Capacitive sensing of amino acids in molecularly imprinted nylon films

Molecularly imprinted polymers are important for a variety of sensing applications. We have developed capacitive elements incorporating thin nylon films prepared by spin-casting and imprinted with amino acids, and report on their frequency dependent dielectric characteristics over the range 100 Hz to 10 MHz. We find significant shifts (one decade) in the dissipation factor peaks of these samples upon removal and reinsertion of the amino acids used in their preparation. Control films remained unchanged, and other amino acids showed little binding. The use of the nylon polymer allows imprinting without the need for cross-linking agents. These structures have been used to make sensors for glutamine and alanine; the glutamine sensor shows greater specificity.