Chunbao Du

The effectively specific recognition of bovine serum albumin imprinted silica nanoparticles by utilizing a macromolecularly functional monomer to stabilize and imprint template

Structural stability of the template is one of the most important considerations during the preparation of protein imprinting technology. To address this limitation, we propose a novel and versatile strategy of utilizing macromolecularly functional monomers to imprint biomacromolecules. Results from circular dichroism and synchronous fluorescence experiments reflect the macromolecularly functional monomers tendency to interact with the protein surface instead of permeating it and destroying the hydrogen bonds that maintain the proteins structural stability, therefore stabilizing the template protein structure during the preparation of imprinted polymers. The imprinted polymers composed of macromolecularly functional monomers or their equivalent micromolecularly functional monomers over silica nanoparticles were characterized and carried out in batch rebinding test and competitive adsorption experiments. In batch rebinding test, the imprinted particles prepared with macromolecularly functional monomers exhibited an imprinting factor of 5.8 compared to those prepared by micromolecularly functional monomers with the imprinting factor of 3.4. The selective and competitive adsorption experiments also demonstrated the imprinted particles made by macromolecularly functional monomers possessed much better selectivity and specific recognition ability for template protein. Therefore, using macromolecularly functional monomers to imprint may overcome the mutability of biomacromolecule typically observed during the preparation of imprinted polymers, and thus promote the further development of imprinting technology.

Preparation of surface-imprinted microspheres effectively controlled by orientated template immobilization using highly cross-linked raspberry-like microspheres for the selective recognition of an immunostimulating peptide

Surface-imprinted microspheres were controllably synthesized using ionic liquid-functionalized microspheres with a highly cross-linked raspberry-like structure as the matrix via surface molecular self-assembly and precipitation polymerization in aqueous media at room temperature. An immunostimulating hexapeptide from human (IHH) with medical properties was chosen as a template molecule in the preparation of different molecularly imprinted microspheres (MIMs). The experiment process was tracked and the as-prepared microspheres were well characterized. Results reveal that the adsorption capacity and selective recognition of MIMs have a direct relationship with the properties of the functional chain of the ionic liquid-functionalized microspheres. Moreover, MIMs that have both high adsorption capacity and good selective recognition were used in competitive rebinding tests and analysis of urine samples, which demonstrated their potential use for IHH enrichment and in real samples.

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

Novel water-compatible ionic liquid-functionalized microspheres with molecularly imprinted shell layer were controllably synthesized via precipitation polymerization and surface imprinting technique. Here, a room-temperature ionic liquid was synthesized to prepare these surface-imprinted microspheres with excellent water solubility and multiple binding sites with template molecules. The peptide drug thymopentin (TP5) was chosen as a template molecule, which is known as an immunomodulating agent. The as-prepared microspheres were fully characterized. Results reveal that ionic liquid incorporation significantly improves the adsorption of TP5. Moreover, the adsorption property and recognition capability towards TP5 are closely related to the synergetic effect of electrostatic interaction and hydrogen bonding. Through employing the synergetic effect of directional and non-directional interactions, the surface-imprinted microspheres exhibit high adsorption capacity, good selective recognition, and rapid binding ability for TP5. The surface-imprinted microspheres demonstrate potential usage for TP5 enrichment from other biomolecules, and the proposed method was successfully applied for TP5 determination in thymopentin injection and urine.

Preparation of molecularly imprinted polymers using ion-pair dummy template imprinting and polymerizable ionic liquids

Ionic liquid based molecularly imprinted polymers have attracted considerable attention as biomimetic recognition materials due to their water-compatibility and high binding capacities. However, the selective recognition was unsatisfactory. In order to overcome this defect, we developed a novel dummy template ionic liquid based molecularly imprinted polymer, which used 1-butyl-3-vinylimidazolium α-aminohydrocinnamic acid salt as a functional monomer and the dummy template. Binding experiments showed that the obtained molecularly imprinted polymer possesses a high binding capacity (280.18 μmol g−1), imprinting factor (3.17) and selectivity factor (5.75). Molecular simulation results demonstrated that the high selectivity is attributed to the formation of ion-pairs between imidazolium and L-phenylalanine, which could be located in the imprinted cavities to improve the imprinted material’s efficiency. Subsequently, the dummy template ionic liquid based imprinted polymer was employed as packing in a solid phase extraction cartridge to analyze the L-phenylalanine in the blood of a phenylketonuria patient. The results indicated that the obtained dummy template ionic liquid based imprinted polymer has good analytical performance. Thus, the dummy imprinting combined with the ionic liquid is a useful way to improve the specific recognition of ionic liquid based molecular imprinted polymers, so that this method offers promising new applications in the field of the analysis of biological samples.

Preparation of surface-imprinted microspheres using ionic liquids as novel cross-linker for recognizing an immunostimulating peptide

Abstract Recently, the design and preparation of novel functional materials using biomimetic approaches for the high adsorption and precise selective capture of biomolecules have been actively investigated. In this work, molecularly imprinted microspheres (MIMs) with a homogeneous polymer shell anchored onto SiO2 core particles were successfully synthesized via the surface iniferter-initiated polymerization under room temperature in aqueous media. Herein, a clinically relevant immunostimulating hexapeptide from human casein (IHHC) was chosen as a template. Moreover, a novel double imidazolium dicationic ionic liquid with multiple binding sites was synthesized and used as the cross-linker to improve the recognition performance and enhance the adsorption capacity of MIMs simultaneously. The as-prepared microspheres were characterized through various methods. Results revealed that MIMs not only exhibited excellent selective recognition for IHHC but also possessed a high adsorption capacity through the synergistic effect of directional and non-directional interactions, which demonstrated their potential use in the practical application.

Synthesis of core–shell imprinting polymers with uniform thin imprinting layer via iniferter-induced radical polymerization for the selective recognition of thymopentin in aqueous solution

An approach for synthesizing core–shell imprinting polymers using P(EGDMA-CMS) microspheres prepared via dispersion polymerization as a core and employing a surface imprinting technique and iniferter-induced radical polymerization is described. N,N-Diethyldithiocarbamyl groups were immobilized on the surface of the supporting microspheres to form the surface iniferter and further prepare the imprinting layer. Thymopentin (TP5) was selected as the template molecule, which was known to be an immunomodulating agent that had medical properties. Here, a bifunctional ionic liquid (IL), namely, 1-vinyl-3-carbamoylmethyl-imidazolium chloride ([VACMIM]Cl), was synthesized and employed as a novel functional monomer on the basis of the demands of peptide imprinting and the designability of ILs. Under irradiation by UV light, the surface iniferter decomposed and then polymerization was initiated to form a thin surface imprinting layer with specific recognition cavities for TP5. The surface imprinting layer possessed a uniform thickness of ∼35 nm, which was beneficial for the mass transfer of the template TP5, owing to good control of the thickness of the imprinting layer by controlled/living radical polymerization (CRP). The polymeric microspheres were fully characterized and their adsorption properties were investigated. The surface molecular imprinting microspheres (SMIMs) displayed high binding affinity, good selective specificity, rapid adsorption equilibrium and satisfactory reusability. The Scatchard plots of the SMIMs could be fitted to one straight line, which suggested that there was only one kind of binding site. Furthermore, the method of combining a surface imprinting technique and CRP together can be extended to a wide range of applications for chemical sensors, drug delivery and the separation of biomacromolecules.

Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media.

A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs.

Preparation of highly cross-linked raspberry-like nano/microspheres and surface tailoring for controlled immunostimulating peptide adsorption

The surface functionalities of nanomaterials provide an invaluable resource to biomaterials science in the form of biomolecular recognition, sensing, self-assembly and drug delivery. This paper presents a one-step procedure for the facile preparation of highly cross-linked raspberry-like nano/microspheres by the dispersion polymerization of polyethylene glycol dimethacrylate and N-vinylimidazole. Ionic liquid-functionalized reactions were then conducted on the surface of the raspberry-like nano/microspheres to investigate the effects of the functional groups on the peptide adsorption in aqueous media. Various characterization methods were employed to characterize the as-prepared nano/microspheres and to track the experiment process. The results reveal that the nano/microspheres were raspberry-like, monodisperse and stable. It was also found that the adsorption of immunostimulating hexapeptide from human (IHH) was correlated with the surface properties of the ionic liquid-functionalized nano/microspheres, which demonstrated their potential use for the immobilization and release of IHH in practical application.

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

In this study, an assumption that a micromolecular monomer could easily permeate into the inside of a protein and alter its conformation, while an inflexible macromolecular monomer may interact with the surface of the protein and thus maintain the integrity of the template proteins structure was proposed for the first time and confirmed by using circular dichroism and synchronous fluorescence spectroscopy. The protein imprinted hydrogels composed of macromolecular monomers or their equivalent micromolecular monomers were characterized and carried out in the competitive adsorption and adsorption isotherm experiments. The adsorption isotherm behaviours described by the Langmuir model revealed that a higher binding affinity was observed between the template protein and imprinted hydrogels made by a macromolecular monomer. The competitive adsorption results also demonstrated the imprinted hydrogels prepared by the macromolecular monomer exhibited much better specific recognition ability to the template protein. Therefore, the strategy of using a macromolecule to imprint could effectively overcome the mutability of protein during the preparation of imprinted polymers, and consequently would promote the development of imprinting technology.

Preparation of l‐phenylalanine‐imprinted solid‐phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l‐phenylalanine from human urine

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.