Ajayan, graduate student Fung Suong Ou and postdoctoral researcher Shaijumon Manikoth demonstrated that oil droplets suspended in water became encapsulated because of the structures' tendency to align their carbon ends facing the oil. By reversing the conditions -- suspending water droplets in oil the team was able to coax the gold ends to face inward and encase the water.
"For oil droplets suspended in water, the spheres give off a light yellow color because of the exposed gold ends," Ou said. "With water droplets, we observe a dark sphere due to the protruding black nanotubes."
The team is next preparing to test whether chemical modifications to the "nanobatons" could result in spheres that can both capture and break down oily chemicals. For example, they hope to attach catalysts to the water-hating ends of the nanowires that will cause compounds like trichloroethene, or TCE, to break into nontoxic constituents. Another option would be to attach drugs whose release can be controlled with an external stimulus.
"The idea is to go beyond just capturing the compound and initiate a process that will make it less toxic," Ajayan said. "We want to build upon the method of self assembly and start adding functionality so these particles can carry out tasks in the real world."
The research was supported by Rice University, Applied Materials Inc. and the New York State Foundation for Science, Technology and Innovation.
|Contact: Jade Boyd|