Deoxyribozyme-based half-adder.

We have constructed a solution-phase array of three deoxyribozyme-based logic gates that behaves as a half-adder. Two deoxyribozymes mimic i(1)ANDNOTi(2) and i(2)ANDNOTi(1) gates that cleave a fluorogenic substrate, reporting through an increase in fluorescence emission at 570 nm. The third deoxyribozyme mimics an i(1)ANDi(2) gate and cleaves the other fluorogenic substrate, reporting through an increase in fluorescence emission at 520 nm. Together, this system represents the first example of a decision-making enzymatic network with two inputs and two outputs. Similar systems could be applied to control autonomous therapeutic and diagnostic devices.