Molecular-imprinted nylon membranes for the permselective binding of phenylalanine as optical-resolution membrane adsorbents

Abstract

Nylon 6, nylon 6,6, and terephthalic phenylene polyamide (TPPP) were functionalized by phaseinversion molecular imprinting to add L-phenylalanine recognition ability. Formic acid containing 20 wt % nylon and 8 wt % L-phenylalanine was used as the solvent for the cast solution of the imprinting process. The resultant porous membranes behaved as membrane adsorbents that separated the L/D mixture of the substrate. The imprinted nylon 6 and nylon 6,6 presented high selectivity to the L-form substrate with respect to the TPPP membranes, but the imprinted TPPP membranes showed higher binding capacity with 0.57 μmol/g for L-phenylalanine. The apparent partition coefficients of L- and D-forms by the imprinted membranes were 6.8, 4.2, and 1.7 for nylon 6, nylon 6,6, and TPPP, respectively. The separation manner of the L- and D-forms from the mixture was also confirmed by membrane filtration under 1.5 kgf/cm 2 of applied pressure. The imprinted nylon 6, nylon 6,6, and TPPP membranes had separation factors of L- and D-phenylalanines of 1.1,1.1, and 1.2, respectively. © 2005 Wiley Periodicals, Inc.