DNA origami as never before


Rebecca Pool

Wednesday, July 18, 2018 - 11:30
Image: Nanostructures built using DNA origami alongside diatoms, single-celled algae enshrined in an intricately-structured silica cell wall.
Using DNA origami, US-based researchers have designed a range of breathtakingly beautiful diatom-like, DNA-silica hybrid nanostructures.
These latest complex silica nanomaterials from Professor Hao Yan from Arizona State University, and colleagues, are up to ten times tougher than conventional DNA origami scaffolds and open the door to the widespread development of strong, biomimetic silica nanostructures. 
DNA origami, relies on the base-pairing properties of DNA's four nucleotides, with the ladder-like structure of the DNA double-helix forming when complementary strands of nucleotides bond with each other.
This predictable behavior can be exploited in order to produce a virtually limitless variety of engineered shapes.
These can be designed in advance, with nanostructures then self-assembling in a test tube.
"Here, we demonstrated that the right chemistry can be developed to produce DNA-silica hybrid materials that faithfully replicate the complex geometric information of a wide range of different DNA origami scaffolds," says Yan. "Our findings established a general method for creating biomimetic silica nanostructures."
The researchers designed and constructed 2D crosses, squares, triangles and DOS-diatom honeycomb shapes as well as 3D cubes, tetrahedrons, hemispheres, toroid and ellipsoid forms, occurring as single units or lattices, ranging in size from 10 to 1000 nm.
Once the DNA frameworks were complete, clusters of silica particles carrying a positive charge were drawn electrostatically to the surfaces of the electrically negative DNA shapes.
This process took several days and the researchers captured stunning SEM and TEM images, revealing accurate and efficient diatom-like silicification.
3D cube made using DNA Origami Silicification, which deposits a fine layer of silica onto the DNA origami framework. [Yan Lab]
The researchers also used atomic force microscopy to measure the resistance to breakage of their silica-augmented DNA nanostructures.
Like their natural counterparts, these forms showed far greater strength and resilience, displaying a 10-fold increase in the forces they could withstand, compared with the unsilicated designs, while retaining considerable flexibility.
The study also shows that the enhanced rigidity of the hybrid nanostructures increases with growth time.
A final experiment involved the design of a new 3D tetrahedral nanostructure using gold nanorods as supportive struts for a DOS fabricated device.
This novel structure was able to faithfully retain its shape compared with a similar structure lacking silication.
The work could ultimately have far-reaching applications in new optical systems, semiconductor nanolithography, nano-electronics, nano-robotics and medical applications, including drug delivery.
Research is published in Nature.
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