Painting with DNA Materials
A research team from the Graduate School of Nanoscience and Technology at KAIST led by Professor Dong Ki Yoon, has successfully fabricated nanometer scaled DNA (deoxyribonucleic acid) structures with a centimeter-scaled brush using inexpensive and crude DNA materials that were extracted from salmon sperm. This achievement can give a hint to the use of natural and abundant DNA sources and other biomaterials for potential fabrication applications due to their highly regular periodicity at the nanometer scale.
DNA is one of the most abundant biomaterials in nature. It is found in all living organisms and has unique characteristics. Its double helix design that involves precise dimensions and its surface which is exceptionally dense with negative charges enables for its rich chemical properties to be exploited in a range of applications, beyond the original biological intentions. Based on these characteristics, DNA has been considered and used as a building block for “origami” and textile art at the nanometer scale. However, synthesized DNA materials can be rather costly and, therefore, inaccessible for example in schools for educational purposes.
A research team in the GSNT at KAIST found that painting an interesting picture using the DNA material as ink and glass plate as canvas is possible and demonstrated this technique. To achieve this, crude DNA material extracted from salmon sperm was used, keeping the total cost to prepare one-slide glass with this material under 1 USD. Even though cheap and crude DNA material was used, the dimensions achieved using this method were not different when compared with more expensive, synthetic DNA materials. Particularly, a normal makeup brush commonly available in convenience stores (e.g. Olive Young) was employed. This signifies that anyone can potentially use, mold, and make craft work with DNA to create various nanostructures. Dong Ki Yoon and coworkers aligned the DNA unidirectionally along the brushing direction to achieve periodic zigzags; this was made possible due to the competition between the elasticity of DNA and the dilative force which occurred during the evaporation of the solvent (water). The resultant samples (figure) can host liquid crystal molecules due to the rich chemical properties and topography of DNA.
In detail, to make well-aligned patterns of DNA mentioned above, the DNA aqueous solution with a columnar liquid crystal phase was used. When a highly concentrated DNA solution (~200 mg/ml) was dropped on a glass substrate, a short-range oriented columnar structure was obtained. When the DNA solution was sheared by the brush, the DNA chains in each band formed a zigzag pattern over a large area by undulation of columnar aggregates of the DNA. The DNA chains at first were oriented parallel with the shearing direction. This DNA film had fine grooves in the direction parallel to the shearing direction, which resulted from the brushing process. As the water evaporated, the contact lines of these groove receded which induced the dilative stress and an increase of a local density of the DNA. Therefore, the undulation of the DNA columnar structures were generated by a competition between the dilative stress and a collective behavior of DNA elasticity. As shown in the polarized optical images and schematic images below, there exist defect walls between the domains that are simply distinguished by colors, in which the DNA chain direction is suddenly changed to form the domain boundary. The domain walls are not only two dimensionally distinctive lines but also topographically patterned surfaces that are used to grab the nanoparticles or defect lines of LC structures.
* Lab information