DNA sequencing: molybdenum disulfide instead of graphene
New material could make DNA sequencing faster and more accurate
NanoNewsNet based on materials from the University of Illinois at Urbana-Champaign:
New material could enhance fast and accurate DNA sequencingGene-based personalized medicine opens up broad prospects in diagnostics and targeted therapy, but the development of this area is hindered by one "bottleneck":
the expensive and time-consuming process of DNA sequencing. However, scientists have recently found that molybdenum disulfide can make DNA sequencing more accurate, faster and cheaper than any other material available today.
Personalized medicine based on genomics opens up broad prospects in diagnostics and targeted therapy, but one bottleneck hinders the development of this field: the expensive and time-consuming process of DNA sequencing.
However, scientists at the University of Illinois at Urbana-Champaign recently found that molybdenum disulfide (MoS 2) can make DNA sequencing more accurate, faster and cheaper than any other material available today.
"One of the most important areas of science is the sequencing of the human genome at a price below $1,000, the "genome at home"," says the head of the study, Professor of mechanics and Engineering Narayana Aluru. "Now there is a real hunt for good material. We used MoS 2 to solve other problems and thought why don't we see if it would be suitable for DNA sequencing."
Apparently, MoS 2 is superior to all other materials used for nanopore sequencing, including graphene.
A nanopore is a tiny hole drilled into a thin sheet of material. This pore is large enough for a DNA molecule to pass through it. DNA is pushed through the nanopore by an electric current, and current fluctuations during the passage of a biomolecule through it make it possible to determine its nucleotide sequence, since each of the four letters of the DNA alphabet – A, C, G and T – is slightly different in shape and size.
The DNA molecule passes through a nanopore in a layer of molybdenum disulfide, a material that, according to scientists,,
it will make DNA sequencing more accurate, faster and cheaper.
(Photo: Amir Barati Farimani)
Most of the materials used for DNA sequencing using nanopores have a significant drawback: they are too thick. The thickness of even a very thin plate of most materials is larger than several links of the DNA chain, which makes it impossible to accurately determine its nucleotide sequence.
One of the most commonly used materials for DNA sequencing is graphene, since it is a monatomic carbon layer, which means that only one base passes through the pore at a time. Unfortunately, graphene also has a number of problems, and the most significant of them is the adhesion of a biopolymer molecule to it. The interaction of DNA with graphene induces a large amount of noise, which makes it very difficult to read the current.
MoS 2 is also a monatomic layer, thin enough for only one DNA letter to pass through the nanopore at a time. Professor Aluru and his colleagues found that DNA does not stick to MoS 2 and passes through the pore neatly and quickly.
"MoS 2 is a competitor of graphene in the field of transistors, but by showing that it is capable of being a bio–sensor, we have demonstrated new technical capabilities of this material," comments graduate student Amir Barati Farimani, first author of the article DNA Base Detection Using a Single-Layer MoS 2 (ACS Nano, 2014).
Computer simulation of sequencing based on MoS 2 gave four different signals corresponding to the bases of a double-stranded DNA molecule. Other systems give at best two – A/T and C/G – which then require complex computational analysis to distinguish A from T and C from G.
Now researchers are studying whether it is possible to achieve even greater productivity by combining MoS 2 with some other material.
"The ultimate goal of this study is to create a home, or personal, device for DNA sequencing," comments Barati Farimani. "By finding technologies that allow us to quickly, cheaply and accurately identify the human genome, we are getting closer to this goal. A map of our DNA can help prevent or detect diseases at the earliest stages of development. If we get the opportunity to sequence our DNA cheaply, we will know our genetic map and will be much more attentive to what is happening in our body."
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