Molecular imprinted Nylon-6 as a recognition material of amino acids

Nylon-6 was functionalized by phase inversion molecular imprinting technique to introduce l-glutamine recognition property. For imprinting l-glutamine in the polymer, 20 wt.% of Nylon-6-formic acid solution with 8 wt.% of l-glutamine template was used for the phase inversion process in water. The resulted polymer including the template molecule was washed with acetic acid solution to extract the template from the polymer. The substrate binding experiments of the l-glutamine imprinted polymer were examined in aqueous l-glutamine, d-glutamine, l-glutamic acid, and d-glutamic acid solution. The binding of l-glutamine increased with the increase of the amino acid concentration from 5 to 20 μM. The value of equilibrium binding constant for l-glutamine, KE=4.9×105 M−1, was larger than that for d-glutamine, KE=1.5×105 M−1. The recognition experiments were extended to membrane filtration and quartz-crystal microbalance response by using the imprinted Nylon-6. Evidence was also presented by FT-IR analysis that the amide–hydrogen-bonding interaction between the imprinted Nylon-6 and template was originated for the amino acid recognition.