A molecularly imprinted polymeric monolith (MIPM) was prepared by in situ polymerization using styrene, glycidyl methacrylate and methacrylic acid as monomers, divinylbenzene and triallyl isocyanurate as cross-linking agents, and ceramide III as print molecule. The texture, pore size distribution, mobile phase flow characteristic, and chromatographic performance of the MIPM and a control monolith synthesized without the print molecule were examined, respectively. The results showed that using ceramide III as print molecule significantly affected the pore structure and pore distribution of the monolith, and greatly improved the retention of ceramide III and its analogues used in cosmetics as well. The retention of ceramide III on the MIPM could be reduced by increasing the ratio of chloroform to hexane in eluting buffer. The workability of the MIPM was firstly demonstrated through the separation of a model lipid mixture containing ceramide III and ergosterol, the main sterol impurity in yeast lipid extracts. The application of the ceramide III imprinted monolith to the isolation of ceramides from yeast lipid extracts was attempted and resulted in a considerable enrichment of ceramides, as shown by FTIR analysis. This indicates the potential of ceramide III imprinted monolith synthesized in the present study in the on-line solid-phase extraction of ceramides from yeast.

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.

Knowledge of the adsorption mechanism of biological molecules on hydroxyapatite (HAP) is essential to the application of HAP chromatography and to the development of HAP-based biomedical materials. Centered on the surface charge of HAP and its impacts on adsorption of proteins, the present study started with the characterization of-potential of HAP as a function of the chemical properties of solution in terms of concentration of ions of different types, ionic strength and pH. Then the adsorption of bovine serum albumin (BSA) on HAP was carried out at the same conditions to elucidate the effects of-potential on BSA adsorption and the replacement of BSA with PO4 3−in acidic buffer. A Langmuir isotherm was obtained, indicating a single layer adsorption of BSA on HAP. Finally, the apparent activation energy and the adsorption heat were interpreted from the adsorption at different temperatures. The low magnitude of both the apparent activation energy and the adsorption heat indicated that the fast adsorption of BSA on HAP was a physical adsorption process.

Refolding of native and recombinant lysozyme was accomplished by dilution with refolding buffer containing low-concentration cetyltrimethylammonium bromide (CTAB). In both cases, the use of-cyclodextrin (β-CD) was unnecessary. Centered on the interaction between CTAB and the protein being refolded, experimental studies were conducted to investigate the effect of CTAB on the refolding yield, product distribution and the refolding kinetics. A comparative study of the artificial chaperone-assisted refolding of native and recombinant lysozyme was included to generate a more comprehensive understanding of the function of CTAB in assisting protein refolding. It was shown that the formation of CTAB-denatured lysozyme complex occurred at the beginning stage of refolding effectively inhibited the formation of aggregate, leading to an improved refolding. The dissociation of this complex occurred, when lysozyme started to fold into its native conformation catalyzed by GSSG/GSH. The use of β-CD facilitated the dissociation the CTAB-protein complex and thus increased the overall rate of lysozyme refolding. The results described by present study are also helpful for the design of surfactant and the optimization of refolding process for different proteins.

The effects of a weak electric field on the growth and metabolic behavior of Enterobacter dissolvens were investigated using glucose as the sole carbon source. A direct current (DC) was applied using salt bridge electrodes and platinum electrodes. The best stimulating effects in terms of cell growth and the dehydrogenase activity (DHA) were obtained when a DC of 10mA was applied for 12 h via the platinum electrodes. In this case, the electrolysis of water was the major electrode reaction, as determined by cyclic voltammetry. The presence of the hydrogen generated a strong reductive environment and led to a reduction of NAD/NADH ratio from 7 to 3. The specific activity of dehydrogenase and glucose consumption increased 2- and 1.5-fold, respectively. The application of the DC via the platinum electrodes also led to accelerated cell death during the later stationary phase. This is possibly due to the presence of anodic intermediates including H2O2, OH• and O2•. These results provide more details for understanding the effect of a DC on E. dissolvens, a strain with potential application in the electro-remediation of PAHs contaminated soil.