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Carbon nanotubes will enable rapid gene sequencing

For DNA floor Mahira has enormous potential in the fields of biology and medicine, especially for personal diagnosis and personalized treatment based on the composition of the individual genome of each and every one of us.

A carbon nanotube in the shape of a ring fence, with DNA sequences painted in different colors inside
A carbon nanotube in the shape of a ring fence, with DNA sequences painted in different colors inside

For DNA floor Mahira has enormous potential in the fields of biology and medicine, especially for personal diagnosis and personalized treatment based on the composition of the individual genome of each and every one of us. Today, however, the floor method is still cumbersome and expensive for most clinical applications, although this situation may change thanks to a variety of innovative and inventive methods.

In the current issue of the journal Science, Stuart Lindsay, director of the Center for Biophysics at Arizona State University, together with his colleagues, demonstrated the potential of one of the methods for gene sequencing in which a single helix of DNA. is threaded through a carbon nanotube and thereby produces electrical signals that provide information about the bases of the sequence - a process known as translocation.

Carbon nanotubes are cylindrical, multipurpose structures used in nanotechnology, electronics, optics and other areas of materials science. They consist of allotropes of carbon - different arrangements of carbon atoms, and exhibit unique properties of strength and electrical conductivity.

Normal methods for reading the genetic code, which consists of four nucleotide bases (adenine, thymine, cytosine and guanine: A, T, C, and G), are based on deriving the DNA fragment. For hundreds of thousands of pieces, reading these truncated segments and finally, reconstructing the complete genetic sequence using serious computing power. About a decade ago, the first complete human genome - a sequence of about three billion chemical base pairs - was successfully deciphered after a supreme effort. The mission lasted about eleven years and cost about a billion dollars. Beyond the complexity of the existing methods, the accuracy of the floor is impaired due to cumulative errors as a result of the large number of segments that must be read.

A new approach uses nanopores - nozzles of molecular diameter that connect two fluid reservoirs. A constant electric flux can be activated between two electrodes located at each of the ends of the nanopore while receiving an ionic current passing through a closed channel inside the nanopore. At this molecular scale, the passage of materials, even of one particle, generates a measurable change in the flow of electric current within the pore. This current change is then amplified and measurable. Only very recently have advanced microfabrication methods allowed researchers to construct nanopores at the scale of single cells, paving the way for a multitude of possibilities for the examination and study of individual cells.

In the current study, single-walled carbon nanotubes, which are about one to two nanometers in diameter, were used to create the electrically conductive channels. When an electrical voltage was applied to the channel, segments of DNA Single-helixes (also known as oligomers) consisting of sixty or one hundred and twenty nucleotides were drawn to its opening and moved from its anodic side to its cathodic side, and this is due to the negative electrical charge present on the DNA strand. DNA movement speed Depends on both the nucleotide structure and the molecular weight of the DNA sample.

The carbon nanotubes deliberately "grew" out of an oxidized zinc layer. The findings showed that for the nanotubes that were successfully created - those that are open at both ends and have no leakage throughout - a sharp change in their electrical activity was measured during the movement of the DNA. In addition, changing the polarity of the electrodes caused the voltage changes to disappear; Restoring the original polarization caused the voltage changes to return.

The researcher emphasizes that the measured temporary electrical signals, each of which contains about ten million charged particles, represents a huge amplification of the charge moving in the pore channel. A well-known method of quantitative PCR was used to verify that the carbon nanotubes responsible for the voltage changes - about twenty percent of the sample's content - are indeed the ones within which the DNA movement took place.

The team conducted molecular simulations to determine the mechanism responsible for receiving these large ionic currents in the nanotubes. Examining the voltage-current curves obtained at varying conductivity levels showed that the movement of a charged coil inside the tubes is very unusual, and further studies will be required to understand its exact mechanism. Nevertheless, the electrical signal characteristic of DNA movement. within tubes with high ionic conductivity could provide further progress in the effort to apply nanoporous technologies for DNA flooring. fast

The success of the rapid floor using nanopores depends on precise control of DNA movement. The hope is that the reading of the genome can be greatly accelerated, and still provide enough time for the DNA bases. will be detected by electrical signals. Carbon nanotubes provide a possible alternative in making the control of nanopore properties easier and more reliable.

If the process can be perfected, emphasizes the chief researcher, DNA sequencing will be possible. Which will be thousands of times faster than the speed available with current methods, at a negligible cost. The method could significantly advance the goal of personalized medicine based on "single-patient-single-genome" and assist in the provision of essential diagnostic information, as well as assist in the pioneering development of personalized treatments against a wide variety of diseases.

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3 תגובות

  1. I would also be happy, Ami Bachar, if you wrote what you wrote in more "popular" Hebrew.
    And second thing:
    When they say "personalized medicine based on "single-patient-single-genome", they are basically telling you to give your DNA for testing in order to match you with drugs.
    But it is clear, the information that will be collected about you from the DNA test will reach anyone who wants to know!
    This means that your "tendency" (chance) (and that of your children in the future) to get certain diseases, your expected life span, intelligence and all the other things that you might prefer that no one knows (maybe even you won't know) except of course your attending physician, will be determined You know where you can be accepted and how much they will invest in you (from daycare to university, from friendship to wedding and starting a family).
    Don't get me wrong, I'm in favor of risking exposure, because the end sometimes justifies the means.
    And the goal is an easier and longer life.
    And even if (that we don't know) someone has DNA that is "not something", maybe if he lives enough years, he will be able to reach a time when medicine will know how to "fix" the DNA or change the DNA sequence to a better sequence.

  2. In the meantime we are satisfied with raising 400 clones for $500 or pyrosequencing for $12
    Looking forward to the day…

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