Circular DNA logic gates with strand displacement.

Circular DNA logic gates were constructed on the basis of DNA three-way branch migration. In this logic system, circular DNA was used as a basic work unit and linear single-strand DNA was used as input and output signals. Making use of the circular structure, most of the DNA-specific recognition regions were designed in a single DNA ring. Depending on accurate DNA sequence recognition and highly effective strand displacement, the logic gates yielded correct results. In addition, the positions of gold nanoparticles (AuNPs) were detected as an alternative approach to determine logic results. Thus, the accurate and tunable control of DNA/AuNPs may be applied widely in DNA nanotechnology.