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.

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.

Anewmethod for determining the amount of adsorbed protein on membrane surface is developed on the basis of immunoassay using alkaline phosphotase as enzyme label and 4-nitrophenyl phosphate as substrate. Adsorption of human serum albumin (HSA) on HT Tuffryn, a kind of polysulfone microfiltration membrane, in the absence and presence of an electric field is investigated experimentally. It is shown that the adsorption of HSA on HT membrane surface is finished within 5 min and the amount of the adsorbed HSA decreases with the increase in pH but is not sensitive to salt concentration. Desorption of the adsorbed HSA from HT membrane surface can only be achieved with NaOH. Adding surfactants in HSA solution to prevent the adsorption is attempted and Tween 20 shows the best shielding function compared to polyethylene glycol 6000 and pluronic-F108. A critical concentration exists for Tween 20, below which the increase in the concentration of Tween 20 results in a corresponding reduction of adsorbed HSA. Introducing electric field into the adsorption leads to an enhanced adsorption of HSA, which appears to be a function of pH and the electric field strength.