DNA scanning using graphene nano-nozzles

A team of researchers from the University of Delft in the Netherlands presented a new type of nanoporous devices that could have a significant impact on the way we scan DNA and decipher the sequences within it. With the innovative method, the researchers were able to create tiny nozzles using a layer of graphene and use them to detect the movement of DNA fragments. A particles passing through the nozzles.

Today, throughout the scientific world, there is a race to develop fast and economical methods for DNA sequencing, that is, to read the content of our genome (the genetic code) and decipher it.

One type of device that is particularly promising for the next generation of sequencing methods is the device where the measurements are made using a single fragment. Imagine a single DNA fragment from one of your cells (three billion bases, one meter long if we stretch the coil) undergoing a read - Base by base - in real time as it moves between two of your fingers. This is the idea of ​​the team of researchers, led by Professor Cees Dekker. Now, the researchers are demonstrating the first step in this idea: moving a single fragment of DNA through a tiny nanometer hole found in the thinnest membrane that nature can offer - the material graphene, which consists of a single-atom-thick layer.

Graphene is a unique and unusual material, and yet, extremely common: everyone has graphene in their home - the material graphite consists of layers of graphene and is found, for example, in pencil tips, coals or soot from candles. However, in this study, graphene material was used due to its special feature - the possibility of preparing monolayers of graphene with a thickness of a single atom. Why would such a thin membrane be important? The space between two DNA bases is extremely small, about half a nanometer. In order to "read" each of these bases, it is necessary to use a recording medium smaller than half a nanometer in size.

The research team prepared a nanometer-sized hole - a nanohole - in the graphene membrane, a system that is the ideal recording medium. They showed that individual fragments of DNA in water can be captured by these graphene nanopores, and more importantly, can be decoded as they pass through the pore. The detection method is extremely simple: following the application of a current along the nanohole, ions (electrically charged particles) found in the solution begin to move through the hole and the resulting current can be measured. This current decreases when a DNA fragment passes through the nanopore following a partial blockage of the movement of ions in the solution. So that each individual DNA fragment passing through the pore can be detected by a decrease in current.

The DNA fragment passes through the hole base by base. Using the monoatomic graphene nanohole it is possible, in principle, to read the DNA sequence, base by base. Several research groups around the world have been trying for some time to realize the potential of graphene nano-nozzles. This research group is the first to publish findings in this field.

Moving DNA using nano-nozzles was previously developed in the same laboratory, as well as by other research groups in the world, using silicon-nitrogen (SiN) membranes. Graphene nanonozzles offer new opportunities - far beyond DNA sequencing. Since graphene, unlike the SiN material, is an excellent electrical conductor, the next expected step will be to use its inherent conductive properties. Nanonozzles allow a variety of opportunities for the development of sensors in the fields of science and medicine.

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