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.

Preparation and Application of Magnetic Molecularly Imprinted Plasmonic SERS Composite Nanoparticles

Magnetic molecularly imprinted polymers (MMIPs) are used as artificial antibody materials. MMIPs have attracted a great deal of interest because of their low cost, wide practicality, predetermination, stability and their ability to achieve rapid separation from complex sample environments by the action of external magnetic field. MMIPs can simulate the natural recognition of entities. They are widely used because of their great advantages in terms of high selectivity. In this review article, the preparation methods of Fe3O4 NPs and a detailed summary of the commonly used methods for amination modification of Fe3O4 NPs are introduced, preparation of Ag NPs of different sizes and Au NPs of various shapes and preparation methods of magnetic molecularly imprinted plasmonic SERS composite nanoparticles such as Fe3O4@Ag NPs, Fe3O4/Ag NPs, Fe3O4@Au NPs, Fe3O4/Au NPs, Fe3O4@Au/Ag NPs and Fe3O4@Ag@Au NPs are main summarized. In addition, preparation process and the current application of MMIPs prepared from magnetic molecularly imprinted plasmonic SERS composite nanoparticles incorporating different functional monomers in a nuclear-satellite structure are also presented. Finally, the existing challenges and future prospects of MMIPs in applications are discussed.

Molecularly imprinted polymers for selective extraction/microextraction of cancer biomarkers: A review

Over recent years, great efforts have been extensively documented in top scientific journals on the development of methods for early diagnosis, treatment, and monitoring of cancers which are prevalent critical diseases with a high mortality rate among men and women. The determination of cancer biomarkers using different optimum methodologies is one of the finest options for achieving these goals with more precision, speed, and at a lower cost than traditional clinical procedures. In this regard, while focusing on specific biomarkers, molecularly imprinted technology has enabled novel diagnostic techniques for a variety of diseases. Due to the well-known advantages of molecularly imprinted polymers (MIPs), this review focuses on the current trends of MIPs-based extraction/microextraction methods, specifically targeting cancer biomarkers from various matrices. These optimized methods have demonstrated high selectivity, accuracy, sorbent reusability, extraction recovery, and low limits of detection and quantification for a variety of cancer biomarkers, which are a powerful tool to provide early diagnosis, prognosis, and treatment monitoring, with potential clinical application expected soon. This review highlights the key progress, specific modifications, and strategies used for MIP synthesis. The future perspectives for cancer biomarkers purification and determination by fabricating MIP-based techniques are also discussed.

The molecular imprinting of magnetic nanoparticles with boric acid affinity for the selective recognition and isolation of glycoproteins

A strategy was designed for the molecular imprinting of magnetic nanoparticles with boric acid affinity (MNPs@MIP) which were then used for the selective recognition and isolation of glycoproteins. Fe₃O₄ nanoparticles were prepared by a solvothermal method and direct silanization by the condensation polymerization of aminopropyltriethoxysilane (APTES). Subsequently, phenylboric acid was functionalized by reductive amination between 2,3-difluoro-4-formyl phenylboric acid (DFFPBA) and the amido group. The resultant Fe₃O₄@SiO₂–DFFPBA was then used for the selective adsorption of a glycoprotein template. Finally, a molecularly imprinted layer was covered on the surface nanoparticles by the condensation polymerization of tetraethyl orthosilicate (TEOS). The adsorption capacities of the resultant MNPs@MIP–HRP and MNPs@MIP–OVA to horseradish peroxidase (HRP) or ovalbumin (OVA) were significantly higher than non-imprinted particles (MNPs@NIP). Moreover, the adsorption capacities of MNPs@MIP–HRP and MNPs@MIP–OVA on non-template protein and non-glycoprotein bovine serum albumin (BSA) were significantly lower than those of their respective template proteins, thus indicating that both of the prepared MNPs@MIP exhibited excellent selectivity.

A strategy was designed for the preparation of molecular imprinting of magnetic nanoparticles with boric acid affinity (MNPs@MIP), and the resultant MNPs@MIP exhibited excellent selectivity for template glycoproteins.

Biomass activated carbon-derived imprinted polymer with multi-boronic acid sites for selective capture of glycoprotein

Glycoproteins play crucial roles in many biological events such as protein folding, information transmission, nerve conduction, and molecular recognition. Some glycoproteins serve as disease biomarkers in clinical settings. However, selective detection of glycoprotein often faces great challenges, owing to its low abundance in complex biological samples. In this case, develop a highly sensitive and selective approach for glycoprotein detection is urgently needed. Molecularly imprinted polymers (MIPs) have proved to be an ideal absorbent material in detection and separation science. Herein, a novel biomass activated carbon-derived imprinted polymer (BAC@PEI/PBA/MIPs) was fabricated for selective recognition of glycoprotein. The as-prepared BAC@PEI/PBA/MIPs was synthesized using waste tea derived carbon as matrix, albumin chicken egg (OVA) as template, and dopamine as functional monomer. Branched polyethyleneimine (PEI) was covalently bonded on the BAC surface to increase the number of boronic acid moieties. Benefiting from the self-polymerization of dopamine and multi-boronic acid sites, a great number of recognition sites were presented under mild conditions. The static adsorption experiment showed that the BAC@PEI/PBA/MIPs exhibited a high binding capacity of 196.2 mg/g, rapid adsorption dynamics of 40 min, excellent selectivity and satisfactory reusability for OVA. Furthermore, the practicability of BAC@PEI/PBA/MIPs was verified by isolation of OVA from egg white. The good binding performance and facile preparation process make BAC@PEI/PBA/MIPs attractive for glycoprotein recognition, indicating its potential applications in biomedical research and clinical diagnostics.

Magnetic Polydopamine Modified with Choline-Based Deep Eutectic Solvent for the Magnetic Solid-Phase Extraction of Sulfonylurea Herbicides in Water Samples

A novel magnetic solid-phase extraction technique coupled to ultraperformance liquid chromatography has been developed for separation and preconcentration of four sulfonylurea herbicides (sulfosulfuron, bensulfuron-methyl, pyrazosulfuron-ethyl and halosulfuro-methyl) in aqueous samples. The key point of this method was the application of a novel magnetic nanomaterial that composed of a low eutectic solvent as a shell coated on the magnetic core modified by polydopamine. The extensive active sites outside the low eutectic solvent can effectively adsorb the target herbicide in the extraction process. The obtained magnetic adsorbent was characterized with fourier transform infrared spectrometry, scanning electron microscopy and vibrating sample magnetometer. The influence parameters relevant to this method were optimized. Under the optimum conditions, good linearities could be obtained within the range of 1.0-200 μg L-1 for all analytes, with correlation coefficients ≥0.9908. The limit of detections of the method was between 0.0074 and 0.0100 μg L-1 and the relative standard deviations were 1.1-3.6%. The enrichment factor is 66.6. In the final experiment, the proposed method was successfully applied to the analysis of sulfonylurea herbicides residue in environment and drinking-water samples, and the obtained recoveries were between 70.6% and 109.4%.

Effect of surface functionality of molecularly imprinted composite nanospheres on specific recognition of proteins

The surface functionality of biomaterial plays a primary role in determining its application in biorecognition and drug delivery. In our work, three types of synthetic tailoring polymer nanospheres with hierarchical architecture were constructed to obtain functional polymer layer with disparate chemical motifs for protein adsorption via surface imprinting and grafting copolymerization. In this polymerization system, the structure stability of template protein bovine serum albumin (BSA) is well maintained within a certain range, which facilitated the accurate imprinting and precise identification. A comprehensive protocol for screening different functional layer is proposed through comparing the adsorption behavior, selectivity, identification and responsiveness to medium pH of three functional layers. Our study demonstrates that surface functionality greatly influences the adsorption capacity and selectivity of adsorption material. The functional layer with ionic liquid structure that could only provide multiple non-covalent binding sites is beneficial to the proteins aggregation and extraction, while the anti-nonspecific binding functional layer of biomaterial with zwitterionic structure for specific protein capture is promising to serve as a preferable antigen-antibody communication network, which shows great potential for protein recognition and separation. In summary, our proposed strategy provides a systematic selection criterion of biomaterials for effective application in biosensors.

Determination of Aflatoxin B1 and B2 in Vegetable Oils Using Fe3O4/rGO Magnetic Solid Phase Extraction Coupled with High-Performance Liquid Chromatography Fluorescence with Post-Column Photochemical Derivatization

In this study, magnetic graphene nanocomposite Fe3O4/rGO was synthesized by facile one-pot solvothermal method. The nanocomposite was successfully used as magnetic solid phase extraction (MSPE) adsorbents for the determination of aflatoxins in edible vegetable oils through the π-π stacking interactions. MSPE parameters including the amount of adsorbents, extraction and desorption time, washing conditions, and the type and volume of desorption solvent were optimized. Under optimal conditions, good linear relationships were achieved. Limits of detection of this method were as low as 0.02 µg/kg and 0.01 µg/kg for aflatoxin B1 and B2, respectively. Finally, the magnetic graphene nanocomposite was successfully applied to aflatoxin analysis in vegetable oils. The results indicated that the recoveries of the B-group aflatoxins ranged from 80.4% to 106.0%, whereas the relative standard deviations (RSDs) were less than 8.1%. Owing to the simplicity, rapidity and efficiency, Fe3O4/rGO magnetic solid phase extraction coupled with high-performance liquid chromatography fluorescence with post-column photochemical derivatization (Fe3O4/rGO MSPE-HPLC-PCD-FLD) is a promising analytical method for routine and accurate determination of aflatoxins in lipid matrices.

A fluorescent molecularly imprinted device for the on-line analysis of AFP in human serum

MIT is a promising strategy in antibody free analysis for tumour markers. Conventional nanosized MIPs with off-line analysis are beset by tedious operation and unsatisfactory analysis performance. In this work, an on-line analytical device to directly detect AFP, which is a typical tumour marker in cancer screening, was prepared for the first time. A microscope slide was chosen to be the basis of the device. APBA-PA, a polymerizable fluorescent boronic acid monomer, was synthesised and grafted on the surface of the microscope slide to act as the signal transduction pathway between the templates and the device. Along with the hydrolysis of TEOS and the elution of the templates, a portable, stable, easy to operate and low-cost analysis device for AFP with excellent repeatability was successfully prepared. Owing to the excellent selectivity and highly sensitive fluorescence response ability of the device towards the templates, the on-line detection of AFP in human serum was realized. A series of characterizations were applied to the device, and its analysis performance and possible detection mechanism were carefully studied. Furthermore, the device exhibited appropriate application prospects by comparing its analysis results with those of the commercially available ELISA. In our perception, this work is an important step towards MIPs for clinical applications.

Determination of sialic acid in serum samples by dispersive solid-phase extraction based on boronate-affinity magnetic hollow molecularly imprinted polymer sorbent

Boronate-affinity magnetic hollow molecularly imprinted polymers (B-MhMIPs) were prepared with sialic acid (SA) as the template, 3-aminophenylboronic acid (APBA) as the functional monomer and glycidilmethacrylate (GMA) as the co-monomer to chemisorb Fe3O4 nanoparticles. Furthermore, the hollow structure made the nanoparticles have more binding sites at both internal and external surfaces, which can facilitate the removal of template molecules from polymers and enhance the adsorption abilities towards SA. After optimizing, the adsorption pH was controlled at 4.0, and this was different from most cis-diol-containing compounds. Under the optimal conditions, the limit of detection for SA was 0.025 μg mL-1 (n = 3). This method was applied to analyze serum samples with different spiked levels, and the recoveries of the SA were in the range of 70.9-106.2%. These results confirmed the superiority of the B-MhMIPs for selective and efficient enrichment of trace SA from complex matrices.

Synthesis of magnetic molecularly imprinted nanoparticles with multiple recognition sites for the simultaneous and selective capture of two glycoproteins

Magnetic molecularly imprinted nanoparticles with multiple recognition sites were prepared, which exhibited excellent selectivity for two glycoproteins simultaneously.

Boronate-affinity hollow molecularly imprinted polymers for the selective extraction of nucleosides

Preparation of a boronate-affinity hollow molecularly imprinted polymer and its application as an SPE adsorbent for the selective enrichment of nucleosides.

Anchoring β-cyclodextrin modified lysine to polymer monolith with biotin: specific capture of plasminogen

A biotin-Lys-CD based monolithic material was employed for the specific capture of plasminogen.