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September 13, 2007

DNA-Based Technique For better control of Assembly of Nano- and Micro-sized Particles

The method was tested separately on the nano- and micro-sized particles, and was equally successful in providing greater control than using only complementary DNA in assembling both types of particles into large or small groupings.


The method, based on designed DNA shells that coat a particle's surface, can be used to manipulate the structure - and therefore the properties and potential uses - of numerous materials that may be of interest to industry. For example, such fine-tuning of materials at the molecular level promises applications in efficient energy conversion, cell-targeted systems for drug delivery, and bio-molecular sensing for environmental monitoring and medical applications.

"Our method is unique because we attached two types of DNA with different functions to particles' surfaces," said Gang, who leads the research team. "The first type - complementary single strands of DNA - forms a double helix. The second type is non-complementary, neutral DNA, which provides a repulsive force. In contrast to previous studies in which only complementary DNA strands are attached to the particles, the addition of the repulsive force allows for regulating the size of particle clusters and the speed of their self-assembly with more precision."

"When two non-complementary DNA strands are brought together in a fixed volume that is typically occupied by one DNA strand, they compete for space," said Maye. "Thus, the DNA acts as a molecular spring, and this results in the repulsive force among particles, which we can regulate. This force allows us to more easily manipulate particles into different formations."

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