Brookhaven Lab scientists have developed a new method for controlling the self-assembly of nanometer and micrometer-sized particles. Based on designed DNA shells that coat a particle's surface, the method can be used to manipulate the structure of numerous materials.
Such fine-tuning of materials at the molecular level may lead to numerous applications, including cell-targeted systems for drug-delivery and bio-molecular sensing for environmental monitoring or medical applications.
"Our method is unique because we attached two types of DNA to the particles' surfaces," said Brookhaven researcher Dmytro Nykypanchuk. " The first type of DNA forms a double helix, while the second type is non-complementary, neutral DNA, so it provides a repulsive force. The addition of the repulsive force allows for regulating the size of particle clusters and the speed of self-assembly with more precision."
In subsequent experiments, the researchers used DNA to guide the creation of three-dimensional, ordered, crystalline structures of nanoparticles. Engineering such 3-D structures is important for producing materials with unique properties that exist at the nanoscale, such as enhanced magnetism and improved catalytic activity.
This new assembly method relies on the attractive forces between complementary strands of DNA, but the scientists also heated the DNA-linked particles, then cooled them back to room temperature. "This 'thermal processing' allows the nanoparticles to unbind, reshuffle, and find more stable binding arrangements," Gang said.
A patent application has been filed for the technology.
This research was presented at The March 2008 American Physical Society Meeting in New Orleans, La., March 10 -14.
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