Controlling DNA Orientation Using a Brush

Figure 1. Diagram showing the well-ordered zigzag structure of DNA, and the internal molecular orientation

Professor Dong Ki Yoon’s research team in the Graduate School of Nanoscience and Technology has developed a technique for producing periodic DNA zigzag structures using a common make-up brush.

The results of the research, first-authored by Ph.D. student Yun Jeong Cha and published in Advanced Materials (online, November 15, 2016), has been highlighted in the hot topics of “Liquid Crystals.”

There exist various methods for synthesizing DNA-based nanostructures, but they commonly involved complex design processes and required expensive DNA samples with regulated base sequences.

Using DNA materials extracted from salmon, the research team was able to produce a nanostructure with a well-aligned zigzag pattern at one-thousandth of the usual cost.

The team used a commercial make-up brush bought at a cosmetics store, and with it, applied the salmon DNA in one direction onto a plate, in the same way paint is brushed onto paper. Using a brush with a width of several centimeters, the team aligned DNA molecules of 2 nanometers in diameter along the direction of the brush strokes.

As the thin and dense film of DNA came into contact with air, it lost moisture. An expansive force was created between the dried film and the plate. This force interacted with the elastic force of DNA and caused undulations in the uni-directionally aligned DNA molecules, which resulted in a regular zigzag pattern.

The zigzag DNA’s base sequences could not be controlled because it was extracted from biological sources. However, it has the advantage of being cheap and readily available without compromising its structural integrity and provides a very regular and intricate structure.

This kind of well-ordered DNA structure can be used as template because it can guide or control versatile guest functional materials that are applied to its surface. For example, it can align liquid crystals used in displays, as well as metallic particles and semi-conductors. It is expected that this capacity can be extended to optoelectric devices in the future.

Professor Yoon remarked that “these findings have special implications, as they have demonstrated that various materials in nature aside from DNA, such as proteins, muscle cells, and components of bones can be applied to optoelectric devices.”

Figure 2. (Left) Unaligned DNA (Right) Aligned DNA after being brushed and dried
Figure 3. Control of the periodicity of the DNA zigzag patterns using micro-channel plates
Figure 4. Diagram representing the control of orientation of liquid crystal materials applied on a zigzag DNA template, and a polarized optical microscope image