The research appears in the Nov. 29 issue of the
Journal of the American Chemical Society (JACS 2006, 128, 15098).
Researchers believe the new method will allow them to create a wide variety of useful materials, including extra-potent cancer drugs and more efficient catalysts for the chemical industry.
The method makes use of the hydrophobic effect, a biochemical phenomena that all living creatures use to create membranes, ultra-thin barriers of fatty acids that form a strong yet dynamic sack around the cell, sealing it from the outside world. Cell membranes are one example of a micelle, a strong bilayer covering that is made of two sheets of lipid-based amphiphiles, molecules that have a water-loving, or hydrophilic, end, and a water-hating, or hydrophobic, end. Like two pieces of cellophane tape being brought together, the hydrophobic sides of the amphiphilic sheets stick to one another, forming the bilayered micelle.
"When the micelle forms, the process drives the packing of all the junction points, which connect the hydrophobic and the hydrophilic part of an amphiphile, into a high-density array," said Eugene Zubarev, the Norman Hackerman-Welch Young Investigator and assistant professor of chemistry. "By attaching a nanoparticle to the junction point of an amphiphile, we can, in effect, use micellization as a means to assemble billions and billions of individual nanoparticles into well-defined one-dimensional superstructures that are soluble in water."
Zubarev and colleagues synthesized V-shaped amphiphiles of polystyrene-b-poly(ethylene oxide) and attached two-nanometer diameter gold particles at the focal point of the V. Upon adding water and inducing micelle formation, the team found it could create tightly packed cylinders of gold nanoparticles measuring just 18 nanometers in diameter.
All micelles form in three allowable shapes – spheres, cylinders and sack-like vesicles. By varying the length of the polystyrene arm, the solvents used and the size of the gold particles, Zubarev and colleagues were able to form spheres, vesicles and vary the diameter of their cylinders, some of which grew to well-over 1,000 nanometers in length.
"We believe further manipulation of these parameters may provide an opportunity to control the optical and catalytic properties of these nanoassemblies," Zubarev said.
Source: Rice University
Related stories:
New nanoassembly technique is created
U.S. chemists at Rice University say they have discovered how to assemble gold and silver nanoparticle building blocks into larger structures.
Research helps understand factors that influence efficiency of organic-based devices
Organic-based devices, such as organic light-emitting diodes, require a transparent conductive layer with a high work function, meaning it promotes injection of electron holes into an organic layer to produce more light.
Nanoparticles assemble by millions to encase oil drops
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.
‘Mini-rivers’ may detect explosives, toxins better than other types of sensors
A casual conversation between two professors on a train from Oxford to London has led to the development of a new type of sensor that may be markedly better at sniffing out explosives, cocaine or environmental toxins than sensors now on the market.
Sticky mussels inspire biomedical engineer yet again
Mussels are delicious when cooked in a white wine broth, but they also have two other well-known qualities before they’re put in a pot: they stick to virtually all inorganic and organic surfaces, and they stick with amazing tenacity.
Nanoparticles improve delivery of medicines and diagnostics
Tiny, biodegradable particles filled with medicine may also contain answers to some of the biggest human health problems, including cancer and tuberculosis. The secret is the size of the package.
Calming your thoughts through mindfulness
Our worries. They're crescendoing like the finale of Beethoven's "Ninth": Bailouts, buyouts. Recession, depression.
Space tech helps to reach long-jump world record
German athlete Wojtek Czyz, running with a space-tech enhanced prosthetic leg, set a new world record at the Paralympics 2008 in Beijing, reaching an amazing 6.50 m and beating the previous world record by 27 cm.
