Enantioselective Molecularly Imprinted Polymer for Tyrosine, Tryptophan, and Phenylalanine, and the Possibility of the Crop‐Circle‐Like Imprinting

AbstractMolecularly imprinted polymer (L‐MIP) for L‐tyrosine (L‐Tyr) is prepared by the complexation between quaternized poly(4‐vinylpyridine/divinylbenzene) (QVP) and poly(acrylamide‐co‐acrylic acid) (PAmA) in alkaline solution. The L‐MIP shows higher enantioselectivity for L‐isomers of tyrosine, together with tryptophan (Trp) and phenylalanine (Phe) compared to the D‐isomers of them. The sorption isotherms of the three D‐enantiomers are converged to one isotherm. It can reflect that the sorption of D‐enantiomers can be relied mainly on the common segment, ‐CH2‐CH(NH2)‐COOH, neglecting any effect of bulkier aromatic groups. The imprinted common segment can be opened on the surface of MIP from the D‐enantiomers. For the L‐enantiomers, the sorption discrepancies are depended on the size of the aromatic group implying that the phenolic moiety of L‐Tyr can be also opened. Thus, the imprinted sites are proposed to be opened on the surface of L‐MIP similar to the crop‐circle‐like. The enantioselectivity factors, αef = QL/QD, for Tyr, Trp, and Phe are 1.52, 1.30, and 1.52 for L‐ to D‐isomers, respectively. And the uptake differences between D‐ and L‐enantiomers of Tyr, Trp, and Phe are 31.8, 20.7, and 29 mg per 1 g MIP, respectively.