Chiyang He

Partition of horseradish peroxidase with maintained activity in aqueous biphasic system based on ionic liquid.

Enzyme activity and partition behavior in aqueous biphasic systems (ABSs) consisting of ionic liquid (IL) and salt (IL-ABSs) were investigated to increase our understanding of IL-ABSs and shed light on their application potential as enzyme extraction system. With horseradish peroxidase (HRP) as the model enzyme, several effects of alkylimidazolium chloride-K(2)HPO(4) ABSs on activity and partition behavior of enzyme were studied including alkyl chain length of ILs and concentrations of each component. High lyotropic ILs (1-butyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium chloride) and adequate water content (>40%) were both essential for the activity maintenance of HRP in IL-ABS. 1-Butyl-3-methylimidazolium chloride ([C(4)mim]Cl) was found to be an appropriate IL for phase forming and HRP activity retaining. After optimization of phase condition, about 80% HRP amount was distributed in the IL-rich upper phase, and greater than 90% enzyme activity was obtained. Moreover, compared with the commonly used polymer-based ABSs, this [C(4)mim]Cl-ABS has a much lower viscosity, which is very beneficial to the experimental operation. Therefore, the tested IL-ABS could be considered as a potential enzyme extraction system.

Molecularly imprinted silica prepared with immiscible ionic liquid as solvent and porogen for selective recognition of testosterone

1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF(4)), an ionic liquid (IL) immiscible with water, was used as a new type of solvent and porogen for the preparation of molecularly imprinted silica. The new imprinted silica was prepared by a sacrificial spacer molecular imprinting approach with testosterone as template molecule. The new covalent monomer-template complex used in the imprinting procedure was synthesized via the reaction of 3-(triethoxysilyl)propyl isocyanate with testosterone. The imprinted silica was characterized by FT-IR spectroscopy, N(2) gas adsorption-desorption isotherm and the high-resolution transmission electron microscopy. Moreover, the selective adsorption ability of the imprinted particles towards testosterone was investigated by the steady-state binding experiment with testosterone propionate as its structural analogue. Results showed that the imprinted silica obtained in this study had relatively homogenous structure with numerous mesopores, indicating that the IL used here is an excellent solvent and satisfactory porogen for the preparation of imprinted materials. Moreover, ILs are more environmentally friendly than traditional organic solvents due to their negligible vapor pressure. The imprinted silica possesses highly specific recognition property and high binding capacity towards testosterone, showing that the new imprinting technique is relatively successful.

Molecularly Imprinted Polymer Film Grafted from Porous Silica for Selective Recognition of Testosterone

Abstract A type of testosterone‐imprinted polymer film grafted from porous silica was prepared by covalently binding azo‐initiators and then photo‐grafting. Elemental analysis and infrared (IR) spectroscopy attested the polymer formation. The material could be polymerized within 10–60 min with reproducible grafting kinetics, controllable film thickness, and obviously specific recognition ability to testosterone with the imprinting factor of 1.52. Due to its uniform size, spherical shape, controllable film thickness, and accessible sites near or at the surface, this polymer could serve as a sensing element, solid‐phase extraction material, or chromatographic stationary phase to selectively recognize or separate testosterone.

A method for coating colloidal particles with molecularly imprinted silica films

A method of coating colloidal particles with molecularly imprinted silica films of nano size is described. The imprinted film is prepared via a “sacrificial spacer” imprinting technique with testosterone as the template and silver colloidal particles as the core, and then characterized by transmission electron microscopy and infrared spectroscopy. Steady-state binding results show that the imprinted film has a highly selective recognition ability for template molecules. Moreover, due to its thickness in nanometres, the imprinted film presents a very fast kinetic profile for binding templates, with a saturation time less than 10 min. Furthermore, this technique offers a unique means of fine-tuning the thickness of imprinted materials on a core.

Extraction and determination of morphine in compound liquorice using an aqueous two-phase system of poly(ethylene glycol)/K2HPO4 coupled with HPLC

An aqueous two-phase system (ATPS) of poly(ethylene glycol) (PEG)/K(2)HPO(4) coupled with high performance liquid chromatography (HPLC) method was developed for the separation and determination of morphine in compound liquorice. Morphine and its analogs were used as model compounds to investigate influence of various factors on extraction behaviors of ATPS, such as the types and concentrations of salts, PEG molecular mass, temperature and pH. It was observed that the types of salt had much influence on extraction efficiencies of morphine and its analogs. The results indicated that hydrophobic force cooperating with hydrogen bond interaction between analytes and phases played important role in extraction process. In the optimal system of containing 0.5g PEG2000 and 1.5g K(2)HPO(4), the recoveries of the spiked standards for the analytes were all 91.7-100.3% with relative standard deviation of 1.0-3.0%. Morphine in compound liquorice was determined by the proposed method and the results were consistent with those of LC-MS method. Compared with conventional liquid-liquid extraction or solid-phase extraction, this extraction method can be completed in one operation and is low-cost. Since the entire extraction process is organic solvent-free, this new technique is environmental friendly.