Often described as the blueprint of life, DNA contains the instructions for making every living thing from a human to a house fly.
But in recent decades, some researchers have been putting the letters of the genetic code to a different use: making tiny nanoscale computers.
In a new study, a Duke University team led by professor John Reif created strands of synthetic DNA that, when mixed together in a test tube in the right concentrations, form an analog circuit that can add, subtract and multiply as they form and break bonds.
Ref: Analog Computation by DNA Strand Displacement Circuits. ACS Synthetic Biology (1 July 2016) | DOI: 10.1021/acssynbio.6b00144
DNA circuits have been widely used to develop biological computing devices because of their high programmability and versatility. Here, we propose an architecture for the systematic construction of DNA circuits for analog computation based on DNA strand displacement. The elementary gates in our architecture include addition, subtraction, and multiplication gates. The input and output of these gates are analog, which means that they are directly represented by the concentrations of the input and output DNA strands, respectively, without requiring a threshold for converting to Boolean signals. We provide detailed domain designs and kinetic simulations of the gates to demonstrate their expected performance. On the basis of these gates, we describe how DNA circuits to compute polynomial functions of inputs can be built. Using Taylor Series and Newton Iteration methods, functions beyond the scope of polynomials can also be computed by DNA circuits built upon our architecture.