Core-Shell Magnetic Imprinted Polymers for the Recognition of FLAG-Tagpeptide

FLAG^® tag (DYKDDDDK) is a small epitope peptide employed for the purification of recombinant proteins such as immunoglobulins, cytokines, and gene regulatory proteins. It provides superior purity and recoveries of fused target proteins when compared to the commonly used His-tag. Nevertheless, the immunoaffinity-based adsorbents required for their isolation are far more expensive than the ligand-based affinity resin used in combination with the His-tag. In order to overcome this limitation we report herein the development of molecularly imprinted polymers (MIPs) selective to the FLAG^® tag. The polymers were prepared by the epitope imprinting approach using a four amino acids peptide, DYKD, including part of the FLAG^® sequence as template molecule. Different kinds of magnetic polymers were synthesised in aqueous and organic media also using different sizes of magnetite core nanoparticles. The synthesised polymers were used as solid phase extraction materials with excellent recoveries and high specificity for both peptides. The magnetic properties of the polymers confer a new, effective, simple, and fast method in the purification using FLAG^® tag.

Multi-stimuli responsive molecularly imprinted nanoparticles with tailorable affinity for modulated specific recognition of human serum protein

A kind of novel multi-stimuli responsive molecularly imprinted polymers with bovine serum protein (BSA) as dummy template (MSR-BSA-MIPs) was fabricated for specific recognition of human serum protein (HSA) with modulated...

Pyrrolidinyl ligand motif-assisted bovine serum albumin molecularly imprinted polymers with high specificity

Ideal binding ligands for anchoring proteins are essential for the design and assembly of desirable molecularly imprinted polymers (MIPs). In this study, bovine serum albumin-MIPs (BSA-MIPs) were successfully prepared by orchestrating the involvement of orientation-controllable binding ligands via sequential thiol-ene click and thiol-ene-amine conjugation. We showed that the optimal thiol-ene-amine conjugates and binding ligands were decisive in determining the rebinding capacity and selectivity. The pyrrolidinyl MIPs exhibited the best adsorption capacity of 352 ± 22 mg/g and a superior imprinting factor of 4.72 among MIPs with various binding ligands. These favourable results were further studied by computational simulation and isothermal titration calorimetry (ITC). Molecular docking revealed the preferential binding free energy and H-bonds between BSA residues and the thiol-ene-amine conjugates. Meanwhile, the pyrrolidinyl ligand motif enabled entropy-favourable affinity to be achieved via hydrophobic effects with the BSA template by ITC thermodynamics. Because of these favourable bindings, the MIPs exhibited excellent adsorption specificity to BSA over competing proteins. The proof-of-concept of MIPs with orientation-controllable conjugates and proven binding ligands for target proteins demonstrates that this material is promising for use with a real biological sample.

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.

Design of Functional Magnetic Nanocomposites for Bioseparation

Magnetic materials have been widely used in bioseparation in recent years due to their good biocompatibility, magnetic properties, and high binding capacity. In this review, we provide a brief introduction on the preparation and bioseparation applications of magnetic materials including the synthesis and surface modification of magnetic nanoparticles as well as the preparation and applications of magnetic nanocomposites in the separation of proteins, peptides, cells, exosomes and blood. The current limitations and remaining challenges in the fabrication process of magnetic materials for bioseparation will be also detailed.

Recent Applications of Molecularly Imprinted Sol-Gel Methodology in Sample Preparation

Due to their selectivity and chemical stability, molecularly imprinted polymers have attracted great interest in sample preparation. Imprinted polymers have been applied for the extraction and the enrichment of different sorts of trace analytes in biological and environmental samples before their analysis. Additionally, MIPs are utilized in various sample preparation techniques such as SPE, SPME, SBSE and MEPS. Nevertheless, molecularly imprinted polymers suffer from thermal (stable only up to 150 °C) and mechanical stability issues, improper porosity and poor capacity. The sol-gel methodology as a promising alternative to address these limitations allowing the production of sorbents with controlled porosity and higher surface area. Thus the combination of molecularly imprinted technology and sol-gel technology can create influential materials with high selectivity, high capacity and high thermal stability. This work aims to present an overview of molecularly imprinted sol-gel polymerization methods and their applications in analytical and bioanalytical fields.

Molecularly Imprinted Polymers for Gossypol via Sol⁻Gel, Bulk, and Surface Layer Imprinting-A Comparative Study

Three gossypol molecularly imprinted polymers (MIPs) were prepared by bulk polymerization (MIP1), surface layer imprinting using silica gel as the support (MIP2), and the sol-gel process (MIP3). The as-prepared MIPs were characterized by SEM and nitrogen adsorption-desorption techniques to study the morphology structure. The adsorption experiments exhibited that MIP1 had adsorption capacity as high as 564 mg·g-1. The MIP2 showed faster adsorption kinetics than MIP1 and MIP3. The adsorption equilibrium could be reached for gossypol in 40 min. A selectivity study showed that the adsorption capacity of MIPs for gossypol was about 1.9 times higher than that of the structurally-similar analogs ellagic acid and 6.6 times higher than that of the quercetin. It was found that the pseudo-second-order kinetic model and the Freundlich isotherm model were more applicable for the adsorption kinetics and adsorption isotherm of gossypol binding onto the MIP1 and MIP2, respectively. Results suggested that among those three, the MIP2 was a desirable sorbent for rapid adsorption and MIP1 was suitable for selective recognition of gossypol.

Magnetic boronate modified molecularly imprinted polymers on magnetite microspheres modified with porous TiO2 (Fe3O4@pTiO2@MIP) with enhanced adsorption capacity for glycoproteins and with wide operational pH range

Boronate-affinity based molecularly imprinted polymers (MIPs) are beset by the unsatisfied adsorption capacity and narrow working pH ranges. A magnetic molecularly imprinted polymer containing phenylboronic acid groups was placed on the surface of Fe₃O₄ (magnetite) microspheres coated with porous TiO₂ (Fe₃O₄@pTiO₂@MIP). In contrast to its silica analog (Fe₃O₄@SiO₂@MIP), the flowerlike Fe₃O₄@pTiO₂ offers more binding sites for templates. Thus, the adsorption capacity of the Fe₃O₄@pTiO₂@MIP is strongly enhanced. The strong electron-withdrawing effects of Ti(IV) enable the boronic acid of the MIP to have better affinity for glycoproteins at a wide pH range from 6.0 to 9.0. Consequently, the Fe₃O₄@pTiO₂@MIP exhibits higher adsorption for glycoproteins than Fe₃O₄@SiO₂@MIP in both basic and acidic medium. The Fe₃O₄@pTiO₂@MIPs were eluted with 5% acetic acid aqueous solution containing 30% acetonitrile, and the eluate was analyzed by MALDI-TOF MS. The method was applied to the selective extraction and quantitation of horseradish peroxidase (HRP) in spiked fetal bovine serum (FBS). The linear range is 0.40-10 μg·mL^-1 with the limit of detection of 0.31 μg·mL^-1. In our perception, this work has a wide scope in that is paves the way to a more widespread application of boronate affinity based MIPs for analysis of glycoproteins and related glyco compounds even at moderately acidic pH values. Graphical abstract Schematic presentation of the magnetic boronate modified molecularly imprinted polymer on magnetic spheres modified with porous TiO₂ (Fe₃O₄@pTiO₂@MIP). It was applied to extract glycoprotein in spiked both basic fetal bovine serum (FBS) and acidic urine samples prior to quantitation by MALDI-TOF mass spectrometry.

Magnetic protein imprinted polymers: a review

Protein imprinted polymers have received a lot of interest in the past few years because of their applications as tailor-made receptors for biomacromolecules. Generally, the preparation of these polymers requires numerous and time-consuming steps. But their coupling with magnetic nanoparticles simplifies and speeds up the synthesis of these materials. Some recent papers describe the use of protein imprinted polymer (PIP) coupled to magnetic iron oxide nanoparticles (MION) for the design of MION@PIP biosensors. With such systems, a target protein can be specifically and selectively captured from complex media due to exceptional chemical properties of the polymer. Despite such performances, only a limited number of studies address these hybrid nanosystems. This review focuses on the chemistry and preparation of MION@PIP nanocomposites as well as on the metrics used to characterize their performances.

A molecularly imprinted dual-emission carbon dot-quantum dot mesoporous hybrid for ratiometric determination of anti-inflammatory drug celecoxib

We report on a ratiometric fluorescent sensor based on dual-emission molecularly imprinted mesoporous silica embedded with carbon dots and CdTe quantum dots (mMIP@CDs/QDs) for celecoxib (CLX) as target molecule. The fluorescence of the embedded CDs is insensitive to the analyte while the green emissive QDs are selectively quenched by it. This effect is much stronger for the MIP than for the non-imprinted polymer, which indicates a good recognition ability of the mesoporous MIP. The hybrid sensor also exhibited good selectivity to CLX over other substances. The ratio of the intensity at two wavelengths (F₅₅₀/F₄₄₀) proportionally decreased with the increasing of CLX concentration in the range of 0.08-0.90μM. A detection limit as low as 57nM was achieved. Experimental results testified that this sensor was highly sensitive and selective for the detection of CLX in human serum samples.

Large-pore, silica particles with antibody-like, biorecognition sites for efficient protein separation

The MI-LPSPs, with antibody-like, bio-recognition sites, displayed good affinity and excellent binding selectivity to BSA.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Inhibitor-assisted synthesis of silica-core microbeads with pepsin-imprinted nanoshells

An innovative approach for imprinting proteins based on inhibitor-assisted templating of core–nanoshell microbeads is developed to address the challenges in protein purification.

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.

Water-compatible surface-imprinted microspheres for high adsorption and selective recognition of peptide drug from aqueous media

Through employing a synergetic effect of directional and non-directional interactions, surface-imprinted microspheres can selectively recognize thymopentin in aqueous media.

A porous hybrid imprinted membrane for selectively anchoring target proteins from a complex matrix

The proposed route for the polymerization of CP/CNT/DA-MIM (A) and the recognition protocol of CP/CNT/DA-MIM (B).

Effect of annealing temperature on the structure of carbon encapsulated Fe3O4 nanospheres

Yolk–shell structured Fe₃O₄@C was obtained at 600 °C. A possible evolution mechanism of core–shell to yolk–shell Fe₃O₄@C is elaborated.

Combination of surface imprinting and immobilized template techniques for preparation of core-shell molecularly imprinted polymers based on directly amino-modified Fe3O4 nanoparticles for specific recognition of bovine hemoglobin

In this work, the core-shell bovine hemoglobin (BHb)-imprinted superparamagnetic nanoparticles (Fe₃O₄@BHb-MIPs) were synthesized by combining for the first time a surface imprinting technique and a two-step immobilized template strategy. Initially, amino-functionalized Fe₃O₄ nanoparticles (Fe₃O₄@NH₂) were synthesized directly through a facile one-pot hydrothermal method. Next, BHb was immobilized on the surface of Fe₃O₄@NH₂ through non-covalent interactions. Then, siloxane co-polymerization on the Fe₃O₄@NH₂-protein complex surface resulted in a polymeric network molded around BHb which then became further immobilized. Finally, a thin polymer layer with specific recognition cavities for BHb was formed on the surface of Fe₃O₄@NH₂ after the removal of the template protein. The morphology and structure property of the prepared magnetic nanoparticles were characterized by transmission electronic microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), and vibrating sample magnetometer (VSM). To obtain the best selectivity and binding performance, the polymerization and adsorption conditions were investigated in detail. Under the optimized conditions, the Fe₃O₄@BHb-MIPs exhibited fast adsorption kinetics, large binding capacity, significant selectivity, and favorable reproducibility. The resultant Fe₃O₄@BHb-MIPs could not only specifically extract BHb from a mixed standard protein mixture, but also selectively enriched BHb from a real bovine blood sample. In addition, the synthetic process was quite simple and the stability and regeneration of the Fe₃O₄@BHb-MIPs were also satisfactory.

Self-assembled supramolecular structure of N,N,N′,N′-tetramethylethylenediammonium-bis-(4-nitrophenolate): synthesis, single crystal growth and photo physical properties

The synthesis, growth and structure of a novel organic third order nonlinear optical (NLO) crystal namely, N,N,N′,N′-tetramethylethylenediammonium-bis(4-nitrophenolate) (TMEDA4NP) is presented.

Specific removal of protein using protein imprinted polydopamine shells on modified amino-functionalized magnetic nanoparticles

A simple approach for the specific removal of protein using polydopamine imprinted shells on modified amino-functionalized magnetic nanoparticles was developed.

Facile in situ growth of Fe3O4 nanoparticles on hydroxyapatite nanorods for pH dependent adsorption and controlled release of proteins

The magnetic hydroxyapatite nanostructures were prepared by hydrothermal technique and studied their protein adsorption and in vitro cytotoxicity in humen MGC-803 cell.