Four-bit full adder-subtracter based on DNA strand displacement

DNA strand displacement is an emerging method in the field of biological computation in recent years. It is an enzyme-free technique, which does not require any other auxiliary materials in the process of the reaction. Strand displacement reaction performs computation based on the principle of complementary base pairing. We use strand displacement systems to generated large-scale reaction network, such as circuit, and chemical reaction network. We construct molecular logic computation modules based on DSD (DNA strand displacement), including AND logic and OR logic. The logic model is simulated by visual DSD, which can be used to perform logic computation. Using DSD, we design four-bit full adder-subtracter. The method proposed in this study can provide an effective way to construct logic gate, and be used to perform dual-rail logic circuit and SAT problem, which is a potential method to solve NP problems.