Nanopore

A nanopore is a small pore in an electrically insulating membrane, that can be used as a single-molecule detector. A nanopore is a Coulter counter for much smaller particles. It can be a biological protein channel in a lipid bilayer or a pore in a solid-state membrane. The detection principle is based on monitoring the ionic current of an electrolyte solution 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" pulse. The passage of 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). The observation that a passing strand of DNA containing different bases results in different blocking levels has led to the nanopore sequencing hypothesis. Such sequencing, if successful, could revolutionize the field of genomics, as sequencing could be carried out in a matter of seconds. 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.

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Solid-state nanopores are generally made in silicon compound membranes, one of the most common being Si₃N₄. Solid-state nanopores can be manufactured with several techniques including ion-beam sculpting[1] and electron beams[2].

See also

• Nanopore sequencing

External links and references

• Links to nanopore research groups
• The Harvard Nanopore Group
• NanoSEQ - The Global Exchange for Nanopore Research
• UC Santa Cruz Nanopore Project
• DNA heterogeneity and phosphorylation unveiled by single-molecule electrophoresis
• Computer simulations of nanopore devices