A stochastic DNA walker that traverses a microparticle surface

A DNA walker driven by hybridization reactions can traverse the surface of a DNA-coated microparticle, taking more than 30 continuous steps. Molecular machines have previously been designed that are propelled by DNAzymes1,2,3, protein enzymes4,5,6 and strand displacement7,8,9. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays10,11. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations12,13, which have been shown to lead to pattern formation14,15,16,17.