Renyuan Song

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.

Molecularly imprinted solid-phase extraction of glutathione from urine samples

Molecularly imprinted polymer (MIP) particles for glutathione were synthesized through iniferter-controlled living radical precipitation polymerization (IRPP) under ultraviolet radiation at ambient temperature. Static adsorption, solid-phase extraction, and high-performance liquid chromatography were carried out to evaluate the adsorption properties and selective recognition characteristics of the polymers for glutathione and its structural analogs. The obtained IRPP-MIP particles exhibited a regularly spherical shape, rapid binding kinetics, high imprinting factor, and high selectivity compared with the MIP particles prepared using traditional free-radical precipitation polymerization. The selective separation and enrichment of glutathione from the mixture of glycyl-glycine and glutathione disulfide could be achieved on the IRPP-MIP cartridge. The recoveries of glutathione, glycyl-glycine, and glutathione disulfide were 95.6% ± 3.65%, 29.5% ± 1.26%, and 49.9% ± 1.71%, respectively. The detection limit (S/N=3) of glutathione was 0.5 mg·L(-1). The relative standard deviations (RSDs) for 10 replicate detections of 50 mg·L(-1) of glutathione were 5.76%, and the linear range of the calibration curve was 0.5 mg·L(-1) to 200 mg·L(-1) under optimized conditions. The proposed approach was successfully applied to determine glutathione in spiked human urine samples with recoveries of 90.24% to 96.20% and RSDs of 0.48% to 5.67%.

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.

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.

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.

Synthesis of glutathione imprinted polymer particles via controlled living radical precipitation polymerization

A general protocol was described for fabricating uniform molecularly imprinted polymer (MIP) particles via controlled living radical precipitation polymerization at ambient temperature. By adopting glutathione as model template, benzyl dithiocarbamate as iniferter agent, 4-vinylpyridine as monomer, and ethylene glycol dimethacrylate as cross-linker, it is demonstrated that the polymerization parameters including the iniferter concentration, monomer loading and molar ratio of cross-linker to functional monomer have profound effect on the final particle size and recognition property of the MIP particles. The batch static binding experiments were carried out to estimate the adsorption kinetics, adsorption isotherms and selective recognition of the MIP particles. The adsorption behavior followed the pseudo-second order kinetic model, revealing that the process was chemically carried out. Two adsorption isotherm models were applied to analyze equilibrium data, obtaining the best description by Langmuir isotherm model. In addition, the MIP particles also could selectively recognize glutathione over similar analogs, indicating the possibility for the separation and enrichment of the template from complicated matrices.