Nanorod-assembled order affects diffusion rate and direction

Feb 06, 2012
Diffusional behavior of a spherical probe through static nematogens (or needles) is probed via molecular dynamics simulations. Credit: Georgia Institute of Technology

Some of the recent advancements in nanotechnology depend critically on how nanoparticles move and diffuse on a surface or in a fluid under non-ideal to extreme conditions. Georgia Tech has a team of researchers dedicated to advancing this frontier.

Rigoberto Hernandez, a professor in the School of Chemistry and , investigates these relationships by studying three-dimensional particle dynamics simulations on high-performance computers. His new findings, which focus on the movements of a spherical probe amongst static , have landed on the cover of February's The .

Hernandez and his former Ph.D. student, Ashley Tucker, assembled the rodlike scatterers in one of two states during his simulations: disordered (isotropic) and ordered (nematic). When the nanorods were disordered, pointing in various directions, Hernandez found that a particle typically diffused uniformly in all directions. When every rod pointed in the same direction, the particle, on average, diffused more in the same direction as the rods than against the grain of the rods. In this nematic state, the probe's movement mimicked the elongated shape of the scatterers. The surprise was that the sometimes diffused faster in the nematic environment than in the disordered environment. That is, the channels left open between the ordered nanorods don't just steer nanoparticles along a direction, they also enable them to speed right through.

As the of the scatterers is increased, the channels become more and more crowded. The particle diffusing through these increasingly crowded assemblies slows down dramatically in the . Nevertheless, the researchers found that the nematic scatterers continued to accommodate faster than disordered scatterers.

"These simulations bring us a step closer to creating a nanorod device that allows scientists to control the flow of nanoparticles," said Hernandez. "Blue-sky applications of such devices include the creation of new light patterns, information flow and other microscopic triggers."

For example, if scientists need a probe to diffuse in a specific direction at a particular speed, they could trigger the nanorods to move into a specified direction. When they need to change the particle's direction, scatterers could then be triggered to rearrange into a different direction. Indeed, the trigger could be the absence of sufficient nanoparticles in a given part of the device. The ensuing reordering of the nanorods would then drive a repopulation of nanoparticles that would then be available to perform a desired action, such as to stimulate light flow.

"While this NSF-funded work to better understand the motion of particles within complex arrays at the nanoscale is very fundamental," Hernandez says, "it has significant long-term implications on device fabrication and performance at such scales. It's fun to think about and provides great training for my students."

Explore further: Tissue regeneration using anti-inflammatory nanomolecules

Related Stories

Researchers discover new way to control particle motion

Mar 17, 2008

Chemical engineers at The University of Texas at Austin have discovered a new way to control the motion of fluid particles through tiny channels, potentially aiding the development of micro- and nano-scale technologies such ...

On the nanoscale, particles flow in unexpected ways

Oct 25, 2011

Researchers studying how fluids travel through nanoscale channels were surprised to discover that the fluids don't flow equally well in all directions. Contrary to the behavior in the macroscale world, the researchers discovered ...

Recommended for you

Tissue regeneration using anti-inflammatory nanomolecules

Aug 22, 2014

Anyone who has suffered an injury can probably remember the after-effects, including pain, swelling or redness. These are signs that the body is fighting back against the injury. When tissue in the body is damaged, biological ...

Cut flowers last longer with silver nanotechnology

Aug 21, 2014

Once cut and dunked in a vase of water, flowers are susceptible to bacterial growth that shortens the length of time one has to enjoy the blooms. A few silver nanoparticles sprinkled into the water, might be the answer to ...

Relaxing DNA strands by using nano-channels

Aug 20, 2014

A simple and effective way of unravelling the often tangled mass of DNA is to 'thread' the strand into a nano-channel. A study carried out with the participation of the International School for Advanced Studies ...

Сalculations with nanoscale smart particles

Aug 19, 2014

Researchers from the Institute of General Physics of the Russian Academy of Sciences, the Institute of Bioorganic Chemistry of the Russian Academy of Sciences and MIPT have made an important step towards ...

User comments : 0