Liwei Qian

Preparation of bovine serum albumin imprinting sensitive hydrogels using ionic liquid as co-monomer and stabilizer

Through consulting the Hofmeister series, a novel biocompatible and polymerizable ionic liquid (IL) was designed and used as stabilizer and co-monomer to prepare bovine serum albumin (BSA) imprinted hydrogels. N-isopropylacrylamide (NIPA) was chosen as the assistant monomer for imparting environmental sensitivity to the hydrogels. The stabilizing effect of the IL was verified by circular dichroism. Several parameters, such as the mass ratio of the template protein, IL and crosslinker, the drying method of hydrogels and the elution method of MIHs that could affect the performance of molecular imprinted hydrogels (MIHs) were investigated. The optimum mass ratio of BSA, IL and crosslinker was found to be 200:30:6. The best drying and preferred elution method for the MIHs was achieved by slowly evaporating and washing with 0.5M NaCl solution at 15 °C, respectively. The MIHs prepared under optimized conditions were subsequently used in the adsorption isotherm, adsorption dynamics, adsorption selectivity, and competition test. The adsorption isotherm revealed that the MIHs showed the best imprinted effect at a BSA concentration of 0.2 mg mL(-1) and their imprinting factor at 2.66. The adsorption dynamic studies revealed that the adsorptive rate of the MIHs was much faster than the non-imprinted hydrogels (NIHs), and both of them could be equilibrated in 1h. The adsorption selectivity and competition tests were conducted to estimate the specific recognition property of the MIHs for BSA. The MIHs showed excellent selectivity and recognition ability to BSA. The strategy of applying biocompatible and polymerizable ILs to imprinting technology may provide a new approach for effective biomacromolecular imprinting.

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.

Separation and purification of thymopentin with molecular imprinting membrane by solid phase extraction disks

The synthesis and performance of molecularly imprinted membranes (MIMs) as a solid phase extraction packing materials for the separation and purification of thymopentin from crude samples was described. In order to increase structural selectivity and imprinting efficiency, surface-initiated ATRP and ionic liquid (1-vinyl-3-ethyl acetate imidazolium chloride) were used to prepare molecularly imprinting membranes. The results demonstrated that solid phase extraction disks stuffed by MIMs with ionic liquids as functional monomer demonstrated high isolation and purification of performance to the thymopentin. The molecular recognition of thymopentin was analyzed by using molecular modeling software.

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.

Thymopentin Magnetic Molecularly Imprinted Polymers with Room Temperature Ionic Liquids as a Functional Monomer by Surface-Initiated ATRP

Ionic liquids are also called “designer solvents.” In this article, we calculated the interaction energy of four ionic liquids with a template by molecular dynamics simulation. A simple approach was used to prepare biomacromolecule molecularly imprinted polymers for adsorbent and separation thymopentin (Tp5). In order to overcome intrinsic and increase structural selectivity, surface-initiated ATRP and ionic liquids (ILs) as functional monomer were used to prepare Fe3O4 molecularly imprinted polymers. Selective adsorption was applied to investigate the interactions between the polymers and lysine, phenylalanine, glutathione (GSH), and hemoglobin. The results demonstrated that Fe3O4 MIPs with 1-vinyl-3-ethyl acetate imidazolium chloride as functional monomer demonstrated high isolation and recognition of performance to the Tp5.

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.

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.

Superparamagnetic Molecularly Imprinting Polymers for Adsorbent and Separation Pentapeptides by Surface ATRP

A technique was used to prepare biomacromolecules imprinting polymers for adsorbent and fast separation and purification of thymopentin (Tp5). In order to overcome intrinsic and keep biomacromolecules structural, surface ATRP was used to prepare magnetic molecularly imprinted polymers (MMIPs) at mild conditions. The interactions between pentapeptides and monomers were studied by molecular dynamics. The ratio of functional monomer MMA to template pentapeptides in ethanol-water was studied by UV-Vis spectrophotometric analysis at pre-polymerization. The Fe3O4-MIPs were characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), thermogravimetry (TGA), and X-ray diffractometer (XRD) analysis. The results demonstrated that Fe3O4-MIPs possessed high isolation and identification of performance to the Tp5.

The performance optimization and specific adsorption of L-phenylalanine imprinted polymers using 1-vinyl-3-carboxymethylimidazolium chloride as functional monomer

L-Phenylalanine (L-Phe) imprinted polymers (L-MIPs) were prepared via precipitation polymerization using 1-vinyl-3-carboxymethylimidazolium chloride ([VCIM]Cl) as functional monomer, which could interact with L-Phe through electrostatic interactions, hydrogen-bonding, and π–π interactions. The morphologies of obtained polymers were observed by a scanning electron microscope, and their structures were analyzed by Fourier transform infrared spectroscopy. The effects of monomer species and molar ratio of template to functional monomer or crosslinker on adsorption capacity and imprinting factors (IFs) of polymers were investigated. The result indicated that [VCIM]Cl was preferable monomer and the optimum molar ratio of template to functional monomer and crosslinker was 1:4:16. The maximum IF of the obtained L-MIPs could reach 3.86 in 0.4 mg mL−1 L-Phe solution at 25 °C, after 8 h of adsorption and the maximum adsorption capacity of L-MIPs for L-Phe was 33.08 mg g−1. The adsorption behavior of L-Phe on the L-MIPs was construed seriously within the experimental concentration by Freundlich model and Langmuir model. In terms of the higher correlation coefficient, it was considered that the adsorption behavior of L-Phe fit Freundlich model better than Langmuir model, which means that the distribution of active sites was heterogeneous in L-MIPs. The selectivity adsorption showed L-MIPs have better specificity and selectivity for L-Phe than that of L-His and L-Trp. Finally, L-MIPs were applied to the CD and Automatic Polarimeter experiments, showing that L-MIPs had the capability of specific chiral recognition for L-Phe.