Related topics: dna sequences

Water compresses under a high gradient electric field

Modern civilization relies on water's incompressibility—it's something we take for granted. Hydraulic systems harness the virtual non-compressibility of fluids like water or oil to multiply mechanical force. Bulldozers, ...

A billion holes can make a battery

Researchers at the University of Maryland have invented a single tiny structure that includes all the components of a battery that they say could bring about the ultimate miniaturization of energy storage components.

Portable, rapid DNA test can detect Ebola and other pathogens

Using technical advances not yet developed when the 2014 Ebola outbreak began, UC San Francisco-led scientists completed a proof-of-principle study on a real-time blood test based on DNA sequencing that can be used to rapidly ...

NASA's DNA sequencing in space is a success, researchers confirm

Two hundred miles above Earth, NASA has conducted the first genome sequencing in space, and researchers at UC San Francisco helped analyze the data sent back from the International Space Station and confirm that the process ...

Graphene may hold key to speeding up DNA sequencing

September 9, 2010 - In a paper published as the cover story of the September 9, 2010 Nature, researchers from Harvard University and MIT have demonstrated that graphene, a surprisingly robust planar sheet of carbon just one-atom ...

Mini DNA sequencer tests true

The MinION, a handheld DNA-sequencing device developed by Oxford Nanopore, has been tested and evaluated by an independent, international consortium coordinated by EMBL's European Bioinformatics Institute (EMBL-EBI). The ...

Tiny reader makes fast, cheap DNA sequencing feasible

Researchers have devised a nanoscale sensor to electronically read the sequence of a single DNA molecule, a technique that is fast and inexpensive and could make DNA sequencing widely available.

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Nanopore

A nanopore is a small hole in an electrically insulating membrane, that can be used as a single-molecule detector. It may be considered a Coulter counter for much smaller particles. It can be a biological protein channel in a high electrical resistance lipid bilayer, a pore in a solid-state membrane or a protein channel set in a synthetic membrane. The detection principle is based on monitoring the ionic current passing through the nanopore as a voltage is applied across the membrane. When the nanopore is of molecular dimensions, passage of molecules (e.g., DNA) cause interruptions of the "open" current level, leading to a "translocation event" signal. The passage of RNA or single-stranded DNA molecules through the membrane-embedded alpha-hemolysin channel (1.5 nm diameter), for example, causes a ~90% blockage of the current (measured at 1 M KCl solution).

Solid-state nanopores are generally made in silicon compound membranes, one of the most common being silicon nitride. Solid-state nanopores can be manufactured with several techniques including ion-beam sculpting and electron beams.

Nanopores may also be used to identify analytes other than DNA. Professor Hagan Bayley’s Research team at the University of Oxford has published research that uses protein nanopores to differentiate between enantiomers of small molecules such as ibuprofen and thalidomide, identify specific biomarkers and screen ion channels. These might have broader applications in clinical medicine and drug development.

The observation that a passing strand of RNA containing different bases results in different blocking levels has led to the nanopore sequencing hypothesis. Oxford Nanopore Technologies and Professor Hagan Bayley's laboratories have shown identification of individual nucleotides including methylated cytosine as they pass through a modified hemolysin nanopore.

Such sequencing, if successful, could revolutionize the field of genomics, as sequencing would be simplified and have the potential for dramatic improvements in power and cost over current versions that use fluorescence/luminescence and optical instrumentation to detect this photon signal. Apart from rapid DNA sequencing, other applications include separation of single stranded and double stranded DNA in solution, and the determination of length of polymers. At this stage, nanopores are making contributions to the understanding of polymer biophysics, as well as to single-molecule analysis of DNA-protein interactions.

Size-tunable elastomeric nanopores have been fabricated, allowing accurate measurement of nanoparticles as they occlude the flow of ionic current.This measurement methodology can be used to measure a wide range of particle types. In contrast to the limitations of solid-state pores, they allow for the optimisation of the resistance pulse magnitude relative to the background current by matching the pore-size closely to the particle-size. As detection occurs on a particle by particle basis, the true average and polydispersity distribution can be determined. Using this principle, the world's only commercial tunable nanopore-based particle detection system has been developed by Izon Science Ltd.

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