Quantum Tunneling DNA Sequencer
Quantum tunneling has been adapted to read the DNA sequenceScientists were able to adapt quantum tunneling to read the sequence of nucleotides in DNA.
In the future, a new method for identifying nucleotides may be the basis for a new method of DNA sequencing – simple, reliable, fast and, most importantly, practically does not require complex consumable reagents, and therefore cheap.
The staff of the University of the American State of Arizona, led by Stuart Linsey, showed that the shape of the current curve recorded by a scanning tunneling microscope depends on which nucleotide is on a conductive substrate if a scanning molecule is attached to the metal needle of the microscope. By the differences in shape, it is quite possible to determine which nucleotide is on the substrate.
As the authors of the article accepted for publication in Nature Nanotechnology (Shuai Chang et al., Tunneling readout of hydrogen-bonding based recognition) show, the differences are determined by the nature of the hydrogen bonds formed between the scanning molecule and the read nucleotide. Adenine and thymine hold two hydrogen bonds between them, and cytosine and guanine hold three pairs of atoms, which makes the bond stronger. These differences are reflected in the rate of decrease of the electron current, which, in accordance with the laws of quantum mechanics, can pass from the needle to the substrate, even if this requires overcoming a potential barrier greater than the voltage applied between the conductors. In the case of a cytosine-guanine pair, the current decreases more slowly while the additional bond is destroyed.
Scientists hope that their technique can result in the creation of a new method of DNA sequencing, which will not need expensive reagents to cut DNA into fragments and copy them repeatedly before reading. Now these reagents cost several tens of thousands of dollars per (human) genome, although there are plans to reduce this amount by orders of magnitude.
However, while the new technique is unlikely to be able to compete both in price and speed. Reading one human genome using this technique with a single tunneling microscope will take several months, and the tunneling microscope itself is not a cheap thing; there are many other technical difficulties. However, the technical problems facing the first chemical sequencers were even more complicated. But these difficulties were solved in just a few years.
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