Enzyme-Based XOR Logic Gate with Electronic Transduction of the Output Signal
Melanie Jablonski, Arshak Poghossian, Denise Molinnus, Michael Keusgen, Evgeny Katz and Michael Schöning
An enzyme-based biocatalytic system mimicking operation of an XOR logic gate was realized at an interface of a semiconductor pH-sensing device. Immobilized enzymes, penicillinase and urease, activated with penicillin and urea inputs (Inputs A and B, respectively) produced opposite pH changes decreasing and increasing pH values. In situ generated pH changes were observed only locally at the sensing interface, without affecting the bulk pH value. These local pH changes were measured by means of an enzyme-modified electrolyte-insulator-semiconductor (EIS) device operated in the constant-capacitance (ConCap) mode. Dynamic electronic measurement allowed to observe output signal changes in real time. The XOR logic gate interfaced with the electronic signal transducer can be used in future high-complexity systems, represented, for example, by reversible logic gates.