In a development that could lead to new technologies for cleaning up oil spills and polluted groundwater, scientists at Rice University have shown how tiny, stick-shaped particles of metal and carbon can trap oil droplets in water by spontaneously assembling into bag-like sacs.
The tiny particles were found to assemble spontaneously by the tens of millions into spherical sacs as large as BB pellets around droplets of oil in water. In addition, the scientists found that ultraviolet light and magnetic fields could be used to flip the nanoparticles, causing the bags to instantly turn inside out and release their cargo -- a feature that could ultimately be handy for delivering drugs.
"The core of the nanotechnology revolution lies in designing inorganic nanoparticles that can self-assemble into larger structures like a 'smart dust' that performs different functions in the world – for example, cleaning up pollution," said lead research Pulickel Ajayan, Rice's Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science. "Our approach brings the concept of self-assembling, functional nanomaterials one step closer to reality."
The research was published online today by the American Chemical Society's journal Nano Letters.
The multisegmented nanowires, akin to "nanoscale batons," were made by connecting two nanomaterials with different properties, much like an eraser is attached to the end of a wooden pencil. In the study, the researchers started with carbon nanotubes -- hollow tubes of pure carbon. Atop the nanotubes, they added short segments of gold. Ajayan said that by adding various other segments -- like sections of nickel or other materials -- the researchers can create truly multifunctional nanostructures.
The tendency of these nanobatons to assemble in water-oil mixtures derives from basic chemistry. The gold end of the wire is water-loving, or hydrophilic, while the carbon end is water-averse, or hydrophobic. The thin, water-tight sacs that surround all living cells are formed by interlocking arrangements of hydrophilic and hydrophobic chemicals, and the sac-like structures created in the study are very similar.
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.
Jade Boyd | EurekAlert!
A new 'cool' blue
17.01.2020 | American Chemical Society
Neuromuscular organoid: It’s contracting!
17.01.2020 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft
Styrofoam or copper - both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.
Thermal insulation and thermal conduction play a crucial role in our everyday lives - from computer processors, where it is important to dissipate heat as...
In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.
The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...
Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...
Researchers from the University Hospital Zurich, ETH Zurich, Wyss Zurich and the University of Zurich have developed a machine that repairs injured human livers and keep them alive outside the body for one week. This breakthrough may increase the number of available organs for transplantation saving many lives of patients with severe liver diseases or cancer.
Until now, livers could be stored safely outside the body for only a few hours. With the novel perfusion technology, livers - and even injured livers - can now...
A balloon-borne scientific instrument designed to study the origin of cosmic rays is taking its second turn high above the continent of Antarctica three and a half weeks after its launch.
SuperTIGER (Super Trans-Iron Galactic Element Recorder) is designed to measure the rare, heavy elements in cosmic rays that hold clues about their origins...
16.01.2020 | Event News
15.01.2020 | Event News
07.01.2020 | Event News
17.01.2020 | Life Sciences
17.01.2020 | Power and Electrical Engineering
17.01.2020 | Life Sciences