATP) "click" the aptamer, which results in corresponding RLS signal change. By the combination of the RLS technique, it is found that the changed RLS intensity was proportional to the concentration of lysozyme and ATP. The mixtures of ATP and lysozyme also met two binary function relations. The results indicated that the aptasensor could achieve simultaneous detection of ATP and lysozyme, the detection limits of ATP and lysozyme could reach 10(-11) M and 10(-12) M, respectively. The aptasensor shows potential application for small molecule and protein detection by RLS, it could extend the application of RLS technique.

Epitope imprinting enhanced IMAC (EI-IMAC) for highly selective purification of His-tagged protein

Selectivity of epitope imprinted sites is introduced on the IMAC surface through epitope surface imprinting. The obtained epitope imprinting enhanced IMAC (EI-IMAC) could purify His-tagged proteins with high selectivity without any major interference from the host proteins.

Surface molecularly imprinted polymers grafted on ordered mesoporous carbon nanospheres for fuel desulfurization

By adopting OMCNS as a carrier, the corresponding desulfurization adsorbent SMIP/OMCNS possesses excellent adsorption capacity and selectivity towards DBT.

Surface protein imprinted magnetic nanoparticles for specific recognition of bovine hemoglobin

Magnetic molecular imprinting for recognition of bovine hemoglobin was prepared by combining the surface imprinting technique with two-stage core–shell sol–gel polymerization.

Recent Advances in Macromolecularly Imprinted Polymers by Controlled Radical Polymerization Techniques

Molecularly imprinted polymers (MIPs) are synthetic receptors with tailor-made recognition sites for the target molecules. Their high molecular recognition ability, good stability, easy preparation, and low cost make them highly promising substitutes for biological receptors. Recent years have witnessed rapidly increasing interest in the imprinting of biomacromolecules and especially proteins because of the great potential of these MIPs in such applications as proteome analysis, clinical diagnostics, and biomedicine. So far, some useful strategies have been developed for the imprinting of proteins and controlled radical polymerization techniques have proven highly versatile for such purpose. This mini-review describes recent developments in the controlled preparation of proteins-imprinted polymers via such advanced polymerization techniques.