A picture from DNA
Van Gogh's "Starry Night" was recreated using DNA origami
Vladimir Korolev, N+1
Chemists from the California Institute of Technology reproduced the picture "Starry Night" using DNA origami. To do this, scientists have developed a technology that allows placing pre-determined amounts of phosphors on the surface of photonic crystals. DNA molecules in it play the role of adapters on which dye molecules were attached. The study was published in the journal Nature (Gopinath et al., Engineering and mapping nanocavity emission via precision placement of DNA origami), briefly reported by Gizmodo (Here's Van Gogh's Starry Night Recreated with 'DNA Origami').
A fragment of the recreated painting (here and below are the drawings from the article in Nature)
DNA origami is a technique that allows you to create nanoobjects from long DNA molecules with programmed properties: the shape and location of functional sections. It is based on the principle of complementarity, which describes the structure of double-stranded DNA. These biomolecules are long strands on which there are four types of "beads", nitrogenous bases – adenine, guanine, cytosine and thymine. In the double helix opposite adenine can be only thymine, and opposite guanine – only cytosine.
Knowing the location of the bases in a single-stranded DNA molecule, you can pick up a set of short "staples" for it, which will make the chain compactly fold, for example, into a flat sheet. According to the creator of the technology, Paul Rotmund from Caltech, it takes about two weeks to develop and synthesize these "paper clips", and the process of creating origami takes several hours after mixing the components in solution. Ten years ago, a chemist from the ring DNA molecule of the bacteriophage M13 created several simple geometric shapes – triangles, stars, rectangles and emoticons.
The principle of DNA origami assembly and photonic crystal creation (upper and middle row). Bottom row: a method of attaching origami to a photonic crystal (due to carboxyl groups) and origami micrographs on the crystal surface. In the lower right corner is the reflection spectrum of the area to which the phosphor molecule is attached.
In the new work, Rotmund and his colleagues used the DNA origami technique to directionally attach phosphor molecules to the surface of a two-dimensional photonic crystal. The crystal was an ordered structure resembling a honeycomb. To make it, scientists used the method of etching the surface using an electron beam. According to the authors, origami with dye had to be located in special areas in which the structure of the honeycomb was broken – there were no three adjacent recesses. In order for the molecules to bind effectively to the regions, scientists activated up to seven sites on them during the manufacturing process. Depending on the location of the attached phosphors, the intensity of the glow of individual parts of the crystal changed.
The dependence of the phosphor glow on the position of origami inside the "landing pad"
To demonstrate the technology, the authors decided to reproduce the painting "Starry Night" by Vincent van Gogh in a monochrome version. According to Ashwin Gopinath, the co-author of the work, he was inspired by one of the Doctor Who series ("Vincent and the Doctor"), in addition, he always liked this picture. As a basis for the reconstruction, scientists chose a picture of the painting published in Wikipedia. In total, the authors needed to create 65,536 "landing pads" for triangular origami molecules with phosphors.
The location of origami adapters in the cavities.
Test experiments on color transfer and "Starry Night"
The dependence of the luminescence of phosphors on the place of their attachment is an important effect that allows us to study the internal band structure of a photonic crystal, and, in particular, to clearly show the local density of states in it. The authors note that thanks to this technique, it will be possible to investigate an unusual phenomenon – superradiance. This is a process whereby a large number of light-emitting objects (phosphors or excited atoms) can synchronize the emission of photons. Scientists compare it with the spontaneous synchronization of several metronomes standing side by side. Although superradiance was theoretically described 55 years ago, there are few experimental tests of it.
The DNA origami technique finds application in various fields, ranging from materials science to medicine. So, with the help of this technique, it was possible to overcome the drug resistance of blood cancer. DNA origami was used to create a manipulator that brings together and removes molecules at a given distance with an accuracy of 0.4 angstroms, as well as special containers and scissors. The technology also allows you to create three-dimensional objects, for example, chemists from the University of Arizona put together a snub-nosed cube from DNA.
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13.07.2016