A “time-frozen” technique in microchannel used for the thermodynamic studies of DNA origami

The emergence of DNA origami greatly accelerated the development of DNA nanotechnology. A thorough understanding of origami thermodynamics is very important for both fundamental studies and practical applications. These thermodynamic transitions usually take place in several seconds or even less, and are very difficult to monitor by conventional methods. Numerous tests are required to characterize the origami molecule's behaviors at different temperatures, which is very labor-intensive and time-consuming. In this paper, an axially distributed temperature gradient along a capillary was formed in a spatially varying temperature field. In such a temperature gradient, the origami molecule's thermodynamic processes occur and remain stable at every position along the capillary's microchannel. It looks like the time of the thermodynamic process is frozen along the microchannel. With this method, the origami molecule's thermodynamic characteristics at different temperatures can be obtained in a single experiment, and rapid processes can be monitored with ease by conventional methods for an adequate time period at low cost. In order to show its potential abilities, this method has been demonstrated in applications which the origami's assembly, denaturation and strand displacement are carry out in a flowing or stationary solution.