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Posted: Nov 14, 2011

Controlled growth of DNA nanomaterials opens new applications in nanoelectronics

(Nanowerk News) DNA-based nanomaterials are key precursors for the bottom-up fabrication of a range of high-performance nanoscale devices such as biosensors and nanoelectronics because of their ability to self-assemble into well-defined structures. However, the lack of control encountered during the deposition of these nanostructures on surfaces has hampered their application in practical devices.
Sung Ha Park, Yonghan Roh and colleagues from Sungkyunkwan University and the Samsung Advanced Institute of Technology in Korea have now developed a surface-promoted method that allows for the precise control of DNA crystal growth on silica substrates ("Coverage Control of DNA Crystals Grown by Silica Assistance").
DNA crystals grown by a silica-assisted method on patterned silica substrates
DNA crystals grown by a silica-assisted method on patterned silica substrates. (© 2011 Wiley-VCH)
Although the self-organizing properties of DNA have been widely exploited for constructing nanoelectronics, applications have been restricted to single- and double-stranded DNA. However, extending this technique to the growth of heteromaterials on substrates in order to add functionality has proved difficult due to the lack of control over the spatial orientation of the DNA.
To solve this problem, Park and Roh's team used artificially designed DNA crystals with highly periodic arrangements. Using standard silica-based semiconductor techniques, their approach gives complete control over surface coverage, from 0 to 100%, and the exact location of DNA crystal growth.
The silica-assisted growth method developed by the researchers involves treating a silica substrate with a buffer solution containing magnesium ions and then immersing the substrate in a solution containing DNA. Heating the solution to 95 C and then cooling to room temperature over 24 hours allowed the DNA to hybridize with the substrate and form well-ordered DNA crystals.
The magnesium ions on the silica surface provide anchor points for the DNA nanostructures, and pretreatment of the substrate lowers the energy required for the DNA crystals to nucleate. "This allows the formation of crystals at DNA concentrations lower than that needed even in free solution methods," says Park.
By patterning the silica substrate in advance using standard lithography techniques, the researchers were able to produce patterns of DNA crystal (see image) that could form the basis for nanoelectronics in applications such as organic light-emitting diodes and solar cells. "Our method provides a route to a wide range of applications because the crystals could be easily functionalized with nanowires, nanoparticles and even polymers," says Park.
Source: Tokyo Institute of Technology
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