(131a) Insulator Based Dielectrophoresis for the Manipulation of DNA Origami

Self-assembled DNA nanostructures, such as DNA origamis have large potential for cutting-edge nanotechnological applications, such as DNA computing, photonic devices, or targeted diagnostics. The study of the properties for such nanostructures, controlled positioning as well as the concentration and purification is thus of utmost importance for their technological applications. In this work, we demonstrate manipulation and trapping of origami species with an insulator-based dielectrophoresis (iDEP) approach for the first time to the best of our knowledge. Specifically, we investigate the low frequency dielectrophoretic behavior of the 6-helix bundle origami in an iDEP device. We demonstrate a specific dependency of the trapping position on frequency together with a characteristic range of electric fields, in which origami DEP can be observed. We postulate that our findings can be directly applied to separation and purification of DNA origami species, as previously shown with linear DNA.

We designed an iDEP device in poly(dimethylsiloxane) to study 6-helix bundle DNA origami DEP. Via the application of potentials in the channel reservoirs, we create AC electric fields around the elliptic posts leading to electric field gradients large enough to trap the 6-helix bundle DNA origami. We observed that trapping occurs in a range of 200 V/cm to 2100 V/cm applied electric field spanning a frequency range of 60 Hz to 15 kHz. Interestingly, the frequency range under which trapping is observed is shifted to higher values for increasing applied electric field. Furthermore, the trapping area around the posts ‘shrinks’ with increasing frequency. To elucidate this phenomenon we performed numerical simulations with COMSOL Multiphysics. Our model solves the time dependent concentration distribution in the post array using the transport of diluted species module. We assume that the 6-helix bundle DNA origami is subject to diffusion, electrokinetic transport and DEP. The simulations result in a frequency dependent ‘wiggling’ migration which could be resolved experimentally due to the limitations in employed optics requiring large exposure times. However, we are able to compare the experimentally observed trapping area with the numerical simulations demonstrating that the experimentally determined distances match the theoretically predicted values in excellent agreement. This indicates that the physical origin of the variations in the trapping length are due to an overlay of electrokinetic and dielectrophoretic effects.

In summary, we demonstrated iDEP manipulation with the 6-helix bundle DNA origami. The characteristic frequency dependence on the dielectrophoretic trapping behavior was observed experimentally and substantiated with a numerical model. The variations in the trapping area around insulating structures can be explained by the electrokinetic migration of 6-helix bundle DNA origami within the trapping area. Our work provides a basis for the optimization of analytical techniques based on DEP such as fractionation and separation of origami species.