Early explosion of DNA computing to solve combinatorial problems is now shrinking by three hardness; (1) code set design, (2) scalabfty and (3) speed and reliability. This paper proposes an implementation of Aqueous memory molecules by using light responsive modification of DNAs and show a series of feasibility experiments. We expect to overcome three difficulties since Aqueous computing is code design free, DNA sequence provides arbitrary size of address space, and light responsive reaction is fast and reliable.

We constructed a DNA machine, the state branches of which depend on input DNA oligomers. The machine is a single DNA oligomer consisting of two hairpin structures connected by a single-stranded section. The input DNA oligomers can invade a hairpin's stem via branch migration, opening the hairpin. The branching state is represented by which of the hairpins is opened. This paper describes the design of the DNA machine, an analysis of secondary structure transitions, and experimental results.