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2006年07月10日

【期刊论文】computational and experimental investigation of the interaction between the template molecule and the functional monomer used in the molecularly imprinted polymer

刘铮, Wenguo Donga, Ming Yan a, Minlian Zhang a, Zheng Liu a, ∗, Yanmei Li b

Analytica Chimica Acta 542(2005)186-192,-0001,():

-1年11月30日

摘要

A computational approach to screening monomer for preparing molecularly imprinted polymer (MIP) was proposed, using the binding energy, E, of a template molecule and a monomer as a measure of their interaction. For a specified template molecule, a monomer of higher E is suitable for preparing the MIP. To examine the validity of this approach, theophylline (THO) was chosen as the template molecule and methacrylic acid (MAA), acrylamide (AA) and 2-(trifluoromethyl)acrylic acid (TFMAA) were as the functional monomers, respectively. Density functional theory (DFT) at B3LYP/6-31+G**//B3LYP/3-21G level was used to calculate E. It was shown that TFMAA gave the largest E whileAAgave the smallest. The details of the interaction between the THO with these monomers were also given by this computing approach. The adsorption of THO on the MIP synthesized using different monomers was studied. The MIP synthesized using TFMAA as monomer showed the highest selectivity to THO while the MIP from AA gave the lowest, as predicted from the E calculation. 1H NMR spectroscopy showed that, compared to MAA and AA, a stronger H-bond interaction is formed between TFMAA and THO. FT-IR analysis of the MIPs prepared using these three monomers confirmed the existence of C O and O H groups, which forms H-bond with THO. The results described above have given an insight into the interaction between THO and the monomers, and shown the use of E to facilitate the selection of monomers for the synthesis of MIP.

Molecularly imprinted polymer, Binding energy, Density functional theory, Theophylline

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2006年07月10日

【期刊论文】Mass transport characteristics and chromatographic behavior of preparative electrochromatography on hydroxyapatite

刘铮, Gang Yin a, Zheng Liu a, *, Rui Zhou b, Jin Zhan a, Jun Wang a, Naiju Yuan a

G. Yin et al./J. Chromatogr. A 918(2001)393-399,-0001,():

-1年11月30日

摘要

Introducing an electric field into chromatography on hydroxyapatite (HAP) was attempted in order to enhance mass transfer and separation performance. A membrane spaced multicompartment electrolyzer was developed for electrochromatography on HAP. The high performance of liquid transport by electroosmotic flux was identified and described in terms of dynamic electroosmotic pressure. The application of the electric field resulted in an improved adsorption of bovine serum albumin as shown by the breakthrough curve as function of the electric field. An improved elution was also obtained in the presence of the electric field. The results show that electroosmosis is a powerful tool of liquid transport and dispersion in a packed bed of fine particles and has potential in the large-scale chromatography of biological molecules.

Electroosmosis, Mass transport, Hydroxyapatite, Bovine serum albumin

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2006年07月10日

【期刊论文】Oscillatory electroosmosis-enhanced intra/inter-particle liquid transport and its primary applications in the preparative electrochromatography of proteins

刘铮, Zheng Liu*, Gang Yin, Shaohua Feng, Donghai Wang, Fuxin Ding, Naiju Yuan

J. Chromatogr. A 921(2001)93-98,-0001,():

-1年11月30日

摘要

The concept of generating an oscillatory electroosmotic flux inside the porous particle to enhance the intra-particle mass transport was presented and a new kind of electrochromatography carried out in a five-compartment electrolyzer were developed. The adsorbent was packed in the central compartment, while the neighboring compartments were used as the elution compartments and the electrode compartments, respectively. Chromatographic separations of human serum albumin on Blue Sepharose Fast Flow, bovine serum albumin (BSA) on DEAE–Sepharose Fast Flow, and BSA on ydroxyapatite were carried out, respectively. The adsorption isotherms were shown to be independent of electric field, while the increase in the electric field strength resulted in a linear increase in the magnitude of electroosmotic flux and the improvement of the breakthrough behavior in all cases. The experiment results have demonstrated the effectiveness of the oscillatory electroosmosis in enhancing intra- and inter-particle mass transport and its high potential to large-scale hromatography.

Electrochromatography, Affinity electrochromatography, Electroosmosis, Preparative chromatography, Proteins, Albumin

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2006年07月10日

【期刊论文】The mechanism of PNIPAAm-assisted refolding of lysozyme denatured by urea

刘铮, Diannan Lua, Zhixia Liua, Minlian Zhanga, Zheng Liua, ∗, Haimeng Zhoub

Biochemical Engineering Journal 24(2005)55-64,-0001,():

-1年11月30日

摘要

The molecular interaction of a temperature stimuli-responsive polymer, poly-N-isopropyl acrylamide (PNIPAAm), with lysozyme of different status was studied with an emphasis on the application of PNIPAAm for protein refolding. The refolding of lysozyme was performed by directly diluting denatured lysozyme into a refolding buffer containing PNIPAAm, in which PNIPAAm with the weight average molecular weight of 22,000, denoted as M-PNI, gave the best refolding yield in terms of the recovery of lysozyme activity. The interaction between M-PNI and lysozyme was investigated using non-reductive SDS–PAGE, circular dichroism (CD), fluorescence emission spectroscopy, and reverse phase HPLC. It was shown that the use of M-PNI increased the secondary structures of lysozyme and reduced the formation of protein aggregate. The correctly folded lysozyme has a weaker hydrophobicity compared to the denatured lysozyme. The PNIPAAm-lysozyme complex dissociates once lysozyme is correctly folded. The increase in the operational temperature leads to increases in both the refolding yield and the apparent rate of refolding. Based on above experimental results, a kinetic model of the refolding, both with and without PNIPAAm, was determined and a molecular view of lysozyme refolding using PNIPAAm was presented.

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2006年07月10日

【期刊论文】Surfactant Enhanced Electroremediation of Phenanthrene"

刘铮, SHE Peng(a, LIU Zhenga*, *, DING Ftincina, YANG JIANGANGb, and LIU Xianga,

Chinese J. Chem. Eng, 11 (1): 73-78 (2003),-0001,():

-1年11月30日

摘要

Removal of hydrophobic organic contaminants (HOCs) from soil of low permeability by electroremedia-tion was investigated by using phenanthrene and kaolinite as a model system. Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene. The effects of pH on the assorption of phenanthrene and Tween 80 on kaolinite and he magnitude of S-potential of kaolinite were examined. respectively. The effects of electric field strength indicated by electric current on the electroremediation investigated. respectively Incase of an electric field of 25mA applied for 72 hours, overs 90% of phenanthrene was removed from 424g (dry mass) of kaolinite at an energy consumption of 0.148 kW.h. The experimental results described in prcsent study show that the addition of surfactant into purging solution greatlky enhances the removal of HOCs by electroremediation.

electrolemediation, phenanthrene,, polycyclic aromatic hydrocarbon,, kaolinite,, ele ctroosmosis

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    清华大学,北京

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