Qiliang Deng

Preparation of a new type of affinity materials combining metal coordination with molecular imprinting

A new approach, combining metal-coordination with molecular imprinting technology, was developed to prepare protein-affinity materials, which showed higher specific recognition ability towards the target protein than those prepared using either metal-coordination or molecular imprinting technology.

Preparation and evaluation of molecularly imprinted ionic liquids polymer as sorbent for on-line solid-phase extraction of chlorsulfuron in environmental water samples

In this report, vinylimidazolium ionic liquid as a functional monomer for preparation of chlorsulfuron (CS) imprinted polymers were first studied. The imprinted materials showed high selectivity for CS, and fast kinetics so that adsorption equilibrium was achieved within 5 min. These materials have been further employed to detect trace CS from water samples by online preconcentration coupled with HPLC. The sorbent offered good linearity (0.005-30 μg L(-1), r(2)>0.99) for on-line solid-phase extraction of trace chlorsulfuron. Under the optimal experimental conditions, the recovery for chlorsulfuron was in the range of 81.0-110.1% for the water samples, with RSDs ranging from 1.2 to 7.6%.

Highly sensitive fluorescent sensing for water based on poly(m-aminobenzoic acid)

Fluorescent conjugated polymer, poly(3-aminobenzoic acid), as a new class of fluorescence sensor for detection of trace amounts of water in organic solvents was developed. This sensor exhibits extraordinarily high sensitivity with a detection limit as low as 0.008 wt% for water in DMF.

Preparation, characterization and application of organic-inorganic hybrid ractopamine multi-template molecularly imprinted capillary monolithic column.

Four isomers of ractopamine used as multi-template molecule, a molecularly imprinted capillary monolithic column was prepared by organic-inorganic hybrid method. The prepared imprinting capillary monolithic columns were characterized by SEM and FTIR, evaluated under capillary electrochromatograhy and the effect of electroosmotic flow and selectivity were studied in detail. It was found that the prepared imprinted monolithic column had good flow-through property when the ratio of methanol and toluene was 3:2. The result indicated that the imprinted monolithic column has good selectivity for four isomers of ractopamine, and under the conditions of pH value of buffer solution was 7 and 10% acetonitrile content in buffer, four isomers of ractopamine could be separated completely.

Facile synthesis of Fe3O4@TiO2–ZrO2 and its application in phosphopeptide enrichment

Herein, a novel type of binary-metal-oxide-coated magnetic microspheres-titanium dioxide-zirconium dioxide-coated magnetic Fe3O4 microspheres (Fe3O4@TiO2-ZrO2)-were prepared and employed to selectively capture phosphopeptides for the first time. The synthesized Fe3O4@TiO2-ZrO2 magnetic functional microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), N2 adsorption-desorption technique and magnetic measurements. Experimental conditions for trapping phosphopeptides were optimized by using β-casein as the standard protein. Under the optimal conditions, the mixture of β-casein and bovine serum albumin (BSA) with different proportions was considered as the semi-complex sample and non-fat milk as the real biological sample to evaluate the capability for trapping phosphopeptides. The results revealed that Fe3O4@TiO2-ZrO2 not only concentrated more phosphopeptides than Fe3O4@TiO2 or Fe3O4@ZrO2, but also enriched both the monophosphopeptides and multiphosphopeptides efficiently. The detection limit of this approach for the enrichment of phosphopeptides by Fe3O4@ZrO2-TiO2 microspheres from the tryptic products of β-casein was 500 pM (500 μL).

Molecularly imprinted upconversion nanoparticles for highly selective and sensitive sensing of Cytochrome c.

A novel method combined the high selectivity of molecular imprinting technology with the strong fluorescence property of upconversion nanoparticles (UCNPs) for sensing of Cytochrome c (Cyt c) was proposed. The molecularly imprinted material-coated upconversion nanoparticles (UCNPs@MIP) were obtained by in situ coating Cyt c imprinted materials to the surface of the carboxyl modified UCNPs through sol-gel technique. The structure and component of the prepared UCNPs@MIP was investigated by transmission electron microscopy (TEM), power X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDXA) and X-ray photoelectron spectroscopic (XPS). The TEM showed the diameter of UCNPs was 40 nm, and thickness of MIP was 5-10nm. The fluorescence intensity of UCNPs@MIP reduced gradually with the increase of Cyt c concentration. Under optimum conditions, the imprinting factor is 3.19, and the UCNPs@MIP showed selective recognition for Cyt c among other proteins such as bovine serum albumin (BSA) and Lysozyme (Lyz). Therefore, this new method for sensing protein is very promising for future applications.

A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography.

A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm(+)Cl(-)) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0-12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ~6.8 μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ~147,000 plates m(-1) for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.

Guanidinium functionalized superparamagnetic silica spheres for selective enrichment of phosphopeptides and intact phosphoproteins from complex mixtures

Phosphorylation of protein regulates nearly all biological processes in nature. The development of enrichment techniques for phosphorylated proteins is vital to systematic identification and characterization of phosphoproteins. Here, a general strategy for highly efficient capture of intact phosphorylated proteins from protein mixtures has been developed by using guanidine functionalized superparamagnetic microspheres (denoted as Fe3O4@SiO2@GDN). The Fe3O4@SiO2@GDN was prepared by modifying Fe3O4@SiO2 with 3-guanidopropyl triethoxysilane as a functionalization monomer. The resulting materials could specifically and selectively recognize phosphoproteins and showed high binding capacities for model phosphoproteins (78.8 mg g-1 for ovalbumin (OVA) and 59.6 mg g-1 for β-casein (β-Cas), respectively). The feasibility of the resulting material for phosphoprotein enrichment has also been demonstrated by selectively binding and capturing phosphoproteins from complex protein mixtures and real samples (milk, egg, and tissue protein extract from a mouse liver), respectively. In addition, the selective enrichment of phosphopeptides has also been investigated. The proposed technique showed application potential for phosphoprotein and phosphopeptide enrichment.

Upconversion fluorescence metal-organic frameworks thermo-sensitive imprinted polymer for enrichment and sensing protein

A novel fluorescence material with thermo-sensitive for the enrichment and sensing of protein was successfully prepared by combining molecular imprinting technology with upconversion nanoparticles (UCNPs) and metal-organic frameworks (MOFs). Herein, the UCNPs acted as signal reporter for composite materials because of its excellent fluorescence property and chemical stability. MOFs were introduced to molecularly imprinted polymer (MIP) due to its high specific surface area which increases the rate of mass transfer relative to that of traditional bulk MIP. The thermo-sensitive imprinted material which allows for swelling and shrinking with response to temperature changes was prepared by choosing Bovine hemoglobin (BHB) as the template, N-isopropyl acrylamide (NIPAAM) as the temperature-sensitive functional monomer and N,N-methylenebisacrylamide (MBA) as the cross-linker. The recognition characterizations of imprinted material-coated UCNPs/MOFs (UCNPs/MOFs/MIP) were evaluated, and the results showed that the fluorescence intensity of UCNPs/MOFs/MIP reduced gradually with the increase of BHB concentration. The fluorescence material was response to the temperature. The adsorption capacity was as much as 167.6 mg/g at 28°C and 101.2mg/g at 44°C, which was higher than that of traditional MIP. Therefore, this new fluorescence material for enrichment and sensing protein is very promising for future applications.

Macroporous molecularly imprinted monolithic polymer columns for protein recognition by liquid chromatography.

Macroporous cytochrome c (cyc)-imprinted monolithic polyarylamide columns were prepared, and applied for the template protein recognition by HPLC. With cyc (18.8 mg) as template, the imprinted monolithic materials were in situ polymerized in an HPLC column tube, with methacrylamide (450 mg), methacrylic acid (15.8 mg), piperazine diacrylamide (720 mg) and ammonium sulfate (390 mg) dissolved in 5 mL of phosphate buffer (pH 7.4), initiated by ammonium persulfate and TEMED. After the reaction, cyc was removed with acetic acid (10%, v/v) containing 10% w/v SDS. The non-imprinted monolithic column was prepared under the same procedure except without cyc. Retention of cyc and its competitive protein, lysozyme (lys), on molecular-imprinting polymer (MIP) and non-imprinted polymer columns was studied. When the pH value of mobile phase was 4.0, on MIP column, the retention factors of cyc and lys were 2.0 and 1.3, respectively. However, those on non-imprinted polymer column were very similar, both as 1.1. Even in competitive environment, a mixture of cyc and lys could be separated on MIP column under gradient elution, with resolution as 1.2. These results indicate that protein-imprinted monolithic polymer columns could offer obvious affinity and specific recognition to the template protein.