Supercritical CO 2 (ScCO 2 ) has been used to prepare molecularly imprinted polymers of poly(styreneco-maleic acid) (PSMA) for targeted uracil (URA). The condition of ScCO 2 was on 16 MPa between 35 and 508C. The resultant imprinted membranes prepared at 35 and 508C bound URA with 9.2 6 0.10 and 12.6 6 0.06 lmol g 21 , respectively. Competitive binding studies were undertaken in binary substrate solution containing each of URA/ DMURA, URA/Thymine, and URA/Cytosine with 2 lM. The URA imprinted membrane showed high separation factor (a) with 17 for both URA/DMURA and URA/Thymine and for URA/Cytosine, a 5 13. Results strongly suggested that the URA imprinted membrane had effective selectivity hydrogen bonding to separately bind in the binary components to the template. Effect of organic solvents on the URA imprinting in ScCO 2 was also studied, in addition to comparison of properties with those obtained in both ScCO 2 and water. Evidence presented that ScCO 2 medium was effective to prepare the URA imprinted membrane. We discussed that ScCO 2 fluid was efficient to fix the shape of URA template into the PSMA membrane through hydrogen bonding.

Phase separation of poly(acrylonitrile-co-methacrylic acid) in compressed liquid CO(2) resulted in formation of a porous imprinted membrane which preferentially adsorbed uracil (URA). The cross-section of the membrane was observed by SEM, which revealed its porous structure. The mechanical strength of the membrane indicated formation of a rigid matrix with high tensile strength (4.4 N mm(-2)). The imprinted membranes bound highly selectively to URA (12.8 micromol g(-1)) but binding to dimethyluracil (DMURA), thymine, and cytosine was less (0.7, 0.8, and 0.9 micromol g(-1), respectively). When DMURA was similarly used to prepare an imprinted membrane in liquid CO(2) there was less binding of DMURA to the imprinted membrane obtained. The URA-imprinted membranes were evaluated by IR spectroscopy before and after URA extraction. The results indicated that hydrogen bonding was the mechanism of binding of URA to the imprinted membrane. Competitive binding studies were performed with binary mixtures of URA and its analogues. The URA-imprinted membrane enabled good separation of URA from cytosine, DMURA, and thymine, with separation factors of 3.0, 3.8, and 2.5, respectively. It was confirmed that the compressed liquid CO(2) contributed to efficient formation of template substrate sites in the URA-imprinted membrane.

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