Simulation of Nanoscale Optical Signed Digit Addition Based on DNA-Strands

Recently, the interest of most researchers is to find ways to design for biomaterials with certain specifications. The proposed research introduces a new design for an arithmetic circuit which process signed-digit number by adopting conversion the input rules into an array of a strand of DNA according to a specified output for each case. In other words, gates are designed using DNA strand while the inputs are designed depending on molecular beacons (MBs). The MB is a single strand of DNA that is basically in a stable state which consists of two regions, the loop, and stem. The MB consists of 25 nucleotides, where the stem region consists of 10 nucleotides, five on each side and each side is complementary to another side. This work is divided into two parts, each part represents the code for one of the inputs. Also, each code of the sign numbers (-1, 0,1) and its complement has its own predesign pattern. Three of these pattern numbers represent inputs, while the other complement three patterns represent gates. To design the gates we start from the top and when finishing the specific value we return from the bottom and vice versa to avoid the similar design and also to make the gates take the least number of DNA strands. The outputs of each signed digit (-1, 0, 1) are indicated by optical color lights red, no light and green, respectively. The simulated results for two 4-bit signed digit number for three steps addition operation show the correctness of proposed design. The addition process is executed in parallel, so the length of the number does not exceed the calculation time.