Cheaper, more accurate DNA sequencing
Dutch Research Council grant image: Amedeo Bellunato
A new graphene-based method could make for faster, cheaper and more accurate DNA sequencing, say a group of Leiden physicists and chemists. They have received EUR 1.2 million through the Dutch Research Council (NWO) Open Technology programme to prove their new method.
The new DNA sequencing method builds on a previous Leiden discovery in which the research groups of chemist Grégory Schneider and physicist Jan van Ruitenbeek got an electrical current to jump across two layers of graphene, each an atom thick. By bringing the two layers close together at a certain angle, they caused tunnelling to occur. This is a quantum mechanical phenomenon where electrons jump from one material to another despite there being no direct contact between the two.
How does it work?
If you separate the two layers slightly, the tunnelling ceases. ‘Unless a small object, such as a molecule, passes between the two layers’, Schneider explains. ‘Then the tunnelling is activated and characteristics of the molecule can be sequenced.’
How does it work? This DNA sequencing method – determining the sequence of nucleotides in DNA – is sensitive to the electronic characteristics of nucleotides. ‘DNA consists of four nucleotides, which are shortened to the acronym ACGT’, says Ruitenbeek. ‘If a DNA string passes between the graphene, we think this method will enable us to identify each separate nucleotide by the strength of the current at the moment when that specific nucleotide passes.’ This will allow for DNA sequencing.
Demonstrating the method works
If the new method works, it will be more accurate than other DNA sequencing methods. A common DNA sequencing method uses nanopores and is only sensitive to differences in size between the building blocks of the molecule. If two building blocks that are of an equal size but a different chemical composition pass simultaneously through a measuring point, they emit the same signal. ‘We expect to be able to measure different signals with our tunnelling method’, says Schneider.
The physicists and chemists have good ideas on how to pass the molecule between the graphene but they still have to demonstrate that it really does work. They also want to prove they can differentiate between the four nucleotides in their analyses. The funding will enable them to do so.
From diseases to endangered animals
The group expects this method to be more accurate than other methods, which will enable a wider group of researchers and other professionals to use it for DNA sequencing and detecting individual molecules in general: for research on different diseases, for example. But there is also interest from customs at airports. They could use this method to quickly find out whether someone is carrying endangered animals or plants. The method could also be used to detect certain molecules in, for example, containers used to transport food. Then you could quickly test for the presence of gas that causes the food to rapidly decay. ‘You could use it wherever you need to detect a certain molecule at a very low concentration, down to a single molecule’, says Schneider.