Six-helix bundle and triangle DNA origami insulator-based dielectrophoresis.

Self-assembled DNA nanostructures have large potential for nanoelectronic circuitry, targeted drug delivery, and intelligent sensing. Their applications require suitable methods for manipulation and nanoscale assembly as well as adequate concentration, purification, and separation methods. Insulator-based dielectrophoresis (iDEP) provides an efficient and matrix-free approach for manipulation of micro- and nanometer-sized objects. In order to exploit iDEP for DNA nanoassemblies, a detailed understanding of the underlying polarization and dielectrophoretic migration is essential. Here, we explore the dielectrophoretic behavior of six-helix bundle and triangle DNA origamis with identical sequence but large topological difference and reveal a characteristic frequency range of iDEP trapping. Moreover, the confinement of triangle origami in the iDEP trap required larger applied electric fields. To elucidate the observed DEP migration and trapping, we discuss polarizability models for the two species according to their structural difference complemented by numerical simulations, revealing a contribution of the electrophoretic transport of the DNA origami species in the iDEP trapping regions. The numerical model showed reasonable agreement with experiments at lower frequency. However, the extension of the iDEP trapping regions observed experimentally deviated considerably at higher frequencies. Our study demonstrates for the first time that DNA origami species can be successfully trapped and manipulated by iDEP and reveals distinctive iDEP behavior of the two DNA origamis. The experimentally observed trapping regimes will facilitate future exploration of DNA origami manipulation and assembly at the nano- and microscale as well as other applications of these nanoassemblies with iDEP.