Chiral-Discriminative gate effect in self-supporting phenylalanine-imprinted Poly(methacrylic acid-co-2-vinylpyridine-co-triethyleneglycol dimethacrylate) membrane

The solute diffusive permeability of a thin layer of a molecularly imprinted polymer (MIP) changes owing to specific binding of the MIP with a template. This phenomenon, termed the "gate effect," is applicable to biomimetic sensors. However, the mechanism underlying the gate effect is yet to be clarified. We developed a molecularly imprinted self-supporting membrane (MISSM) and carried out basic studies on the gate effect. Our model MISSM was formed by copolymerization of methacrylic acid (MAA) and 2-vinylpyridine (2-VP) (functional monomers) using triethyleneglycol dimethacrylate, TEDMA, (crosslinker) in the presence of L- (or D-) phenylalanine (template) and was approximately 50 μm thick. The amount of the template adsorbed on the MISSM was sufficiently high for easy quantification, whereas the adsorption of the enantiomer of the template was negligible. Solute permeability in the MISSM increased in the presence of the template, but was insensitive to the enantiomer of the template. The solution content in the MISSM was sensitive to the presence of the template, but was insensitive to the enantiomer of the template. Thus, our model MISSM was found to show chiral-selective gate effect and adsorption, because of which it was considered to be useful in elucidating the mechanism underlying the gate effect.