(686b) Self-Assembly of ssDNA-Amphiphiles into DNA Nanotubes with Controlled Diameters and Lengths

DNA is a popular material for constructing complex, multi-dimensional nanostructures due to its ability to organize in a precise and predictable manner. Popular approaches to create nanostructures from DNA include DNA origami, DNA tile and DNA brick assembly. An alternate approach to direct the assembly of single-stranded (ssDNA) is to conjugate a hydrophobic moiety (i.e., polymer or lipid-like tail) to the ssDNA to form an amphiphilic molecule that spontaneously self-assembles when added to aqueous solutions. However, this approach has not yet been used to create nanostructures with similar levels of complexity as those achieved by other amphiphiles. To date, the majority of structures created by the assembly of ssDNA-amphiphiles have been only spherical and cylindrical micelles. Our group showed that DNA nanotubes could be created by using molecular self-assembly of ssDNA-amphiphiles composed of a hydrophobic dialkyl tail, a polycarbon spacer and a single hydrophilic ssDNA sequence. The type of molecular spacer linking the ssDNA headgroup to a lipid-like molecule affected the amphiphile’s secondary structure and assembly, producing spherical micelles or bilayer nanotapes (flat or twisted). The nanotube structures were formed by bilayers of amphiphiles, with the hydrophobic components forming an inner layer that was shielded from the aqueous solvent by an outer layer of ssDNA. The nanotubes appeared to form via an assembly process that included transitions from twisted nanotapes to helical nanotapes to nanotubes. Amphiphiles that contained different building blocks were also created to explore their effect on the self-assembly behavior of the amphiphiles and the formation of DNA nanotubes with controlled diameters and lengths. Coarse-grained molecular dynamics simulations were employed to explain the observed changes in self-assembly of ssDNA-amphiphiles.