Controlling the self assembly of a DNA co-polymer to make a chemical memory device

Information can be stored in chemical systems either 'actively', as steady states maintained by chemical gradients, or 'passively', as the physical arrangement of atoms/molecules in equilibrated molecules/complexes. In this work, we demonstrate how DNA can be engineered to constitute a passive chemical memory which is able to record, read and then re-record signals. The signals take the form of special DNA strands that are retrieved from the memory in the opposite order from that in which they are added. In Computer Science terms, the DNA chemical memory functions as a 'stack' data structure. The DNA device works by hybridising the signals together in a linear physical order (using Watson-Crick base pairing), and then uses DNA strand displacement to reverse this process at room temperature. Control of DNA polymerisation in this way is novel and is not reported in the DNA nanotechnology field so far.