5-nm size gold nanoparticles
wrap around the perimeter of a
DNA nanotube in a spiral pattern;
© Arizona State University
The scientists Hao Yan and Yan Liu's work responds to one of the challenges in nanotechnology and materials science, the construction of molecular-level forms in three dimensions. To do so, the research team uses gold nanoparticles, which can be placed on single-stranded DNA, compelling these flexible molecular tile arrays to bend away from the nanoparticles, curling into closed loops or forming spring-like spirals or nested rings, roughly 30 to 180 nanometers in diameter.
The gold nanoparticles, which coerce DNA strands to arc back on themselves, produce a force known as "steric hindrance," whose magnitude depends on the size of particle used. Using this steric hindrance, Yan and Liu have shown that DNA nanotubules can be specifically directed to curl into closed rings with high yield.
With the assistance of Anchi Cheng and Jonanthan Brownell at the Scripps Research Institute, they have used an imaging technique known as electron cryotomography to provide the first glimpses of the elusive 3-D architecture of DNA nanotubules. "You quickly freeze the sample in vitreous ice," Yan explains, describing the process. "This will preserve the native conformation of the structure." Subsequent imaging at various tilted angles allows the reconstruction of the three-dimensional nanostructure, with the gold particles providing enough electron density for crisp visualization.
DNA nanotubules will soon be ready to join their carbon nanotube cousins, providing flexible, resilient and manipulable structures at the molecular level. Extending control over 3-D architectures will lay the foundation for future applications in photometry, photovoltaics, touch screen and flexible displays, as well as for far-reaching biomedical advancements.
Yan and Liu believe that controlled tubular nanostructures bearing nanoparticles may be applied to the design of electrical channels for cell-cell communication or used in the construction of various nanoelectrical devices.
COMPAMED.de; Source: Arizona State University