Brookhaven physicists have developed a way to use DNA to guide nanoparticles to stick together in a very specific way. Conveniently, the DNA strands themselves act as the binding glue to keep the particles together.
From the statement issued by Brookhaven NL press office:
The Brookhaven team has previously used DNA, the molecule that carries life’s genetic code, to link up nanoparticles in various arrangements, including 3-D nano-crystals. The idea is that nanoparticles coated with complementary strands of DNA — segments of genetic code sequence that bind only with one another like highly specific Velcro — help the nanoparticles find and stick to one another in highly specific ways. By varying the use of complementary DNA and strands that don’t match, scientists can exert precision control over the attractive and repulsive forces between the nanoparticles to achieve the desired construction. Note that the short DNA linker strands used in these studies were constructed artificially in the laboratory and don’t “code” for any proteins, as genes do.
The latest advance has been to use the DNA linkers to attach some of the DNA-coated nanoparticles to a solid surface to further constrain and control how the nanoparticles can link up. This yields even greater precision, and therefore a more predictable, reproducible high-throughput construction technique for building clusters from nanoparticles.
“When a particle is attached to a support surface, it cannot react with other molecules or particles in the same way as a free-floating particle,” explained Brookhaven physicist Oleg Gang, who led the research at the Lab’s Center for Functional Nanomaterials. This is because the support surface blocks about half of the particle’s reactive surface. Attaching a DNA linker or other particle that specifically interacts with the bound particle then allows for the rational assembly of desired particle clusters.
“By controlling the number of DNA linkers and their length, we can regulate interparticle distances and a cluster’s architecture,” said Gang. “Together with the high specificity of DNA interactions, this surface-anchored technique permits precise assembly of nano-objects into more complex structures.”
Instead of assembling millions and millions of nanoparticles into 3-D nanocrystals, as was done in the previous work, this technique allows the assembly of much smaller structures from individual particles. In the Nature Materials paper, the scientists describe the details for producing symmetrical, two-particle linkages, known as dimers, as well as small, asymmetrical clusters of particles — both with high yields and low levels of other, unwanted assemblies.
Here’s video of Oleg Gang expounding on the research:
Brookhaven press release…
Article in Nature Materials: Stepwise surface encoding for high-throughput assembly of nanoclusters
Image 1: (a) (1) DNA linker strands (squiggly lines) are used to attach DNA-coated nanoparticles to a surface. (2) Linker strands are attached to the top side of the nanoparticle. (b) (3a) A nanoparticle of a second type with complementary DNA encoding recognizes the exposed linker strands and attaches to the surface-anchored nanoparticle. (4a and 5a) The assembled structure is released from the surface support, resulting in a two-particle, dimer cluster. (c) (3b) Alternatively, the immobilized particles produced in step (a) are released from the surface, leaving the opposite-side linker strands free to bind with multiple particles (4b) to form asymmetric “Janus” clusters.
Image 2: This transmission electron micrograph shows nanoparticle dimers (two-particle clusters) assembled and released through the DNA-encoded solid-support approach.