Core-shell molecularly imprinted polymer nanoparticles with assistant recognition polymer chains for effective recognition and enrichment of natural low-abundance protein

A solid-phase fluorescence sensor for measuring chemical species in water

In this study, the first of its kind, a solid-phase fluorescence sensing platform was developed to quantify contaminants in water. ZnO quantum dots (QDs) were combined with molecularly imprinted polymers (MIPs) to form fluorescence sensing materials. Solid sensing layers were formed via a straightforward spin-coating method, which demonstrated a strong attachment to the sensor substrate while maintaining the integrity of the sensing materials. The developed sensing platform comprised a portable fluorescence detector to measure fluorescence intensity, instead of traditional fluorescence spectroscopy. The solid sensing platform was first tested with 2,4-dichlorophenoxyacetic acid (2,4-D), demonstrating high sensitivity (0.0233) and a very strong correlation (0.98) between the target molecule concentration and sensor signal. Further, the sensing platform was successfully adapted to measure a substance with a different molecular mass and chemical structure, the algae toxin microcystin-LR (MCLR); this demonstrated the sensor's versatility in quantifying target molecules. Tap water samples spiked with MCLR were also used to test the sensor's practical application. Finally, the working mechanism of the sensing platform was established, and the key information for using the sensor to measure various contaminants was determined. With its high performance, broad applicability, and ease of use, the developed platform provides a suitable basis for lab-on-chip image-based sensing devices for environmental monitoring.

Highly selective titanium (IV)-immobilized O-Phospho-L-tyrosine modified magnetic nanoparticles for the enrichment of intact phosphoproteins

Phosphorylation is one of the most important protein post-translational modifications, which possesses dramatic regulatory effects on the function of proteins. In consideration of the low abundance and low stoichiometry of phosphorylation and non-specific signal suppression, efficient capture of the phosphoproteins from complex biological samples is critical to meet the need of protein profiling. In this work, a facile preparation of titanium (IV)-immobilized O-Phospho-L-tyrosine modified magnetic nanoparticles were developed for the enrichment of intact phosphoproteins. The prepared magnetic nanoparticles were characterized by various instruments and had a spherical shape with an average diameter of 300 nm. The adsorption isotherms were investigated and the maximum capacity for β-casein was calculated to be 961.5 mg/g. Standard protein mixtures and biological samples (non-fat milk and human serum) were selected to test the enrichment performance. Sodium dodecyl sulfate-poly acrylamide gel electrophoresis analysis demonstrated the excellent enrichment performance with high selectivity. With the superparamagnetic property, titanium (IV)-immobilized O-Phospho-L-tyrosine modified magnetic nanoparticles were convenient for the practical application and clinical promotion, thus having a promising prospect in the field of phosphoprotein research. This article is protected by copyright. All rights reserved.

Graphene-Based Femtogram-Level Sensitive Molecularly Imprinted Polymer of SARS-CoV-2

Rapid distribution of viral-induced diseases and weaknesses of common diagnostic platforms for accurate and sensitive identification of infected people raises an urgent demand for the design and fabrication of biosensors capable of early detection of viral biomarkers with high specificity. Accordingly, molecularly imprinted polymers (MIPs) as artificial antibodies prove to be an ideal preliminary detection platform for specific identification of target templates, with superior sensitivity and detection limit (DL). MIPs detect the target template with the "lock and key" mechanism, the same as natural monoclonal antibodies, and present ideal stability at ambient temperature, which improves their practicality for real applications. Herein, a 2D MIP platform consisting of decorated graphene oxide with the interconnected complex of polypyrrole-boronic acid is developed that can detect the trace of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen in aquatic biological samples with ultrahigh sensitivity/specificity with DL of 0.326 and 11.32 fg mL^-1 using voltammetric and amperometric assays, respectively. Additionally, the developed MIP shows remarkable stability, selectivity, and accuracy toward detecting the target template, which paves the way for developing ultraspecific and prompt screening diagnostic configurations capable of detecting the antigen in 1 min or 20 s using voltammetric or amperometric techniques.

Capsule-like molecular imprinted polymer nanoparticles for targeted and chemophotothermal synergistic cancer therapy

Selective cancer cell targeting, controlled drug release, easy construction and multiple therapeutic modalities are some of the desirable characteristics of drug delivery systems. We designed and built simple capsule-like molecular imprinted polymer (MIP)-based nanoparticles for targeted and chemo-photothermal synergistic cancer therapy. Using dopamine (DA) as functional monomer, cross-linking agent as well as photo-thermal agent, ZIF-8 (zeoliticimidazolate framework-8) as drug carrier, epitope of EGFR (epidermal growth factor receptor) as template molecules, molecular imprinted polymer (MIP) drug carrier was constructed. The ability of MIP layer to bind to EGFR epitope endowed the MD (DOX@MIP) particles to recognize EGFR-overexpressing cancer cells, while the pH-responsiveness and photothermal conversion ability of PDA (polydopamine) achieved chemo-photothermal synergistic effects upon NIR irradiation. Taken together, the MD nanoparticles integrated cancer cell targeting recognition, intelligent drug release, biocompatibility and chemo-photothermal effects, and is therefore a promising tool for targeted cancer therapy with minimal toxicity to normal cells, as well as tumor imaging.

Construction of shape memorable imprinted cavities for protein recognition using oligo-l-lysine-based peptide crosslinker

Protein-imprinted polymers are artificial receptors capable of recognizing protein. They are highly promising for applications in important bio-related areas, however, their development was severely retarded by two problems: difficult template removal and low imprinting efficiency. The two problems could be overcome by constructing shape-memorable imprinted cavities using peptide crosslinker. Here a new oligo-l-lysine-based peptide crosslinker was designed and synthesized. A novel cytochrome c (Cyt C)-imprinted polymer was synthesized using the new peptide crosslinker. When switching pH between 12 and 7.4, the peptide segments incorporated in the polymer underwent reversible helix-coil transition. Because of the precise folding of the peptide segments, the imprinted cavities in the polymer could be enlarged when lowering pH to 7.4 to release the template protein, but restore their original size and shape at pH 12 to recognize the template protein. Therefore complete template removal was achieved under mild conditions. Meanwhile the imprinting efficiency was improved significantly. Compared to polymer crosslinked with the commonly used crosslinker N, N-methylenebisacrylamide, the imprinting efficiency of the peptide-crosslinked polymer was increased by 15 times. The new imprinted polymer presented not only a high adsorption capacity (454.4 mgg^-1), a high imprinting factor (6.3), high selectivity towards Cyt C, and excellent reusability, but also could preserve the fragile secondary structure of the eluted protein, and therefore had high potential in bioseparation. As a demonstration, Cyt C added into fetal bovine serum was separated from the sample using the polymer via a simple adsorption-desorption cycle. The recovery rate was as high as 92.7%.

Facile synthesis of titanium(IV) ion-immobilized arsenate-modified poly(glycidyl methacrylate) microparticles and the application to the specific enrichment of phosphoproteins

Selective separation and enrichment of phosphoproteins possess the distinct clinical and biological importance in the diagnosis, treatment, and management of several fatal human diseases. In this study, a facile synthesis of titanium(IV) ion-immobilized arsenate-modified poly(glycidyl methacrylate) microparticles (denoted as Ti⁴⁺-arsenate-PGMA-MPs) was developed for the efficient enrichment of intact phosphoproteins found in biologically complex protein samples. By virtue of the strong interaction between the titanium ions immobilized on the surface of Ti⁴⁺-arsenate-PGMA-MPs and phosphate groups of phosphoproteins, Ti⁴⁺-arsenate-PGMA-MPs had a high saturated adsorption capacity for phosphoproteins (901 mg/g for β-casein), which was much higher than that of non-phosphoproteins (73.5 mg/g for BSA). Ti⁴⁺-arsenate-PGMA-MPs were characterized by SEM, TEM, and FT-IR, and the average particle diameter was about 2.5 μm with good dispersibility. Besides, the application of Ti⁴⁺-arsenate-PGMA-MPs in real biological samples was investigated by SDS-PAGE analysis, and the results showed that Ti⁴⁺-arsenate-PGMA-MPs were able to enrich phosphoproteins efficiently.

Mesoporous molecularly imprinted polymer core@shell hybrid silica nanoparticles as adsorbent in microextraction by packed sorbent for multiresidue determination of pesticides in apple juice

In this work, we report the synthesis of a mesoporous molecularly imprinted polymer on the surface of silica nanoparticles (core@mMIP) to be applied as adsorbent in microextraction by packed sorbent (MEPS) for selective determination of pesticides in apple juice. The core@mMIP was properly characterized, showing good adhesion of the polymer to the silica core. The best extraction conditions were: 200 µL of ultrapure water as washing solvent, 150 µL of acetonitrile as eluent, 100 µL of sample at pH 2.5, five draw-eject cycles and 8 mg of adsorbent. Thereby, recoveries of 96.12 ± 1.05%, 76.88 ± 6.18% and 76.18 ± 5.57% were obtained for pyriproxyfen (PPX), deltamethrin (DTM) and etofenprox (ETF), respectively. After validation, the method presented linearity in the range of 0.02-10 µg mL^-1 (r > 0.99), limit of detection of 0.005 µg mL^-1, satisfactory selectivity, and proper precision and accuracy. The method was successfully applied real samples of processed and fresh apple juice.

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.

Core-Shell Molecularly Imprinted Polymer Nanocomposites for Biomedical and Environmental Applications

Core-shell polymers represent a class of composite particles comprising of minimum two dissimilar constituents, one at the center known as a core which is occupied by the other called shell. Core-shell molecularly imprinting polymers (CSMIPs) are composites prepared via printing a template molecule (analyte) in the coreshell assembly followed by their elimination to provide the everlasting cavities specific to the template molecules. Various other types of CSMIPs with a partial shell, hollow-core and empty-shell are also prepared. Numerous methods have been reported for synthesizing the CSMIPs. CSMIPs composites could develop the ability to identify template molecules, increase the relative adsorption selectivity and offer higher adsorption capacity. Keen features are measured that permits these polymers to be utilized in numerous applications. It has been developed as a modern technique with the probability for an extensive range of uses in selective adsorption, biomedical fields, food processing, environmental applications, in utilizing the plant's extracts for further applications, and sensors. This review covers the approaches of developing the CSMIPs synthetic schemes, and their application with special emphasis on uses in the biomedical field, food care subjects, plant extracts analysis and in environmental studies.

Facile synthesis of titanium(IV) ion-immobilized poly-glycidyl methacrylate microparticles functionalized with polyethylenimine and adenosine triphosphate for highly specific enrichment of intact phosphoproteins

In this study, a facile synthesis of the titanium(IV) ion-immobilized poly-glycidyl methacrylate microparticles functionalized with polyethylenimine and adenosine triphosphate was developed for efficient enrichment of intact phosphoproteins. The titanium(IV) ion-immobilized microparticles had higher saturated adsorption capacity for phosphoproteins (1217.6 mg/g for β-casein) than nonphosphoproteins (97.1 mg/g for bovine serum albumin) and the average particle diameter was about 1.4 μm with good dispersibility. In application, as demonstrated by SDS-PAGE, titanium(IV) ion-immobilized microparticles exhibited good performance in enriching intact phosphoproteins from standard protein mixtures of β-casein and bovine serum albumin with high specificity and selectivity. In addition, titanium(IV) ion-immobilized microparticles were also successfully applied in intact phosphoprotein enrichment from complex biological samples including nonfat milk, chicken egg white, and mouse heart tissue extract.

Facile synthesis of titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles for highly specific enrichment and analysis of intact phosphoproteins

Analysis of phosphoproteins always faces the challenge of low stoichiometry, which demands highly selective and efficient enrichment in the initial sample preparation. Here we report our synthesis of the novel titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles (Ti⁴⁺-ATP-NPs) for efficient enrichment of intact phosphoproteins. The average diameter of Ti⁴⁺-ATP-NPs was about 128 nm with good dispersibility and the saturated adsorption capacity for β-casein was 1046.5 mg/g. In addition, Ti⁴⁺-ATP-NPs exhibited high specificity and selectivity in enriching phosphoproteins from both standard protein mixtures and complex biological samples (non-fat milk, chicken egg white and mouse heart tissue extract) as demonstrated by SDS-PAGE.

Current Progress of Nanomaterials in Molecularly Imprinted Electrochemical Sensing

Nanomaterials have received much attention during the past decade because of their excellent optical, electronic, and catalytic properties. Nanomaterials possess high chemical reactivity, also high surface energy. Thus, provide a stable immobilization platform for biomolecules, while preserving their reactivity. Due to the conductive and catalytic properties, nanomaterials can also enhance the sensitivity of molecularly imprinted electrochemical sensors by amplifying the electrode surface, increasing the electron transfer, and catalyzing the electrochemical reactions. Molecularly imprinted polymers that contain specific molecular recognition sites can be designed for a particular target analyte. Incorporating nanomaterials into molecularly imprinted polymers is important because nanomaterials can improve the response signal, increase the sensitivity, and decrease the detection limit of the sensors. This study describes the classification of nanomaterials in molecularly imprinted polymers, their analytical properties, and their applications in the electrochemical sensors. The progress of the research on nanomaterials in molecularly imprinted polymers and the application of nanomaterials in molecularly imprinted polymers is also reviewed.

Novel Synthesis of Core-Shell Silica Nanoparticles for the Capture of Low Molecular Weight Proteins and Peptides

Silica nanoparticles were functionalized with immobilized molecular bait, Cibacron Blue, and a porous polymeric bis-acrylamide shell. These nanoparticles represent a new alternative to capture low molecular weight (LMW) proteins/peptides, that might be potential biomarkers. Functionalized core-shell silica nanoparticles (FCSNP) presented a size distribution of 243.9 ± 11.6 nm and an estimated surface charge of −38.1 ± 0.9 mV. The successful attachment of compounds at every stage of synthesis was evidenced by ATR-FTIR. The capture of model peptides was determined by mass spectrometry, indicating that only the peptide with a long sequence of hydrophobic amino acids (alpha zein 34-mer) interacted with the molecular bait. FCSNP excluded the high molecular weight protein (HMW), BSA, and captured LMW proteins (myoglobin and aprotinin), as evidenced by SDS-PAGE. Functionalization of nanoparticles with Cibacron Blue was crucial to capture these molecules. FCSNP were stable after twelve months of storage and maintained a capacity of 3.1–3.4 µg/mg.

Protein-Imprinted Polymers: The Shape of Things to Come?

The potential to develop materials with antibody-like molecular recognition properties has helped sustain interest in protein-imprinted polymers over the past several decades. Unfortunately, despite persistent research, the field of noncovalent protein imprinting has seen limited success in terms of achieving materials with high selectivity and high affinity. In this Perspective, important yet sometimes overlooked aspects of the imprinting and binding processes are reviewed to help understand why there has been limited success. In particular, the imprinting and binding processes are viewed through the scope of free radical polymerization and hydrogel swelling theories to underscore the complexity of the synthesis and behavior of protein-imprinted polymers. Additionally, we review the metrics of success commonly used in protein imprinting literature (i.e., adsorption capacity, imprinting factor, and selectivity factor) and consider the relevance of each to the characterization of an imprinted polymer's recognition characteristics. Throughout, common shortcomings are highlighted, and experiments that could help verify or disprove the efficacy of noncovalent protein imprinting are discussed.

Bio-inspired virus imprinted polymer for prevention of viral infections

A novel virus-imprinted polymer for prevention of viral infection was prepared by anchoring molecularly imprinted polymer (MIP) on the surface of poly-dopamine (PDA)-coated silica particles. The imprinting reaction was carried out via self-polymerization of dopamine in the presence of a virus template. Plaque forming assay indicated that the MIP exhibited selective anti-viral infection properties for the template virus in complex media containing different interfering substances, and even other types of viruses. Remarkable dose-dependent and time-dependent inhibition of virus infection was observed due to the MIP's selective binding to the template virus. When the MIP was incubated with the virus and host cells together, rapid and selective adsorption of template viruses by the MIP prevented the viruses to infect the host cells in a period of 12h. The MIP was biocompatible and non-toxic, and had excellent stability and reusability. Furthermore, the MIPs prepared using different viruses as templates showed similar anti-viral infection properties. The MIP synthesized using dopamine as monomer and crude virus as template provided an attractive possibility for clinical applications in the field of antiviral therapy.

STATEMENT OF SIGNIFICANCE

This is the first report to prepare artificial antibody (molecularly imprinted polymer, MIP) that can selectively prevent virus infection using dopamine self-polymerization system. Only MIP anchoring on the surface of poly-dopamine coated silica particles and polymerized using ammonium persulfate as radical initiator showed dose-dependent and time-dependent inhibition of template virus infection in complex media containing interferences and even other viruses. Viruses bond to MIP lost infectious capability. When incubated with virus and host cells, MIP rebond viruses rapidly and selectively to prevent viruses infecting host cells for 12h. The achieved MIPs were biocompatibility, non-toxicity with excellent stability and reusability, and can be used to different viruses. The bio-mimic MIPs provided an attractive prospect for clinical applications in antiviral therapy.

A highly selective protein adsorber via two-step surface-initiated molecular imprinting utilizing a multi-functional polymeric scaffold on a macroporous cellulose membrane

Protein-imprinted cellulose membranes with tailored binding selectivity have been prepared by two-step surface grafting based on an orthogonal photochemical initiation.

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.

Molecularly imprinted polymers for separating and sensing of macromolecular compounds and microorganisms

The present review article focuses on gathering, summarizing, and critically evaluating the results of the last decade on separating and sensing macromolecular compounds and microorganisms with the use of molecularly imprinted polymer (MIP) synthetic receptors. Macromolecules play an important role in biology and are termed that way to contrast them from micromolecules. The former are large and complex molecules with relatively high molecular weights. The article mainly considers chemical sensing of deoxyribonucleic acids (DNAs), proteins and protein fragments as well as sugars and oligosaccharides. Moreover, it briefly discusses fabrication of chemosensors for determination of bacteria and viruses that can ultimately be considered as extremely large macromolecules.

Recent advances in applications of nanomaterials for sample preparation

Sample preparation is a key step for qualitative and quantitative analysis of trace analytes in complicated matrix. Along with the rapid development of nanotechnology in material science, numerous nanomaterials have been developed with particularly useful applications in analytical chemistry. Benefitting from their high specific areas, increased surface activities, and unprecedented physical/chemical properties, the potentials of nanomaterials for rapid and efficient sample preparation have been exploited extensively. In this review, recent progress of novel nanomaterials applied in sample preparation has been summarized and discussed. Both nanoparticles and nanoporous materials are evaluated for their unusual performance in sample preparation. Various compositions and functionalizations extended the applications of nanomaterials in sample preparations, and distinct size and shape selectivity was generated from the diversified pore structures of nanoporous materials. Such great variety make nanomaterials a kind of versatile tools in sample preparation for almost all categories of analytes.

Artificial chaperones based on mixed shell polymeric micelles: insight into the mechanism of the interaction of the chaperone with substrate proteins using Förster resonance energy transfer

Controlled and reversible interactions between polymeric nanoparticles and proteins have gained more and more attention with the hope to address many biological issues such as prevention of protein denaturation, interference of the fibrillation of disease relative proteins, removing of toxic biomolecules as well as targeting delivery of proteins, etc. In such cases, proper analytic techniques are needed to reveal the underlying mechanism of the particle-protein interactions. In the current work, Förster Resonance Energy Transfer (FRET) was used to investigate the interaction of our tailor designed artificial chaperone based on mixed shell polymeric micelles (MSPMs) with their substrate proteins. We designed a new kind of MSPMs with fluorescent acceptors precisely placed at the desired locations as well as hydrophobic domains which can adsorb unfolded proteins with a propensity to aggregate. Interactions of such model micelles with a donor-labeled protein-FITC-lysozyme, was monitored by FRET. The fabrication strategy of MSPMs makes it possible to control the accurate location of the acceptor, which is critical to reveal some unexpected insights of the micelle-protein interactions upon heating and cooling. Preadsorption of native proteins onto the hydrophobic domains of the MSPMs is a key step to prevent thermo-denaturation by diminishing interprotein aggregations. Reversible protein adsorption during heating and releasing during cooling have been confirmed. Conclusions from the FRET effect are in line with the measurement of residual enzymatic activity.

An effective way to imprint protein with the preservation of template structure by using a macromolecule as the functional monomer

A novel strategy of using a macromolecular functional monomer to stabilize and imprint protein was proposed for the first time.