The preparation of bovine serum albumin surface-imprinted superparamagnetic polymer with the assistance of basic functional monomer and its application for protein separation

Recent Advances in Molecular Imprinting for Proteins on Magnetic Microspheres

The separation of proteins in biological samples plays an essential role in the development of disease detection, drug discovery, and biological analysis. Protein imprinted polymers (PIPs) serve as a tool to capture target proteins specifically and selectively from complex media for separation purposes. Whereas conventional molecularly imprinted polymer is time-consuming in terms of incubation studies and solvent removal, magnetic particles are introduced using their magnetic properties for sedimentation and separation, resulting in saving extraction and centrifugation steps. Magnetic protein imprinted polymers (MPIPs), which combine molecularly imprinting materials with magnetic properties, have emerged as a new area of research hotspot. This review provides an overview of MPIPs for proteins, including synthesis, preparation strategies, and applications. Moreover, it also looks forward to the future directions for research in this emerging field.

Functional Nanoparticles with Magnetic 3D Covalent Organic Framework for the Specific Recognition and Separation of Bovine Serum Albumin

Glutathione functionalized magnetic 3D covalent organic frameworks combined with molecularly imprinted polymer (magnetic 3D COF–GSH MIPs) were developed for the selective recognition and separation of bovine serum albumin (BSA). Ultrasonication was used to prepare magnetic 3D COFs with high porosity (~1 nm) and a large surface area (373 m² g⁻¹). The magnetic 3D COF–GSH MIP nanoparticles had an imprinting factor of 4.79, absorption capacity of 429 mg g⁻¹, magnetic susceptibility of 32 emu g⁻¹, and five adsorption–desorption cycles of stability. The proposed method has the advantages of a shorter equilibrium absorption time (1.5 h), higher magnetic susceptibility (32 emu g⁻¹), and larger imprinting factor (4.79) compared with those reported from other studies. The magnetic 3D COF–GSH MIPs used with BSA had selectivity factors of 3.68, 2.76, and 3.30 for lysozyme, ovalbumin, and cytochrome C, respectively. The successful recognition and separation of BSA in a real sample analysis verified the capability of the magnetic 3D COF–GSH MIP nanoparticles.

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.

Preparation of IgG imprinted polymers by metal-free visible-light-induced ATRP and its application in biosensor

Immunoglobulin G (IgG) is related to the occurrence of many diseases, such as measles and inflammatory. In this paper, IgG imprinted polymers (IgGIPs) were fabricated on the surface of nano Au/nano Ni modified Au electrode (IgGIPs/AuNCs/NiNCs/Au) via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP). The IgGIPs were prepared by IgG conjugated with fluorescein isothiocyanate (FITC-IgG) as both a template and a photocatalyst. After the templates were removed, the photocatalysts (FITC) would not remain in the polymer and avoided all the effect of catalysts on the electrode. The fabricated electrodes were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Under the optimized conditions, IgGIPs/AuNCs/NiNCs/Au was prepared and used as an electrochemical biosensor. The biosensor could be successfully applied for the determination of IgG by differential pulse voltammetry (DPV) measurement. The results showed that the proposed biosensor displayed a broader linear range and a lower detection limit for IgG determination when it was compared to those similar IgG sensors. The linear range from 1.0 × 10^-6 mg L^-1 to 1.0 × 10¹ mg L^-1 was obtained with a low detection limit (LOD) of 2.0 × 10^-8 mg L^-1 (S/N = 3). Briefly, the biosensor in this study introduced an easy and non-toxic method for IgG determination and also provided a progressive approach for designing protein imprinted polymers.

Preparation of monodisperse, restricted-access, media-molecularly imprinted polymers using bi-functional monomers for solid-phase extraction of sarafloxacin from complex samples

Monodisperse restricted-access media bi-functional monomers with molecularly imprinted polymers (RAM-MIPs) were constructed using surface-initiated atom transfer radical polymerization. They were used as solid-phase extraction (SPE) adsorbents to enrich sarafloxacin (SAR) residues from egg samples, and influences on their performance were investigated. Optimum synthesis of RAM-MIPs was achieved by combining a bi-functional monomer (4-vinylpyridine-co-methacrylic acid, 1:3) with an 8:1:32:8 ratio of a template molecule, cross-linker, and restricted-access functional monomer. The SAR imprinting factor of RAM-MIPs was 6.05 and the selectivity coefficient between SAR and other fluoroquinolones was 1.86-2.64. Compared with traditional MIPs, the RAM-MIPs showed better SAR enrichment and selectivity during extraction of a complex protein-containing solution. Empty SPE cartridges were filled with RAM-MIP microspheres as SPE adsorbents. The limit of quantitation for SAR was 4.23 ng g^-1 (signal-to-noise ratio = 10) and the mean SAR recovery from spiked egg samples was 94.0-101.3%. Intra-day and inter-day relative standard deviations were 1.1-9% and 1.5-3.3%, respectively.

Development of surface imprinted heterogeneous nitrogen-doped magnetic carbon nanotubes as promising materials for protein separation and purification

To promote the development of molecular imprinting technique in the separation and analysis of protein, novel bovine serum albumin (BSA) surface imprinted nitrogen-doped magnetic carbon nanotubes (N-MCNTs@MIPs) are developed by this paper. The imprinted materials are prepared by depositing polydopamine (PDA) on the surface of nitrogen-doped magnetic carbon nanotubes (N-MCNTs). N-MCNTs prepared by high temperature pyrolysis and chemical vapor deposition exhibit high specific surface area, positive hydrophilicity, abundant nitrogen functional groups and excellent magnetic properties. These characteristics are conducive to the increase of effective binding sites, the smooth development of the protein imprinting process in the aqueous phase, the improvement of the binding capacity and the simplification of the separation process. The amount of BSA adsorbing on the N-MCNTs@MIPs can reach 150.86 mg/g within 90 min. The imprinting factor (IF) is 1.43. The results of competitive adsorption and separation of fetal bovine serum showed that N-MCNTs@MIPs can specifically recognize BSA. The excellent reusability and separation ability for real sample prove that N-MCNTs@MIPs have the potential to be applied to the separation and purification of proteins in complex biological samples.

PEGylated Thermo-Sensitive Bionic Magnetic Core-Shell Structure Molecularly Imprinted Polymers Based on Halloysite Nanotubes for Specific Adsorption and Separation of Bovine Serum Albumin

Novel PEGylated thermo-sensitive bionic magnetic core-shell structure molecularly imprinted polymers (PMMIPs) for the specific adsorption and separation of bovine serum albumin (BSA) were obtained via a surface-imprinting technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), and specific surface area (BET), were adopted to demonstrate that novel PMMIPs were successfully synthesized. Subsequently, the prepared PMMIPs were used as the extractor for BSA and were combined with magnetic solid-phase extraction. The concentrations of BSA were detected by UV-vis spectrophotometry at 278 nm. The maximum adsorption capacity of the PMMIPs was 258 mg g⁻¹, which is much higher than that of non-imprinted polymer (PMNIPs). PMMIPs showed favorable selectivity for BSA against reference proteins, i.e., bovine hemoglobin, ovalbumin and lysozyme. PMMIPs were further used to recognize BSA in protein mixtures, milk, urine and sewage, these results revealed that approximately 96% of the ideal-state adsorption capacity of PMMIPs for BSA was achieved under complicated conditions. Regeneration and reusability studies demonstrated that adsorption capacity loss of the PMMIPs was not obvious after recycling for four times. Facile synthesis, excellent adsorption property and efficient selectivity for BSA trapping are features that highlight PMMIPs as an attractive candidate for biomacromolecular purification.

Advances in the development of molecularly imprinted polymers for the separation and analysis of proteins with liquid chromatography

This review documents recent advances in the design, synthesis, characterization, and application of molecularly imprinted polymers in the form of monoliths and particles/beads for the use in the separation and analysis of proteins with solid-phase extraction or liquid chromatography. The merits of three-dimensional molecular imprinting, whereby the molecular template is randomly embedded in the polymer, and two-dimensional imprinting, in which the template is confined to the surface, are described. Target protein binding can be achieved by either using the entire protein as a template or by using a protein substructure as template, that is, a peptide, as in the "epitope" approach. The intended approach and strategy then determine the choice of polymerization method. A synopsis has been provided on methods used for the physical, chemical, and functional characterizations and associated performance evaluations of molecularly imprinted and nonimprinted control polymers, involving a diverse range of analytical techniques commonly used for low and high molecular mass analytes. Examples of recent applications demonstrate that, due to the versatility of imprinting methods, molecularly imprinted monoliths or particles/beads can be adapted to protein extraction/depletion and separation procedures relevant to, for example, protein biomarker detection and quantification in biomedical diagnostics and targeted proteomics.

Synthesis and characterization of albumin imprinted polymeric hydrogel membranes for proteomic studies

In this presented study, a novel molecularly imprinted polymeric hydrogel membranes (PHMs) were developed to use for the albumin depletion studies. For this, albumin imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-phenylalanine methyl ester) polymeric hydrogel membranes [p(HEMA-MAP) PHMs] were synthesized by the photopolymerization technique, and then characterized by SEM, EDX, FT-IR and swelling studies. Synthesized PHMs had spherical structure and the MAP monomer incorporation onto the PHMs was determined by EDX analysis by using nitrogen stoichiometry. Also, the swelling ratio of the albumin imprinted p(HEMA-MAP) PHMs was determined as 215%. The optimum albumin adsorption condition (adsorption capacity, medium pH, adsorption rate, temperature, ionic strength) were studied and the maximum albumin adsorption capacity was found to be as 34.28 mg/g PHMs. Selectivity experiments were also carried out with the presence of the competitive proteins such as lysozyme and amylase, and the results demonstrated that the albumin imprinted p(HEMA-MAP) PHMs showed high affinity towards the BSA molecules than the competitive proteins of lysozyme and amylase. Adsorbed albumin was desorbed from the PHMs by 1.0 M of NaCl, and the reusability of the imprinted PHMs was also demonstrated for five successive adsorption-desorption cycles without any significant loss in the albumin adsorption capacity. As an application, sodium-dodecyl sulfate polyacrylamide gel electrophoresis was used to indicate the albumin depletion efficiency of albumin imprinted p(HEMA-MAP) PHMs. This presented study showed that, these imprinted membranes are promising for proteomic studies and applications, and can be used for the investigations for human diagnostics.

Nanosized aptameric cavities imprinted on the surface of magnetic nanoparticles for high-throughput protein recognition

The authors introduce a new kind of surface artificial biomimetic receptor, referred to as aptameric imprinted polymer (AIP), for separation of biological macromolecules. Highly dispersed magnetic nanoparticles (MNPs) were coated with silica and then functionalized with methacrylate groups via silane chemistry. The aptamer was covalently immobilized on the surface of nanoparticles via a "thiol-ene" click reaction. Once the target analyte (bovine serum albumin; BSA) has bound to the aptamer, a polymer is created by 2-dimensional copolymerization of short-length poly(ethylene glycol) and (3-aminopropyl)triethoxysilane. Following removal of BSA from the polymer, the AIP-MNPs presented here can selectively capture BSA with a specific absorbance (κ) as high as 65. When using this AIP, the recovery of BSA from spiked real biological samples is >97%, and the adsorption capacity is as high as 146 mg g^-1. In our perception, this method has a wide scope in that it may be applied to the specific extraction of numerous other biomolecules. Graphical abstract Schematic presentation of the AIP (aptamer-imprinted polymer) introduced here. The surface of silica coated magnetic nanoparticles is modified with a polymer that is covalently modified with an aptamer against bovine serum albumin (BSA).

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 multi-walled carbon nanotube-based magnetic molecularly imprinted polymer as a highly selective sorbent for ultrasonic-assisted dispersive solid-phase microextraction of sotalol in biological fluids

A modified multiwalled carbon nanotube-based magnetic molecularly imprinted polymer (MWCNT-MMIP) was synthesized and applied for selective extraction and preconcentration of sotalol (SOT) in biological fluid samples by using ultrasonic-assisted dispersive solid-phase microextraction (UA-DSPME).

Self-cleaned electrochemical protein imprinting biosensor basing on a thermo-responsive memory hydrogel

Herein, the self-cleaned electrochemical protein imprinting biosensor basing on a thermo-responsive memory hydrogel was constructed on a glassy carbon electrode (GCE) with a free radical polymerization method. Combining the advantages of thermo-responsive molecular imprinted polymers and electrochemistry, the resulted biosensor presents a novel self-cleaned ability for bovine serum albumin (BSA) in aqueous media. As a temperature controlled gate, the hydrogel film undergoes the adsorption and desorption of BSA basing on a reversible structure change with the external temperature stimuli. In particular, these processes have been revealed by the response of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of electroactive [Fe(CN)₆]^3-/4-. The results have been supported by the evidences of scanning electron microscopy (SEM) and contact angles measurements. Under the optimal conditions, a wide detection range from 0.02μmolL^-1 to 10μmolL^-1 with a detection limit of 0.012 μmolL^-1 (S/N = 3) was obtained for BSA. This proposed BSA sensor also possesses high selectivity, excellent stability, acceptable recovery and good reproducibility in its practical applications.

Selective extraction of proteins and other macromolecules from biological samples using molecular imprinted polymers

The accurate determination of intact macromolecules in biological samples, such as blood, plasma, serum, urine, tissue and feces is a challenging problem. The increased interest in macromolecules both as candidate drugs and as biomarkers for diagnostic purposes means that new method development approaches are needed. This review charts developments in the use of molecularly imprinted polymers first for small-molecular-mass compounds then for proteins and other macromolecules. Examples of the development of molecularly imprinted polymers for macromolecules are highlighted. The two main application areas to date are sensors and separation science, particularly SPE. Examples include peptides and polypeptides, lysozyme, hemoglobin, ovalbumin, bovine serum albumin and viruses.

Computer-aided design and synthesis of magnetic molecularly imprinted polymers with high selectivity for the removal of phenol from water

A molecular simulation method was introduced to compute the phenol-monomer pre-assembled system of a molecularly imprinted polymer. The interaction type and intensity between phenol and monomer were evaluated by combining binding energy and charge transfer with complex conformation. The simulation results indicate that interaction energies are simultaneously affected by the type of monomer and the ratio between phenol and monomers. At the same time, we considered that by increasing the amount of functional monomer is not always better for preparing molecularly imprinter polymers. In this study, three kinds of novel magnetic phenol-imprinted polymers with favorable specific adsorption effects were prepared by the surface imprinting technique combined with atom transfer radical polymerization. Various measures were selected to characterize the structure and morphology to obtain the optimal polymer. The characterization results show that the optimal polymer has suitable features for further adsorption process. A series of static adsorption experiments were conducted to analyze its adsorption performance, which follows the Elovich model from the kinetic analysis and the Sips equation from the isothermal analysis. To further verify the reliability and accuracy of the simulation results, the effects of different monomers on the adsorption selectivity were also determined. They display higher selectivity towards phenol than 4-nitrophenol.The results from the simulation of the pre-assembled complexes are in reasonable agreement with those from the experiment.

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.

Molecularly imprinted hollow sphere array for the sensing of proteins

Mono-dispersed molecularly imprinted hollow spheres (MIHSs) for hemoglobin (Hb) were prepared by employing silica nanospheres as the sacrificial templates. The obtained hollow spheres with uniform particle size of 360 nm in diameter were characterized by transmission electron microscopy. The outstanding affinities of these MIHSs to the target protein were confirmed by adsorption experiment in aqueous solution. Adsorption equilibrium was achieved within 10 min while the binding capacity (Qmax ) of Hb was 8.84 µmol g(-1) at pH7.0. Furthermore, the MIHSs were successfully assembled into a closely-packed 3D colloidal array. The molecularly imprinted hollow sphere array (MIHSA) can selectively recognize Hb. As the concentration of Hb increased, the structure color of the MIHSA changed from blue to green, and turn to white finally with maximum red shift for 43 nm. The MIHSA showed promising potential for the naked-eye detection of target Hb. Reflection spectra of the MIHSA in response to different Hb concentrations (0.075-15 µmol L(-1) ).

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.

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.

Determination of protein binding affinities within hydrogel-based molecularly imprinted polymers (HydroMIPs)

Selective synthetic MIP recognition of a range of bio-significant proteins. Comparison of functional acrylamide-based polymer hydrogels as MIPs. MIP–protein dissociation constants within the micro-molar range. AFM measurements exhibited specific MIP interactions with cognate protein.